MODERN CONSTRUCTION HANDBOOK ANDREWWATIS SECOND EDITIO N
~ SpringerWienNewYork
3 INTRODUCTI ON 4 MATERIALS Introduction to Second Edition 4
6
Taxonomy of material systems 8
Changes from the First Edition
4
Structure and envelope
10
Structure of this book
5
Digital tectonics
12
Parametric design
16
WALLS
82 ROOFS
Trends in facade design
84
Generic wall types
90
Trends in roof design
200 202
Metal roofs Metal
( I) Metal standing seam
206
( I) Sheet metal
92
(2) Profiled metal sheet
2 10
96
(3) Composite panels
214
Tectonics in metal
20
(2) Profiled cladding
Steel
22
(3) Composite panels
100
(4) Rainscreens
218
Aluminium
26
(4) Rainscreens
104
(5) Metal louvres
222
Copper, zinc and lead
30
(5) Mesh screens
108
(6) Louvre screens
11 2
Tectonics in glass
32
Glass
34
Glass roofs ( I) Greenhouse glazing
Glass systems
11 6
and capped systems
( I) Stick systems
120
(2) Silicone-sealed glazing
226
Tectonics in concrete
38
(2) Unitised glazing
124
and roofiights
230
Concrete
40
(3) Clamped glazing
128
(3) Bolt fixed glazing
234
(4) Bolt fixed glazing
132
(4) Bonded glass roofiights 238
Tectonics in masonry
46
(5) Glass blocks and channels 136
Masonry
48
(6) Steel windows
140
Concrete
Concrete block
50
(7) Aluminium windows
144
( I) Concealed membranes 242
(8)Timber windows
148
(2) Exposed membranes
246
(3) Planted roof
250
Stone
52
Brick
54 Concrete
Tectonics in plastics
56
( I) Cast in situ
152
Timber roofs
Plastics and composites
58
(2) Storey height precast
156
( I) Flat roof: mastic asphalt
(3) Small precast panels
160
coverings
Tectonics in timber
62
Timber
64
Fabrics and membranes
68
254
(2) Flat roof: bitumen-based Masonry loadbearing walls
164
sheet membranes
258
(3) Pitched roof: tiles
262
Masonry cavity walls Internal walls
( I) Brick
168
Plastic roofs
(2) Stone and block
In
( I) GRP roofiights
(2) GRP panels and shells 270
( I) Fixed and demountable
ri
(2) Plaster systems
74
Masonry cladding
176
(3) Wallboard systems
76
Masonry rainscreens
180
266
Fabric systems ( I) ETFE cushions
Floors
78
Plastic
Ceilings
80
( I) Plastic-based cladding
184
(2) Single membrane:
(2) Plastic rainscreens
188
cone-shaped roof
274 278
(3) Single membrane: barrel-shaped roof
Timber ( I) Timber frame
192
(2) Cladding panels
196
282
CONTENTS
5 STRUCTURE
286 ENVIRONMENT 354 FUTURE Energy and the building
Material systems for structures
6
288
I
418 REFERENCES
A future for building
Glossary of term s
496
500 501 502
envelope
356
construction
420
Authorship
Double skin facades
358
( I) Folded glazing
422
Index
362
(2) Metal solar shading: louvres
Photo credits ( I) Braced frames Reinforced concrete
292
Environmental studies for
Steel
296
envelopes
Timber
300
and mesh
428
Analysis for design (2) Portal frames
304
(3) Loadbearing boxes
( I) Solar radiation
364
(3)Triangular panels for twisted
(2) Daylight
368
facades
(3) Embodied energy
372 (4)Twisted panels with fiat glass
Reinforced concrete
308
Brick
3 12
Passive design
Glass
316
( I) Natural ventilation
(4)Trusses
320
daylight controls
378
(3) Solar power
380
(6) Precast concrete panels
(4) Solar heating
382
for facades of complex
324
for twisted facades
440
(5) Moving shading panels
448
376
(2) Solar shading and
(5) Arches and shells
geometry (6) Space grids
328
434
452
Low energymaterial systems ( I) Straw bales and hemp
Floor structures
(2) Rammed earth, cob
( I) Cast in situ /
and adobe bricks
384
(7) Glazing systems wit h integral solar shading
458
386
cast-in-place concrete
332
(3) Green oak
(8) Stick glazingfor double
(2) Precast concrete
334
and bamboo
388
(3) Steel and steel mesh
336
(4) Green walls
390
(4) Timber
338
(5) Glass
342
facades
464
(9) Shingled glazingfor facades Active design
of complex geometry
470
( I) Liquid based heating/ Stairs
cooling systems
392
( I0)Variable concrete panels for solar shading
(2) Mechanical heating/
(2) Steel
346 348
cooling systems
394
(3) Timber
350
(3) Electrical lighting
400
( I I) Str uctural facades of
(4) Glass
352
(4) Fuel and water supply
402
complex geometry
( I) Concrete
( I) Sanitation and drainage
404
(2) Fire control
406
(3) Maintenance and (4) Lifts
482
( 12) Facade with integrated
Support services
cleaning
476
408 414
furn iture
488
494
lntroduction to Second Edition
that event ually formed the basis of this book
ferent approach to construction.This book
began /5 years agowhen I was an archit ect
A view expressed in this book is that there
suggests how buildings can be designed and
working at Jean Nouvel's office in Paris,
are no fixed methods of construction;tech-
constructed wit h a limited number of mate-
developing projects for construction,typically
niques are constantly evolving, both by multi-
rial systems, much t he way buildings were
designing from the basis of small models
plying the number of components in a given
assembled before the imperatives of mass
The Modern Construction Handbook
and sketch proposals.The early design wor k
assembly in order t o perform better as well
production with its attendant need for repe-
done by others in the office was always
as searching for new ways of re-integrating
tition of ident ical components.This approach
highly aspirational, often without an estab-
and simplifying these systems.
is based on a closer tecto nic relationship between walls, roofs and structure rather
lished method of construction available to realise the designs.The aim of moving designs forward towards their construction was to bring as much of the design int ention
How does this edition vary from the First Edition? The First Edit ion of the Modern Con-
than the contemporary approach of juxtaposing systems that are manufactured quite independently of one another.More than
as possible into the finished building.This was
struction Handbook concerned itself prima-
a question of individual design choice, con-
achieved by matchingthe essential design
rily wit h setting out forms of construction
struction is an essential aspect of our culture,
ideas to forms of construction which could
in typesgrouped by their primary material.
both as a process involving a large number
be developed by the designteam to achieve
Wh ile textboo ks on construction divided
of individuals who traditionally have shown
tho se aims; ideas which were spatial,techni-
building elements int o components and
craftsmanship in their work,whether on
cal and social.The built results varied in their
assemblies rather than 'systems' based on the
sit e or in a workshop, and as an expression
technical ambition, but were always root ed
possibilities of the material used,the Modern
of the values cherished by our society.The
in these early design aspirations, built either
Construction Handbook aimed to set out
idea of individual craftsmanship is a primar y
as a 'diagram' or 'fragment' of an idealised
construction systems with a balanced and
architectural motivation which is explored in
design that was embodied both in the early
even t reatment of the different methods of
this book,with examples of where this might
design models and in conversations wit hin
constructing structures, walls and roofs and
lead in emerging archit ecture that is cur-
the office.An alt ernative approach taken
internal construction, with no system given
rent ly being developed tod ay.
on some projects wast o take one or two
more priority or described with more infor-
The simp/est evolutions in material
aspects of the primary design aspirations and
mation than any other.Essays on prefabrica-
systems can lead to quite unexpected sys-
develop only t hose to a much greater extent
tion, possible future directions for construc-
tem 'behaviour' which does not necessarily
than other components of the 'tectonic',
t ion, and their relationship to environmental
follow expected rectilinear building forms.
or parts of the construction which were
design set the agenda for Modern Construc-
The greater geometric fiexibility of t hese
considered to combine spatial,t echnical and
tion Facades and Modern Construction
'evolved' versions of contemporary material
social issues.This design process is common
Roofs, books which followed in the series.
systems allows buildings to engage more
to archit ecture that engages fully with the
This Second Edition sets out these
flexibly with our existing built environment.
possibilities of building construction:the
element s of construction in a way which
W here modernist architecture t o date has
process of building as an expression of the
explains the main principles of each con-
admired simple geomet ric forms and their
process of bringing design aspiration to life,
struction system and point s to an expres-
relatively simple interplay, material systems
rather than buildings asself-contained 'jewels'
sion of architecture based on exploring the
can be used to interact with the existing
or as visually coherent expressions of ideas
possibilities of material systems beyond the
fabric and to work wit hin it rather than
with a modest architectural basis.
cladding of structural frames. Cladding can
encourage a complete replacement of entire
Exploring forms of construction wit h
be considered as beinga 'collage' or juxta-
parts of t he built environment.This approach
other archit ects in the office led me to build
position of independent material systems,
is one which was enjoyed before the mass
up a set of sket ches of 'mat erial systems',
all manufactured in isolation of one another,
industrialisation of building production in the
since none were readily available in books,
each system seeing it self as addressing a dif-
early 20th century. In many waysthis book
MCH
4
demonstrates that the pre-industrial world
from the Walls chapter are available in an
and 'services' rather than being regarded as
of significant buildings,that formed a part of
accompanying book in the Modern Con-
fittings. Consequently, the Fittings chapter
our urban environment, can find a continu-
struction Series,called Modern Construction
from the First Edition is omitted, with materi-
ation in the world of digital fabrication and
Facades, which includes more information on
al re-allocated to the other chapters. In place
mass customisation.
detail conditions within each material system.
of Fittings is Future, showing how some of
Another accompanying book called Scratch-
the material systems could be developed in
ing the Surface, also published by Springer
new buildings.These 'future' material systems
Wien New York, sets out progressive exam-
are based on research work undertaken at
'components' identified as structure, walls,
ples of material systems in buildings of a size
our practice, Newtecnic, for consideration on
roofs and environment, following the way
and type experienced by most architects in
live projects.
contemporary buildings are designed by
general practice of modest budget and mod-
specialist consultants and constructed by
est scale.
Structure of this book This Second Edition is based on building
Qualifying commemts
specialist contractors. While the First Edition
The Roofs chapter is re-structured and
The building techniques discussed and
focussed on only material systems produced
developed to follow Modern Construction
the built examples shown are designed to
by mass production techniques, the future
Roofs, another book in the series, basing the
last for an extended period with a relatively
chapter of the Second Edition adds in sys-
classifications more firmly on systems than
high performance. Consequently; buildings
tems that could be produced by mass cus-
on types of roof covering as set out in the
for exhibitions and for temporary use are
tomisation techniques. Considerably more
First Edition of the Modern Construction
excluded. In addressing an international
information is added than that of the First
Handbook. This provides a closer link with
readership, references to national legislation,
Edition, with the addition of more materi-
the Walls chapter.
building regulations, codes of practice and
als and more systems. Within each chapter,
The Structures chapter, like the Walls and
national standards have specifically not been
material systems are grouped in terms of
Roofs chapters, has a complete set of new
included. This book explains the principles
the primary material used to construct the
drawings that explains the systems more
of accepted building techniques currently in
system, following the same order of materi-
clearly The relationship of the other building
use. Building codes throughout the world
als listed in terms of their density; from heavy
components to structure informs much of
are undergoing increased harmonisation
to light, used in the first chapter on materials.
architectural design, so this has been the basis
because of increased economic and intel-
Within each material classification, systems
of new essays in the Materials chapter.
lectual globalisation. Building components and
progress from more traditional technology
'Services' are designed increasingly to
to more recent, largely following their his-
use both 'passive'and 'active' systems and are
often used in a single building. Since build-
torical development.
referred to under the more general term of
ing codes are written to protect users of
'environment', which forms its own chapter.
buildings by providing for their health and
physical properties of each of the main
This Second Edition has been strengthened
safety; good construction practice will always
building materials explored in the book.
with the addition of information on low
uphold these codes as well as assisttheir
The first chapter sets out the essential
assemblies from many different countries are
Materials are set out in order of their density;
energy construction systems from which
advancement. The components, assemblies
from heavy to light, ranging from metals to
complete building envelopes can be manu-
and details shown in this book describe many
glass, concrete, masonry; plastics and timber.
factured.
of the building techniques used by the build-
The second chapter on Walls expands
Remaining items in the First Edition such
ing industry today; but this book does not
information of the systems set out in the
as stairs, lifts, partitions, ceilings and doors
necessarily endorse or justify their use since
First Edition from two pages per topic to
were put into a final chapter called Fittings,
techniques in building are in a continual state
four pages, in common with most of the
which was not an entirely satisfactory solu-
of change and development.
topics covered in the book. More technical
tion.The interior aspects of buildings such as
information and more detailed drawings
stairs and lifts are essential parts of structure
MCH
5
MATERIALS A taxonomy of material systems Structure and envelope Parametric design Tectonics in metal Steel Stainless steel Aluminium Copper. zinc and lead Tectonics in glass Glass Tectonics in concrete Concrete Tectonics in masonry Masonry Concrete block Stone Brick Tectonics in plastics Plastics and composites Tectonics in timber Timber Fabrics and membranes Internal walls ( I) Fixed and demountable (2) Plaster systems (3) Wallboard systems Floors Ceilings
MCH
7
Materials 0 I A taxonomy of material systems
based on the structural frame;typically
quite different headings.Whi le the system
Modern Construction Handbook,which has
either steel or concrete,with the modest,
is useful in describing a building for use by a
been refined for this Second Edit ion, has
but growing, use of timber frames as a lower
contractor;particularly with regard t o nat ion-
undergone several stages of development,
embodied energy alternative.As examples
al standards, including those for performance
based on the idea of grouping construction
of loadbearing construction are rare,the
testing, specifications do not relat e the parts
The organisation of the mater ial in the
systems by the mat erial used rather than
use of categor ies of'loadbearing'and 'non-
in a way that can be easily used at the design
by their 'function', which is one of the most
loadbearing'was not appropriat e due to t he
stage to understand generic facade assem-
widely usedconstruction-based classifica-
imbalance of the categories. Wh at emerged
blies.The approach t aken in the classification
tion systems.The mat erials-based approach
was that construction systems for the major-
system in the Modern Construction Hand-
specific to this book allows the text t o draw
ity of building construction are independent,
book was to group items in a way known to
parallels between building 'systems'that are
wit h few systems relating t o one another.
building design teams: structure, walls, roofs,
based on the same primary mat erial, since
Much of the skill of contemporary detailing
and services.
the development and use of those systems
is in knowing how to bring those systems
is informed mainly by the physical proper-
together which are fabricated or manufac-
cally, been based on a varying relationship
ties specific to each material and the way
tured in isolation of one another.
between loadbearing structure, walls and
t he material is worked, manufactured or
The linking of building systems so that
The construction of buildings has, histor i-
roofs, and this forms t he basis of classifica-
formed for use as a building material. Known
they might be able to interface more easily
tion in this book.In some buildings, walls,
classification systems create a mix between
has long been an aspiration of manufactur-
roofs and structure are a single entity as in
manufacturer-led names for systems, such as
ers, but the current sit uation is one where
medieval cathedrals, with the exception of
'structural glazing', where the glass is often
few systems co-ordinate easily wit h one
their addit ional timber roofs, used to protect
not structural at all,and 'rainscreen cladding',
another.This suggested that the taxonomy of
the structural ceiling. In framed construction
which covers almost any decorative outer
building systems in the First Edition should
the walls and roofs can be continuous over a singlesupporti ng structure,while in many
layer that has open joints. Rather than basing
be based on a robust set of genuinely dif-
classification on that of existing categories,
ferent generic typesthat would have t o be
cases of 20th century construction,walls,
the approach was to start from scratch and
identified independently of current systems
roofs and structure are quite separat e,and
t est material-based categories against one
of classification, such as those described in
are then subdivided within each category
another. In the First Edition,this evolved into
designers' specificatio ns.The structure of
t o provide a 'collage' form of construction
categories of walls, roofs, structure, environ-
architecture-based specifications identifies
where systems are overlaid in the manner of
ment and fitti ngs.Another category of mate-
components and assemblies in inter-related
a visual collage.
rials preceded this, since an understanding of
sections, where each sub-item in the assem-
Most of the primary building materials
the physical nature of materials is essential in
bly is identified independently, such as'cur-
can be used t o make loadbearing structures,
construction-led architecture.
t ain walling', which itself comprises several
where they serve as both structure and
generic external wall types set out in this
enclosure. Other uses of mat erials for walls
construction is the wide range of construc-
book.Specifications then link items such as
and roofs are non-Ioadbearing cladding.
tion systems which are non-Ioadbearing.
'curtain walling' to their constituent materials
However;sometimeswhere different mat e-
Almost all cont emporary construction is
of glass, seals, paint finishes and so on under
rial systems are formed in the same material
An essential aspect of contemporary
MCH
8
in a building, there is still some structural
zone within the building which is an inhabit-
cific details can be created, which forms the
interdependency. Where quite different
able equivalent of the 'twin wall' or 'double
basis of an understanding of what is needed
material systems are mixed, such as in a con-
skin' facade.This has helped to inform both
to be accommodated in different geometries.
crete frame and enclosure, a different inter-
material systems,not all of which need to be
The chapter on 'future' systems adds a para-
dependency emerges, that of allowing each
sealed,as well as the environment chapter
metric component to some of the examples,
material to be expressed separately.
where passive cooling, heating and ventila-
thus highlighting the range of possibilities that
tion can be used to reduce overall energy
might exist for some of the examples shown.
The inclusion of fittings in the taxonomy
The materials chapter in this Second Edi-
of the First Edition proved difficult, with
consumption, as well as create a stronger link
smaller scale items of stairs, lifts, internal
between the built environment of the city
tion presents essays on how the tectonics
finishes and doors placed within the group.
and the building itself The materials for roads
of material systems was used historically and
The term 'internal fittings' was too restricting,
and public spaces do not form part of the
how digital tools are bringing fiexibility back
as some of these components could be used
scope of this book, of course.
into building construction, something which
externally.This was the least satisfying part of
Each generic system is described first in
was considered to be too expensive until the
the First Edition. In this Second Edition this
terms of the properties of the material, then
arrival of CAD/CAM (computer aided design
issue has been resolved by including stairs
how they are used as a material system, and
/ computer aided manufacturing), mentioned
in the structure chapter, doors in the walls
last how that material system 'behaves', or
as a development bringing change in the First
chapter, and internal finishes in the first sec-
can be made to 'behave', to form a building
Edition.This return to an almost pre-industrial
tion on materials. Lifts are now described in
by examining its detailing. Possible develop-
approach to design allows new buildings to
the environment chapter, since they are usu-
ments of some of these material systems are
develop a much closer empathy with existing
ally considered to be part of the mechanical
set out in the future chapter to show how
buildings, even if the technologies used are
systems, the layout of which is designed by
the principles can be extrapolated for use on
very different.The non-rectilinear nature of
a specialist consultant. As a result of this last
new projects.
some of the material systems allows them
decision it could be seen that the environ-
Generic systems are discussed in terms
to engage more robustly and elegantly with
ment section could include both systems
of how they are assembled, and how they
existing fabric, both pre-industrial and that of
that reduce energy consumption by the
work from a structural and/or enclosure
20th century Modernism in architecture.
use of low energy passive strategies, as well
point of view.These paragraphs on 'system
as high energy active strategies, such as
design' show how the generic example
mechanical ventilation, and lifts can be seen
works. The way the system is applied to dif-
as part of this strategy to make tall buildings
ferent geometries is explained in 'system
usable.
details'.The geometries show how the
In environmental terms, the use of sev-
system can be set out on different mathe-
eral layers of envelope and structure in a
matically-based surfaces, and how the system
single building can create a much richer set
can meet at corners and junctions.Two other
of internal spacesthan those provided by
books in the Modern Construction Series,
the single skin envelope.The outer wall can
titled Modern Construction Facades and
be made of a double skin,or even as a deep
Modern Construction Roofs, show how spe-
MCH
9
Materials 0 I Structure and envelope
Well s Cathedral ,Wells,UK
Natural History Museum, O xford, UK Architect Deane and Woodw ard
In terms of constru ction, Modern ist architec -
of the w idespread use of t he structural
N atural H istory Museum, O xford, U K A rchitect Deane and W oo dward
The use of a str uctural frame clad w it h
t ure can be considered t o be an approac h
frame in much of 20t h cent ur y Modern -
no n-loadbearing walls has led to an aesthetic
th at was not an inevit able development
ist archit ecture , th e separat ion of stru cture
typically con cerned with eithe r forming a
of 19th cent ury archit ecture but rat her a
and ext ern al wall has do minat ed, w here
'co llage' of different compo nents, or as a
respon se t o an industrialisation governe d
th e facade is redu ced t o non -loadbearing
repeated modul e of the same compon ent.
by mass production of building co mpo nents
w alls.T his approach has been a result of the
However, loadbearing constructi on can
such as steel sections for fr ames, br icks,
development of structural forms, o riginally
emb race a design approa ch of struct ural
blocks, meta l coil, timber boards and sec-
destined for large scale buildings,w hich have
and environmental integratio n: t he use of
t ions.The use of repeated , recti linear stru c-
fou nd use in much smaller scale construc -
envelope and str ucture combin ed t o create
tural bays, both in plan and elevation, can
t ions, even being used in individual houses in
space in the facade and cont inuity in gro und-
be seen as a response t o t he way the raw
co ntin enta l Euro pe.T he use of loadbearing
scape or urban context. Both loadbeari ng
products used in building are manufactured,
stru ctures for larger scale buildings resulted
and deep rainscreens are possible solutions
including the straight lines of cut t imber and
in facades with 'punched ' window openings
for th is approach .The recent introduction of
plywood used for concrete formwork.
that gave a 'massive' quality to buildings. In
computer controlled too ls has taken away
contrast, the use of t he separat e structural
the imperat ive of mass prod uctio n, offering
can be considered in te rms of it s response
frame w as able to create a visual lightness
instead possibilit ies of'mass custom isation'
t o mass production te chniques through th e
and t ransparency t hat gave greater freedom
w here many componen ts of different size
use of th e structural fr ame , Building co mpo-
t o designers. H owever,the int egrat ion of
can be produced qu ickly t o a high quality
nent s and assemb lies were used as repeated
skin and str ucture into loadbearing facades
Cons eque nt ly, architectural prod uction is no
ident ical elements in building com positions .
can also allow much greater freedom in t he
longer determined by t he need for repeat ed
Th e use of stee l o r concrete fram es led t o
design of the ext ern al envelope to suit the
rect ilinear units used in Modernist designs.In
buildin g envelopes being enclosed in non-
requirements of th e spaces immedi ately
terms of th e relationship between st ruct ure
loadbearing cladding.The use of repeated ,
behind. In the context of th e ex isting built
and ext ern al envelope, th e introduction of
rectilinear bays can be seen as a response
environm ent, a new building can almost
mass custom isat ion suggests th at systems for
to manufacture, includ ing th e straight lines
'grow' out of the adjacent existing building
both facades and structu res could become
20th century Modernist architecture
of cut t imb er and plywood used fo r co n-
using the same mat erials but with a different
mo re com plex and int erd ependent, w hile
crete formwork. Consequent ly,as a result
material system.
remaining eco nom ic by th e standards of
MCH
10
Colonia Guell,Barcelona, Spain.Architect:Antonio Gaudi
Sagrada-Familia, Barcelona, Spain.Architect:Antonio Gaudi
Sagrada-Familia,Barcelona,Spain.Architect: Antonio Gaudi
contemporary building construction.
be seen as a civic exp ression of the manual
rect ilinear structu ral frame . In the I 950s,Eero
work of many craftsmen and labo urers of the
Saarinen used loadbearing concrete in the
medieval world, w as replaced by an archit ec-
TWA Terminal at John F Kennedy Airport in
t ural expression of t he use of mass produced
New Yo rk, a building w hich int egrat es t he lan-
building components t hat were used as t he
guage of str ucture and enclosure with t hat of
A tradition of the integration of structure and envelope T he integration of structure and envelope can be seen in th e Gothic tradition:
raw mate rial for th e specialist fabrication of
partition s, counter s, desks and furniture.The
facades fo rm ing external spaces create d
entire parts in small w orkshops, rather than
furnitu re is cur ved to make it com fortable
by t he fram ing effect of flying buttresses of
that of w ork being all performed on sit e.
for t he curved human physique, linking the
medieval cat hedrals. Such structures also
Gothic Revival buildings such as the O xford
form of w hat inhabits the building to inform
commun icate a sense of the communa l
Museum are built wit h a mixture of load-
th e constr uctio n of th e building it selfThis
effort required to construct t he building:
bearing and framed co nstruction.
building can be regarded as an integration
The w alls,w hich seem t o int egrat e frame and infill wall into a single constructiona l
In t he early 20th centur y t he archit ect Antonio Gaudi saw that an advantage of
of building, int erior spaces and furnit ure t hat marked the buildings of medieval Oxford.A
ent ity, sweep inw ards at roof level t o cre-
loadbearing construction was th at individual
building designed by Eero Saarinen, t he Mil-
ate stone vaults t hat form a cont inuit y wit h
blocks of stone , bricks or concrete blocks
w aukee A rt Museum, was recently exte nded
the wa lls.Onl y a timber roof is required to
could be corbe lled inwards or outwards from
to a design by Santiago Calatrava in a struc-
protect the sto ne ceiling from the effects
t he vertical plane of t he external w all to cre-
ture that create s a loadbearing, or skelet al,
of the weat her.The t imber ro of is not a
at e a comple x vertical section as w ell as a
stru cture, rem iniscent of earlier buildings by
'concept ual' part of the masonry structure,
complex plan. Gaudi's use of brickwork was
O scar N iemeyer.Calatrava's interest in animal
but rat her a necessary addition t hat ensures
based on his own structural investigat io ns, as
skelet o ns goes one step beyond th e interest
t he constr uction provi des a weathert ight
imple mented at t he Sagrada Familia in Barce-
in the structure of Saarinen.
enclosure. Gothi c Revival buildings of th e
lona. In the years th at follow ed, the buildings
19th cent ur y,such as the O xford Museum
of Oscar Ni emeyer int egrated structure and
in England, com bine medieval methods of
skin in projects of var ying brief, fro m ho using
loadbearing co nstructio n wit h industrially
to churches to public buildings, exp loring the
manufactured iron ribs that form a vault ed
po ssibilities inherent in reinforced concret e
roof structure infilled wit h glazing.What can
rather than follo wing the imperat ives of the MCH
II
Materials 0 I Structure and envelope 2
Aerial view,Oxford, UK
Parametric modelling This need for variat ion in more complex
drawings, and that buildings can be seen as
escope and fitting the 'secondary' research
arrangements of linked spaces is tackled
mere 'built drawings' rather than being con-
spaces into it,the design allows both aspects
more comprehensively in projects by Zaha
ceived as'buildings' in the first place. Gehry
of the design to combine as a more bal-
Hadid, whose work is informed by an inter-
is less interested in loadbearing construction
anced composition.This was achieved by
est in parametric design, where spaces can
than in the built forms that can be generated
designing the spaces from the outside in, cre-
be linked by rhythm, and links achieved
from a few material systems which are liber-
ating an envelope to suit the general enclo-
through the assistance of computer soft-
ated from the constraints of mass produc-
sure of spaces, effectively wrapped around
ware, so that many more iterations can be
tion towards an eventual approach of mass
the telescope.The structure supporting the
investigated and explored than are possible
customisat ion.
telescope is set inside the building, requiring
by hand, by conventional 2D CAD, or even by conventional physical modelling. Parametric modellingprovides an interrelationship
a quite different support for the observation
Modernism and construction Modernism developed from aspects
floor.The space between the outer envelope and the inner telescope structure is inhab-
between parts of the building as well as
of architecture of the early 20th century,
ited by the circulation space serving both
the urban space surrounding it, making the
influenced by mass production techniques
t elescope and study spaces.The telescope
cityscape one of interdependence as, once
from about 1920 onwards. In contrast,the
can be considered to be designed from
again,can be found in medieval Oxford .The
approach taken by architects such as Eric
the inside out, while the study spaces are
involvement of structural engineers such as
Mendelsohn in Germany duringthe 1920s
designed from the outside in.The interstitial
Adams KaraTaylor has led to a more ambi-
considered ways of integrating different
zone between the inner and out er structure
tious engagement with loadbearing struc-
aspects of programmes informed strongly
is inhabited by the staircase which rises
tures.The office of Frank Gehry has taken
by the waythe building was constructed.
through the building. In anot her project,the
the use of parametric modelling as a tool for
The Einsteinturm in Potsdam, Germany, by
staircase itselfcould have been part of the
generat ing building forms that would not be
Eric Mendelsohn integrated the needs of a
overall building structure, but here the stair
possible in a practical sense without compu-
research cent re comprising spaces for study
is supported primarily by both inner and
ter software and its link to computer aided
and discussion, with the complimentary
out er structures on its sides.The building's
manufacturing. Gehry is concerned that
requirement for an astronomical telescope
external envelope is built from brick,cov-
archit ects produce buildings that are gener-
to be accommodated in the building.Rather
ered in render. W hile the building could have
ated by the need to be resolved in 2D as
than express the 'primary' aspect of the tel-
been formed in concrete,the construction
MCH
12
Einstein Tower, Potsdam, Germany. Architect: Erich Mendelsohn
EinsteinTower, Potsdam, Germany. Architect: Erich Mendelsohn
method of corbelling brickwork in and out
built environment.and may also depart geo-
and external facade structures creates an
of vertical plane is ideally suited as a method
metrically from its context, as in the case of
opportunity for a buffer zone between them,
to construct a form of this geometry.
Zaha Hadid's design for an extension to the
which could be used as an inhabited space
Louvre Museum in Paris.The design provides
or for circulation around the building, as was
permits this more complex approach to
continuity of material and context wit hout
mentioned in the previoustext on the Ein-
tectonicsthat was dominated in the 20th
compromising the performance of the build-
steinturm by Eric Mendelsohn.The recently
In our own time, the rise of digital tool s
century by the use of the structural frame.
ing in term s of use, organisation and spaces
completed Mercedes-Benz Museum in Stutt-
created within the building while responding
gart by UN Studio has interstitial zones used
acteristic of the construction of Modernist
to environmental imperatives of reducing
for circulation, while interstitial zones which
architecture has been the separation of
energyconsumption within the building.The
are inhabited can be seen in the Phaeno Sci-
As set out in the previous essay, a char-
structure and external envelope. where
new structure can almost be seen as 'grow-
ence Center inW olfsburg, Germany, by Zaha
the facade is reduced to non-loadbearing
ing'out of the adjacent existing building and
Hadid.
'cladding' as a result of the development of
the adjacent groundscape using the same
structural frames, originally destined for large
material but employinga different material
a loadbearing facade has obvious difficulties.
The integration of skin and structure into
scale buildings. In contrast, the use of digital
system. The material system can be chosen
The conventional 'layered'approach of clad-
tools and mass customisation methods can
or developedto suit the design needs of
ding applied to structural forms in Modernist
be used to create a partial or full integration
the spaces immediately behindthe external
construction has the advantage of superim-
of skin and structure as loadbearing facades.
envelope.
posing wat erproofing,thermal insulation and
This revived loadbearing approach can allow
W it hin building designs. spaces can be
vapour barriers to form a sequential wall
a much greater control of the design of the
created in an outward direction from the
build-up. In loadbearing facades it is more
envelope to suit the requirements of the
internal spaces of the building.W here spaces
difficultto integrate these different func-
spaces immediately behind, rather than using
are required to have a high level of techni-
tions into a single structural wall. However,
the repeated bays of structural frames built
cal performance, or specific light conditions
allowing lines of structure to deviate from
using established methods of mass produc-
that are to be created, this can be achieved
the rectilinear rather than beingusedto suit
tion.ln this loadbearing-based approach.
without immediate referenceto the external
primarily rectilinear facade cladding. allows
the choice of material used may be taken
envelope but rather to the building structure.
structure to interact with non-rectilinear
from the immediate physical context of the
An interstitial zone between internal spaces
spaces within buildings. Current Modernist MCH
13
Materials 0 I Structure and envelope 3
.. '
~
.-
..-
..-
..--
.-
.-
..-
~ II
-
::I Paramet ric mode l of a twisted tower
architecture responds to the needs of mass
of the mass production of identical compo-
ing forms have been seen in both twi sted
production,a set of design imperatives of
nents towards a new period of craftsmanship
and folded geometries.
repeatability and a rectilinearapproach based
as a result of mass customisation.
on mass production rather than the possibili-
A design approach of designing inwards
Twisted building forms achieve geometric complexity by using curves,typically across
ties provided by digital tool s of design and
from the facade of the building, and outwards
a surface of constant curvature in order
production available wit h mass customisation.
from the internal spaces of the building, could
to make it easierto build in a construction
allow structure to create interstitial space
market that is used to mass production tech-
The renewed interest in the structural design of the externalloadbearing wall cre-
between inside and outside.This approach
niques of building construction. Geometric
ates at once a new design vocabulary for
can also create environmental 'buffer' spaces,
complexity can also be achieved wit h folds,
architecture and a return to an expression of
which are not maintained at the internal tem-
where conventional flat surfaces, which are
the joy of making buildings, as demonstrated
perature of the building but serve as a buffer
straightforward to build, can be formed into
in individual craftsmanship,an approach that
between inside and outside temperature
unconventional facade forms. The recent
can be seen to have been shared widely in
conditions.These spaceswould not require
examples are those by Sant iago Calatrava,
construction before early prefabrication tech-
the same amount of tempered air;but would
Frank Gehry and UN Studio in twisted forms,
niques were introduced in the 1920s.This
provide an opportunity for natural vent ila-
and OM A, Zaha Hadid and LABArchit ecture
approach to design is informed by a balance
tion,all key to reducing carbon dioxide emis-
in folded forms.The approach of folded and
of the specific useof the material system,
sions in buildings. From the point of view of
twisted building forms is a way of introduc-
used to form the building, wit h the sequence
construction, this approach is more complex
ing complex geometr y while maintaining contemporary principles of'repeatability' in
of movement around the building and the
than 20th century construction, but could be
spaces created within.The expression of
achieved with digital tools for design and fab-
order to makethem economicto build using
construction and circulation as'designed'
rication,the to ols of mass customisation.The
a conventional approachto construction. In
elements harnessed to the 'objective' design
possibility of mass customisation of compo-
t his sensethe approach of tw isted and folded
requirements of spatial organisation related
nents allows a departure from the repeated
forms is an intermediary one between the
to programme and site context, can be
rectilinear component so that components
rectilinear repetition of Modernist construc-
a powerful partnership of principles.This
can be more geometrically complex, either as
tion and the emerging construction methods
approach could allow construction to move
individual components or as complete build-
described here.The current approach to
on from 20th century industrial imperatives
ing assemblies. Recent developments in build-
folded and twisted facades requires geomet-
MCH
14
·. -
Computer generated construction system models
ric discipline in order to maintain the repeat-
construction as an additional driving factor.
factured and used in a system in addition to
ability of components, mainly facade panels,
This may be digital, as wit h the possibilities
their essential physical properties.This book
used in conventional construction techniques.
for invention that the t ools bring, or may be
also sets out the construction systems essen-
With the greater introduction of digital fabri-
used for the continued cladding of structural
tial to contemporary architectural produc-
cation tools,the need to maintain a geomet-
frames.This leads the design into a direct
tion, categorised in terms of envelope, struc-
ric discipline will slowly disappear; perhaps
connection with traditional loadbearing con-
ture and environment.The book begins with
making design choices more dependent on
struction, but moving it forward with chang-
a setting out of materials and how they are
the principles of design performance impera-
ing methods of industrial production. Digital
used as material systems and ends with pro-
tive in buildings such as the Einsteinturm dis-
tools allow the performance of a design to
posals for new material systems as an extrap-
cussed in the lastessay. Greater freedom of
be explored and optimised,and be devel-
olation of what is possible in the present and how it could be used in the future.
design from digital tool s will provide greater
oped in order for an individual or a t eam
control and greater responsibility from the
to tackle the fabrication of the component
designer to usethe technology wisely.
which has not been made in a particular way before. Alt ernat ively. a design may usehistori-
Design methodology Current architectural design has a prefer-
cal models, either to endorse the construction methods of existing buildings,to mix old
ence for rectilinear spaces linked in a spatial
and new to create something new, or even
organisation which is also primarily rectilinear;
to advance what is already constructed by
though dependent upon site conditions,
physically adjusting it by using the same mate-
based around the useof rectilinear structural
rial but a different material system.
frames.The design generated is then given
The Modern Construction Handbook
an outward facade expression of materials
sets out these construction techniques, both
formed wit h openingsor wraps as an inter-
traditionally-based and contemporary. all of
face between the internal arrangement of
which evolved during the industrialisation
the building at its immediate site context.
of the 19th century. Essential to this use of
An alternat ive design methodology is to add the use of material systems to that mix:
material systems is an understanding of the physical characteristics of materials as manu-
MCH
15
Materials 0 I Parametric design
Parametrically modelled glazed structural facade
The use of parametric design in architecture
open jointed rainscreens and solar shading
ing is typical or dimensionally constant in the
has been centred around the use of soft-
screens set forward of a wat erproofed back-
external walls.The relationship of inner and
ware that was originally developed for other
ing wall. Rainscreen facade panels comprise
outer skin varies, 50 a set of' rules'is set out
industries. Its primary use in architecture has
a pattern of repeated tri angular panels in a
in the system drawings,then applied t o t he
been t o generate digital models for build-
pinwheel grid,where a set of five triangular
'kit of parts' drawings and the setti ng out
ing structures and external envelope which
panels forms a shape identical in propor-
drawings.
have a complex geometryThe word 'com-
tion to the smallest triangle from which it is
plex' is used t o denote geometries which
formed. In projects such as these,facades are
inner and outer layers are set out in a loose-
are not rectilinear; and therefore cannot be
described in a way that can communicate to
fit relationship between inner and outer skin.
described by plans and sections which can
contractors the nature of a complex three
In projects where forms are either facet-
be extruded in a straight line through the
dimensional form on paper. Elevations of
ted or curved t o create an architecture of
form of the building. Building designs which
such buildings are set out as unfolded or
complex geometry. the means of contro lling
At Federation Square for example, the
do not conform to the rectilinear forms
'developed' facades from a 3D digital model.
the geometry of the building become more
characteristic of Modernism are difficult to
This describesthe scope of the facades and
crucial. In single skin buildings where the
describe as 2D plans, sections and elevations
the t ot al material needed as'kit of parts'
building has a complex form,the exact fit of
in a way which can be communicated to
drawings resemblingthat of anAirfix model
the different components during construc-
thosewho will construct the building. Even
kit. In addition, 2D details describe the 'sys-
tion is critical during construction. In devel-
2D plans, while still a useful t ool, still cannot
tem' as a wall method that could be used
oping such building forms and implement ing
be used to establishthe edge of the external
t o describe how the facades go to gether;
them,the forms need to establish criteria
envelope if the external wall is not vertical,
regardless of its actual application around the
which are fixed, such as floor areaof the
as the position of that wall applies only at
building.Drawings specifically for the facade
different spaces comprising the building,sit e
the horizontal planeat which the plan is set,
systems are needed since the facade con-
constraints, and criteria which are not fixed.
typically at floor level for a form of complex
struction method is devised individually for
Some building designs for complex forms
geometry.Typically. glazing is set above the
such projects. Details of facade conditions at
evolve as a result of more information being
floor level, where plans are typically drawn,
edges, corners, interfaces and junctions with
known about the building, allowing more
but any dimensions on the plan at this point
other parts of the building construction are
of the design to be fixed. Consequently. the
are set at a level difficult to establish on sit e
prepared in the tradit ional way
different criteria of the design can be set
in buildings of complex geometry
Drawings describing the design of com-
as'parameters'which can be related as a
A well-known example of complex
plex geometry of the external envelope are
matrix in the form of a spreadsheet.The
geometry using flat facadesthat do not
of different types:'kit of parts' drawings,'sys-
spreadsheet can be linked to the process
conform to the rectilinear forms of most
tem' drawings, details and setting-out draw-
of modelling the building forms digitally in a
contemporary archit ecture is Federation
ings.This method differs significantly from
parametric design software.Working para-
Square in Melbourne,Australia.The external
the traditional approach of plans, sections,
metrically allows the design to establish what
walls were designed in the form of'wraps'of
elevations,typical details and so on,as noth-
is'fixed' and what will be 'variable' in the
MCH
16
Detailed images of construction system from the same parametricmodel
design development.This approach allows
different requirements can be put into the
to the design of individual buildings, the
a digital design method to evolve. In facade
model at the beginning, with changes in the
possibilities are being seen more widely in
design,the behaviour of the model as a set
digital model showing the corresponding
both fieldsof architectural design and urban
of surfaces can be understood by number;
effect between them all. Facade design of
design.Whe re buildings have been designed
size,geometry and so on.The relationship of
complex forms is often driven by a desire to
asa 'collage' of components which are jux-
the parameters in the design allows the dig-
optimise the construction; often by simplify-
taposed or stacked to gether in a loose-fit
ital model to evolve through an engineering-
ing it by providing as simple a solution as
manner;more contemporary architectural
based method of iteratio n,rather than start
possible without losing t he strength of vision
design is basing itself on a greater integration
the digital design model again each time
or strength of archit ectural expression in
of structure, envelope,environment. space
a new option is explored.This approach
the design. Even in higher budget projects,
and light as ingredient s in a richer mix.
requires some discipline and clarity in the
the need to omit unnecessary complexity
design approach at the outset. which often
of construction and diversity in panel size is
of design allows buildings t o become bet-
makes the parametric design met hod more
important to both reduce costs and attract
ter constructed at the scale of the window,
suit ed t o design development than initial
the most highly qualified companies to work
the bay,the wall, the building and the street
design research. However;parametric plug-
on the project.
to form a continuit y.Where the provision
ins are becoming available for early stage
The possibilities of parametrically-based
This greater level of interdependency
of buildings, roads, natural landscape and
design go beyond the need for evolving a
services infrastructure are considered quite
approach is gaining influence throughout the
single digital model for the main components
separat ely in our industrialised society. the
design process.
of building structure and external envelope.
re-integration of these essential components
With more and more parts of the design
of our cities could eventually become part
design software,ensuring that the parametric
In facade design, where the parametric approach is becoming a primary to ol
forming a single model, the use of a building
of linked parametric models.The interde-
in architecture,the aims vary during the
information model or 'BIM' that sets out all
pendency of building,street. and the natural
different stages of design development.
the components required to make a build-
landscape that was a criticalgenerator ofthe
Outcomes of parametric design can range
ing, is becoming a reality.Whe reas large scale
built forms of the pre-industr ial world, where
from establishing a rationalised or optimised
manufacturing of aircraft, cars, boats and so
the use of energy for both transportation
geometry. reducing the number of panel
on have already usedthis working method
within towns and cities and the responseto
types, restricting the facade assembly so that
for some years, the use of BIMs in building
the built environment played much bigger
it conforms only to the design limits imposed
design is just becoming the norm in higher
roles in the generation of urban form.
by the material systems or facade systems
profile projects. Building information models
An essential aspect of parametric design
being used, ensuring that the floor plates
are now becoming parametric, with the pos-
with digital models is to establish what is
provide a fixed t ot al amount of floor area,
sibility of introducing complex geometry into
import ant in the design and what is much
or ensuring that the relationship with the
the process.
less important; understanding what design
primary supporting structure is maintained without exceeding maximum spans.All these
W hile this approach is aimed primarily
'problem' is being set. and what might be the
at bringing greater control and knowledge
ways of exploring that design.This approach
MCH
17
Materials 0 I Parametric design 2
Parametrically modelled lapped glazed panel covered facade
Embodied energy and digital design
allows buildings to become a much more
parallel, for these choices are as important
closely dependent set of spaces, and building
as the internal organisation of the building,
construction becominga closer expression
the spatial arrangement and relationship to
Two trends in buildingconstruction
of the ideas of space, light and form con-
the site.This brings the choice of materials
which are driving change in architectural
structed within the constraints of a particular
andthe way they are used, or 'tectonics' back
design are concerns about the environment,
material system.A parametric approach will
to the centre of architectural design, rather
and the introduction of computer controlled
also allow much greater int erdependency of
than material and construction-related issues
manufacturing.The effect of building con-
buildings working together as part of a single
being chosen as standard construction meth-
struction on the environment has been of
'organism'- the urban environment of build-
ods afterwards.The result of involving issues
concern since at least the I960s.The effect
ings, streets and public spaces. It is perhaps
of mat erials and construction at a later stage
in building construction is a growing aware-
in the design of public space, and the elimi-
is that the forms of construction used can
ness of the energy required to construct
nation of residual or ill-defined space that
become no more than an outer 'clothing'
buildings, or'embodied energy', and secondly
could be the next major use of parametric
that is deemed appropriate t o the site con-
the energy required t o operate the building
design in digital models.
text and the brief.that it should somehow
when in use.The embodied energy part of
behave well in an architectural sense.The
the equation is concerned wit h both the
limitation of this approach is that the outer
amount of energy needed t o manufacture
Parametric working method
skin has little t o do with the structure and
the materials,transport them t o site,then
parametric design is the ability to develop
envelope mat erials behind it, often forming
install them on sit e.This interest has favoured
different parts of the building design in
the outer rainscreen or covering of a con-
the use of timber,which absorbs C02 dur-
parallel rather than working sequentially
struction systemthat is based on procure-
ing its growth and can be re-planted when cut down for useas a building material.
An essential aspect of working with
from outline design, scheme design, detailed
ment expediency rather than design. Conse-
design and so on. Rather than viewing design
quently. there is a need for material systems
as a series of stages to complete and move
to be involved at early stages of the design
ding' mater ial to an envelope constructed of
on from without significantly changing or
process. Construction methods used for
quite different materials.The idea of'c1adding'
informing what has already been accom-
these essential parts of building design are
buildings involves increasing the number of
However,much timber is used as a'clad-
plished in the design,the design of a building
set out as material systems in the chapters
layers, and has led to a desireto reduce all
is tackled not as something developing as
of this book;each described from a com-
the different requirements of construction
a result of a series of decisions which influ-
mon platform of how the principle mat erial
by making the external walls loadbear-
encethe next decision in turn (from primary
is used to form a system for wall,roof or
ing rather than being cladding panels to a
concerns to secondary concerns and so
structure,and how these might be applied
structural frame.This interest is linked to a
on) but rather of material systems which
to specific strategies of environmental design.
preference for reduced amounts of glazing in
interact and influence one another. A mate-
many building types, where structural frames
rial system for structure,walls, roofs and
were enclosed in highly transparent enve-
environmental design can be developed in
lopes.W hile high levels of glazing encourage
MCH
18
Detailedimages of a glazing systembased on a voronoi pattern
increased levels of natural daylight in build-
become primary tools to reduce energy
material systems shown in this book are
ings,they also admit solargain and provide
consumption for heatingand cooling build-
set out in more detail in the accompanying
poor thermal insulation in all climates.The
ings.This has resulted in the re-introduction
books Modern Construction Facades and
preference for loadbearing construction
of opening windows and of cross ventilat ion
Modern Construction Roofs. From a design
is in some ways a return to pre-industrial
in buildings.
perspective,rather than production of infor-
forms of construction.This interest in a 'leaner' higherperforming construction is
mation for tender or for construction, a 3D
Material systems
model andthe controlled manipulation of that model in relationto the constraints of
possible wit h computer controlled manu-
This Second Edition is aimed as a guide
facturing tools that are linked to drawings
to using material syst ems in contemporary
the material systems such as glass sizes or
and 3D models produced by the design
buildings, with material systems shown as
bending constraints on panels, is as valid as
team.Although in practice it is manufactur-
views of 3D models in order to understand
a 2D section through a building of constant
ers who provide the final drawings for CNC
how they fit together spatially rather than
section. Drawings can show the 'kit of parts'
machines,this is largely a requirement based
treat them as 2D sections.This is because
required to describe the scope of the build-
on how buildings are procured rather than
traditional vert ical and horizontal drawn sec-
ing, which is essential to understanding and
an imperative of the design process. Conse-
tions assume most systems are continuous
setting out how much material is required to
quently, designers can produce a full set of
through their length,that they are extruded
construct the building. From these drawings,
drawings for manufacturers to make a much
in a linear direction either side of the section
the embodied energy required to construct the building can be calculated.
wider range of components than has been
taken. This method of representation also
the case wit h mass production.This link of
assumes that a drawn section, both vertical
The systems of modern construction
design directly to construction, rather than
and horizontal, is a typical condition. W hile
set out in this book suggest a gradual move
re-interpretinga design as a set of drawings
plan, section and elevation explain the over-
forward to methods of production based
that in turn 'get built' is forging a much closer
all scope of the design,junctions of the sepa-
on mass customisation techniques that are
link between design and construction. In
rate planes represented in these drawings
evolving in manufacturing, as well as show-
common with the re-introduction of load-
are rarely resolved in these drawings, leaving
ing how current mass produced material
bearing construction, the use of computer
some coordination issues to be resolved at a
systems can be modified and'diverted' to
controlled mass customisation tools is bring-
later stage. Expressing information as images
the end of producing an architecture rooted
ingthe design of buildings much closerto
from a 3D model allows the system's behav-
in the construction techniques that makeit
the process of constructing them, a privilege
iour to be understood from a geometrical
possible.
enjoyed in the pre-industrial world of con-
point of view of how the components,
struction prior to around 1920.The second
assemblies or panels are set out.
essential aspect of environmental concern
Traditional detail drawings can show
is of the energy consumed by the building
how to describe assemblies in a way which
in use. Natural vent ilation,thermal mass and
is useful when progressing from design ideas
associated issues of night-time cooling have
to a design ready for construction, andthe MCH
19
Materials 0 I Tectonics in metal
Olympic Stadium, Tokyo, Japan. Architect: KenzoTange
Guggenheim Museum Bilbao, Spain.Architect: FrankGehry
Architectural interest in metals in the early
striking form of construction that was char-
industrial world can be seen in the writings
acteristic of later 19th century construction.
of Jean-Baptiste Rondelet, an admirer of
Olympic Stadium,Tokyo, Japan. Archit ect: Kenzo Tange
industrial Britain in the early 19th century.
Stadium of 1964, designed by Kenzo Tange,
His book Traite theorique et pratique de
comprises st eel tension cables in a catenary
l'art de batir discussed architecture from
form, support ed by concrete masts at each
the point of view as comprising a mixture of
end.The complete tent-like structure is used
the visual and the technical rather than the
to support a metal skin,which would typi-
prevailing values of the time of Renaissance
cally be used on a rigid substrate.The metal
architecture, which were primarily of art and
roof skin is actually a series of metal plates
symbolism. He also taught stereotomy, that
welded to gether to form a sealed surface.
is, the art of cutting stones to form complex
W elded metal roofs have been used in more
shapes such as arches and vaults,which is
recent projects for large-scale roofs, but few
enjoying a revival wit h an interest in complex
combine the possibilities of a continuous,
geometry in contemporary archit ecture.As
welded metal surface with that of a skeletal
a construction textbook , the Traite theorique
or tent-like structure that can form a metal
set out many of the components needed
cable structure. Even the cable structure is
for a complete metal construction, such as
made from short lengths bolted together to
prefabricated market buildings, showing an
form a structure that can support the metal
approach towards an integrated assembly
roof plates without an intermediary material.
that follows on from his passion for stereot-
The metal structure and skin is not a'mini-
omy.The metal castings securing the bases
mal' structure, but is certainly one where
of the supporti ng arches illustrate both the
thesetwo components are interdependent.
need for the continuity of material needed
The all-metal roof structure and skin is held
to fix the archesto their bases as well as
in place by a reinforced concrete structure
the elegance associated with their use.The
beneath,whose form echoes that of the
drawings in Rondelet's books are both a
metal structure rather than contrasting visu-
'kit of parts'showing what components are
ally with it.
needed as well as a 3D representation of the assembly of key components.This inter-
MCH
20
In the 20th century, the Tokyo Olympic
More recently. moving structures such as the sail-like canopy at Milwaukee Museum of
est in the physical modelling of junctions
Art, designed by Santiago Calatrava,take for-
rather than in reducing them only t o 2D
ward the visually dynamic qualities of metal
views helps to explainthe more complex
construction.This canopy is used t o provide
nature of t he construction, whose design
solar shading, and moves in order t o provide
approach is embraced rather than simplified.
different experiences of light. Here a folding
The combination of rolled members, castings
structure with a building performing differ-
and connecting brackets creates a visually
ent functions and forming different spaces
Milwaukee Museum of Art. Architect:Santiago Calatrava,
Guggenheim Museum Bilbao, Spain. Architect: Frank Gehry
through moving, is possible because of the
well suited to metal frames, where standard
relative lightness and flexibility of metal,
rolled sections are joined wit h plates or
allowing the possibility of moving parts to be
nodes.The technical success of the system
used to form part of the structural frames
lies partly in creating a limited number of
of buildings. In the Guggenheim Museum
node t ypes which can provide a visually
in Bilbao by Frank Gehry,the architectural
rich construction with a small number of
form of the building is generated as a form
node types or bracket sizes.The use of a
of complex geometry, enabled by the pos-
limited 'kit of parts' can provide a visually rich
sibilities of metal construction, and working
structure and enclosure that can respond
with techniques associated with modelling
to particular design requirements such as
in metal rather than conceivingthis innova-
positioning of openings or links with adjacent
tive form of construction from 20 draw-
structures without needing to be aligned to
ings.ln this sense, the buildings described
a rectilinear grid.
here follow on in the tradition of the Traite
More recently, designs for metal frames
theorique of Rondelet, combining the con-
to support cladding systems have begun to
vention of describing elements in 20 while
use identical polygons which might be twist-
designing in a 30 modelling environment.
ed or pulled out of plane in their geometry
The examples described demonstrate
Milwaukee Museum of Art. Architect: Santiago Calatrava,
and which produce complex shaped surfaces
the ability of metals to form building enclo-
when joined together. In addition, the 'cold
sures of complex form in a single material
bending' of metal panels to cladding systems
where structure and skin are a visible part of
can create more complex forms for enclo-
the architectural design. In more rectilinear
sures from flat sheetor profiled sheetwit h-
building designs, steel frames can be used
out the need for any special manufacturing.
which do not necessarily produce a rec-
This can combine the benefits of more com-
tangulargrid of cladding panels across their
plex steel frames that are straightforward
surface. Federation Square in Melbourne,
to construct with metal wall systems that
Australia, designed by Lab Architecture uses
are usually more associated with rectilinear
a triangularspace frame as a point of depar-
forms wit hout changing the way such enclo-
ture from which to create a structure which
sures are constructed. However; for all these
gently departs from this principle, creating
examples of tectonics in metal, the designer
junctions which form moment connections
is obliged to set out the construction of the
rather than the pin joints associated with
structure and enclosure in a more detailed
triangulated frames.This approach allowed a
waythan that expected for more generic
range of glass panels to be added which are
forms of construction,just as Jean-Baptiste
still based on a triangulargrid.This method
Rondelet set out examples from hisTraite
of startingwith regularforms of construc-
theorique, completed in 1817.
tion and working with their geometry is MCH
21
Materials 0 I Steel
Federation Square, Melboume,Australia.Architect: LAB Architecture Studio
Steel is an iron-based metal alloyed with small amou nts of other elements , the most
Guggenheim Museum, Bilbao, Spain..Architect: Frank Gehry
making it less susceptible to shock damage. (The Eiffel Tower; in Paris, was one of the
impo rtant being carbon .The three main
last large structures to be constructed in
forms of steel used in th e building industr y
wrought iro n). By the end of the 19t h cen-
are sections,sheets and castings. Stee l sec-
tury.both materials had been superseded by
t ions are currently formed using a ro lling
steel. Stee l was first prod uced aro und 1740,
pro cess. It can be extruded to form complex
but was not available in large quant ities unt il
sections, but th is curre nt ly has only limited
Bessemer invented his converter in 1856.
applicat ions due t o th e high pr essure need-
Thi s device introduced a method of blasting
ed to extrude st eel.Aluminium is a much
air into th e furn ace (hence blast furn ace) t o
soft er materi al, making it easier t o extr ude.
burn away t he impu rities th at inhibite d th e
Even w hen alumi nium is alloyed wit h ot her
extraction of a purer iron . By 1840, standard
materi als such as bro nze, the extrudable size
shapes in wrought iron, mainly ro lled flat sec-
of sections dro ps dramatically Extrusions in
ti ons, t ees and angles were available wh ich
steel cannot exceed shapes th at fit into a
could be fabricate d int o structural compo-
circle approximate ly 150mm (6") in diameter.
nents w hich are then assembled by rivet ing
This is too small for structural sections, but
them together. By 1880,the rolling of steel
the ir smooth appearance makes them suit-
I-sections had become wi despread, leading
able for components such as stiffeners in
the way to th is material event ually replacing
curtai n wa lling (to provide a fin t hat is visu-
wrought iron as a material of choice .
ally mo re refined th an an I-sectio n or a t ee). C urrently.it is still far easier t o roll steel secti ons than to extrude th em. Historically, cast iro n and wro ught iron
Guggenheim Museum, Bilbao, Spain..Architect: Frank Gehry
MCH
22
Production process of raw material There are several steps in the manu-
were the forerunner s of stee l. Cast iron,
facture of steel. First, iron is refined from
a brittle material w it h high compressive
ores containing iron oxide .The iron ox ide
st rength, came into general use as a build-
is heated in a blast furna ce until it is mol -
ing mater ial at th e end of th e 18th cent ury.
t en, using carbon as a reducin g agent.T he
w hile wro ught iron was develop ed some 50
mo lte n materia l is po ured into moulds to
years later. Wrought iron is a mo re ducti le
prod uce pig iro n. It is then re-heate d to
mate rial and has greater tensile strengt h,
remove impur ities, including carbon, to make
Federation Square, Melbourne,Australia. Architect: LAB Architecture St udio
cast iron th at has a carbon content of 2.4
· High st rength in both ten sion and
per cent t o 4 per cent. Stee l is produc ed
com pression.
by reducing the carbon cont ent to approx i-
• High stiffness.High rigidity in both t ension
mately
0.2 per
cent, w it h mate rials such as
and compression.
manganese and silicon added to halt the
· Its appearance is smo ot h in sheet form ;
oxidation proce ss and stabilize the carbon
rougher of t exture in roll ed sections and
content. It can be pou red w hen molten to
castings, even wit h paint applied.
make castings o r formed into ingots to be
• Lighter th an an equivalent structural mem-
rolled into sheets or sections.
ber in reinforced concrete . · High duct ilit y,deforming long before it fails.
Properties and data
· High impact resistance.
The main prop er t ies of structural carbon
· High heat conducto r.
steels are as follow s:
• High electrical conductor.
lAC Headquarter s, NewYork. USA.Architect: Frank Gehry
· Thermal expansion approx imat ely half th at Density: Mild steel = 7850 kg/m3 (490 Ib/ft 3)
of aluminium. · Suscept ible to cont inuous rusting, excluding w eat hering steels.
D esign strength: A pp rox imat e ran ge 275 N/mm2 to 800 N/mm2
· Low fire resistance.
(5.7 x 106 to 1.6 x 107 Ibf/ft 2) Young 's modulus = 205 kN/mm 2 (4.2 x 109 Ibf/ft 2)
made in th ree types called 'grades' increas-
Coefficient of thermal expansio n
ing in design strength from 275N/mm2 t o
= 12 x 10-6 K-I
(6.7 x 10- 6 OF-I )
Thermal conductivity =
o
45 W /m
(26 BTU/hr.ft.0F) Specific he at capacity=
Material selection Hot ro lled structural mild steels are
400N/mm 2 (5.7 x 106 Ibf/ft 2 t o 8.3 x 106 Ibf/ft 2 ), vary ing slight ly in different regions
C
of th e world. High strength steels can reach
480 J/kg
o
C
(0.I I
BTU/lbOF)
design strengths of 800N/mm 2
(1 7.6 x
106 Ibf/ft 2). Since th e Young's Modulu s is
..... .....
II ...
constant for all the se ty pes, th e strength of For compariso n w it h oth er materials, steels
mater ial increases but th e st iffness remains
have th e follo win g general properties:
constant. Steel also increases in cost with
The Barcelona Fish, Barcelona,Spain.Architect: Frank Gehry MCH
23
Fisher Center for the Performing Arts, Bard College,
Federation Square, Melbourne, Australia. Architect: LAB Architecture Studio
Hudson Valley, New York. Architect: Frank Gehry
higher levels of strength, both in the cost of
and castings. Steel can also be sawn and
This can be done by either encasing the
the raw material and in the working of the
drilled. An essential characteristic of steel-
material in concrete, by enclosing it in a fire
material. In addition, as strength increases in
work is that it will continue to rust if a sur-
resistant board, or by coating it in intumes-
the material, welding becomes more difficult
face protection is not provided. When drilling
cent paint. A spray-applied coating that yields
and consequently more specialized. In some
or cutting the material, the newly exposed
a very rough, fibrous surface appearance is
high strength steels,which undergo heating
surface requires protection, which is par-
often used where the steel frame is con-
and quenching during their manufacture, the
ticularly important if the material has been
cealed behind finish materials.
effects of welding could potentially undo the
factory coated prior to drilling and cutting.
work of manufacture if sufficient care is not
The economic protection is galvanising, a zinc
taken. Standard rolled sections are manufac-
coating that is corrosion resistant, applied to
Coatings Many factory applied proprietary sys-
tured in the low to medium strength grades
the steel in a hot dip bath or as a flame spray
tems are available for coating steel; the most
but higher strength steels are made mostly in
Galvanising occurs after fabrication of steel
common types are thick organic coatings
the form of plate, due to lower demand for
components to cover all the welding and
and powder coating. PVDF (polyvinylidene
their use. Consequently, compound shapes
drilling.This process can cause distortion of
di-fiuoride, also called PVF2 in Europe), is
for structural components, such as beams
smaller steel components, so may not suit all
sometimes used, and is discussed further in
and columns, must be specially fabricated.
types of fabrication. The appearance of galva-
the section on aluminium. Organic coat-
Cold worked mild steels are used for
nising when new is a mottled shiny grey,turn-
ings provide high levels of protection against
much smaller scale structural components
ing to a dull grey with weathering as the zinc
corrosion but have a distinctive orange peel
such as lightweight structural framing in metal
oxidizes. Its visual appearance is often not
texture. They are applied to steel coil, from
framed housing and low-rise commercial
suitable for exposed structural steelwork or
which sheet is cut, during manufacture.These
buildings, used mainly in the USA, and dry-
cladding in buildings, where paint coatings are
finishes have methods of touching up surfaces
wall partitioning. Cold-formed steel sections
more common. Flame sprayed aluminium can
that become exposed or are damaged dur-
are made from structural carbon steel to
be used as an alternative to galvanising. Paint
ing installation, but colour matching remains
form sheets or strips approximately l.5mm
can be applied by hand on site or in a factory
an important consideration in successful re-
(1/ 16in) thick. Complex sections are formed
as part of a proprietary finish. Care must be
touching.
by folding and pressing,rather than rolling
taken to ensure that touching up on site of
which is the case with hot formed sections.
visible components is done in controlled con-
Working with the material
ditions that ensure the finish both matches
Sections and sheets can be curved to
and blends into the surrounding coating.
small radii. Bolting and welding are the most common methods of joining sections, sheets
MCH
24
When used as primary structure in a building, steelwork requires fire protection.
Recycling Steel can be recycled at reasonable cost, and requires much less energy than the original production process.
Federation Square, Melbourne,Australia.Architect:LABArchitecture Studio
Stainless steel
Dancing House Prague, Czech Republic .Architect: FrankGehry
Stainless steel has the following general
variety of rolling techniques from smooth to
properties:
textured, in an appearance from matt to pol-
contains between approximaately I I to 25
• Highly resistant to corrosion and usually
ished. In addition, the sheetcan be coloured
per cent chromium,together with nickel
requires no further coatings.
as part of the manufacturing process.
in some types,giving it properties that are
· Higher fire resistance than carbon steels.
Stainless steel is an alloy of steel which
distinct from carbon steels, the main one
• A risk of bimetallic corrosion at the junc-
being a high resistance to corrosion without
tion of stainless steel and carbon steel when
the need for an additional coating. Since the
they are used together.
material is considerably more expensive than
Separation at junction is usually required,
the traditional pattern of fabrication for
carbon steels, stainless steel is most com-
such as a nylon or neoprene spacer.
carbon steel members except that more
Working wrth the material The fabrication of stainless steel follows
monly used in small building components and
use is made of pressing and bending to form
in cladding panels where durability is a prime
suitable shapes. Fabrication of stainless steel
Material selection
concern.
Although the material develops a thin
should be kept entirely separate from that of carbon steel to ensure that the processes
Properties and data
oxide layer that protects it from further
of cutting and grinding do not cause impreg-
Density
corrosion, different grades of stainless steel
nation of carbon steel particles onto the
are available to suitthe severity of exposure
stainless surface, which can lead to rusting.
= 7850 to 8000 kg/m 3 (490 to
500 Ib/ft 3) Young's Modulus : In the longitudinal direction 190-200kN/mm 2
=
from polluted urbanto maritime to rural
Fabricated elements should seek to eliminate
environments.A limited range of standard
standing seams or edges where water can
sections is available and usually in small
collect, in order to avoid crevassing corro-
(3.9 x 109 to 4.1 x 109 Ibf/ft2)
sizes only. The need for a high degree of
sion. Stainless steel has high ductility which
In the transverse direction 195-205 kN/mm 2
fabrication of members can make construc-
gives the material excellent resistance to
tion time slower than that for carbon steel
impact loading.
=
(4.0 x 109 to 4.2 x 109 Ibf/ft2)
applications. For example, plate is folded to
Coefficient of thermal expansion
form angles and tubes,and hollow sections
=I 3 x I0- 6 to 17 x I 0-6 K-I (7.2 x 10-6 to 9.4 x 10- 6 OF-I)
are formed by bending and seam welding.As wit h carbon steels, the high strengths types, which have been heat-treated,are more difficultto weld, as the process can undo the heat strengthening. Different finishes are available which are achieved by using a MCH
25
Materials
0I
Alum inium
St Paul's Place car park,Sheffield, UK Architect Allies & Morrison
St Paul's Place car park,Sheffield, UK.Architect:Allies & Morrison
Aluminium was first produced in 1825,and
steel, aluminium is a material that can be
by the late 19th cent ury a method had been
extruded, rolled and cast into complex
found to mass produce the material by the
shapes: plates, sheets, extrusions and castings,
electrolysis of alumina and cryolite.
Properties and data Production process of raw material
The main properties of aluminium alloys are as follows:
Aluminium is madefrom bauxite, which
ImperialWar Museum North, Manchester, UK, Architect: St udio Daniel Libeskind
is essentially an hydrated alumina, or alu-
Densit y = 2700 kg/m3
minium oxide, Mined bauxite is treated
( 169 Ib/ft 3)
chemically to remove impurities and obtain
Design strength
alumina,which is aluminium oxide.This is then reduced to aluminium by electrolysis,
Heat treate d = 270 N/mm2 (5.6 x I0 6 Ibf/ft 2) for extrusions
Becausealuminium has a very high melting
and 235 N/mm2 (4.9 x 106 Ibf/ft 2) for
point (2450°C) it cannot be electrolysed on
plate
its own,and so it is dissolved in molten cryolite.A high electric current is passed through
Fully softened= 105 N/mm 2 (2, I x 10 6 Ibf/ft 2) for plate
the alumina-cryolite mixture at around
Young's Modu lus = 70 kN /mm 2
IOOO°e, and the molten aluminium is tapped
109 Ibf/ft2)
off,Aluminium alloys are either formed directly, followed by continuous casting, or
Coefficient of t hermal expansion = 23 x 10-6 K- I ( 12.8 x 10-6 O F-I)
are cast into solid ingots.The metal is t hen
Thermal conductivity =
cast into ingots which form the basis for
200W/m oC
producing aluminium alloys. Pure aluminium
( I 16 BTU/hr.ft,0F)
istoo soft for structural use and is therefore
Specific heat capacit y = 880 J/kg C (0.2 1
combined with other metals to form alloys
BTU/lb OF)
to increase its strength and hardness,though reducing its ductility. Magnesium, silicon and manganese are the most common additives, Aluminium alloys make strong, lightweight structural components. In common with MCH
26
o
( 1.4 x
Selfridges. Birmingham,UK.Architect: Future Systems
For comparison with other materials, aluminium alloys have the following general properties:
Material selection Pure aluminium and its alloys are in two broad groups:the non heat-treated alloys. also called fully softened alloys. whose
· Lightness, weighing about a third that of
strength is produced from being cold
steel.
worked. andthe heat-treated alloys whose
· High t ensile strength. similar to that of steel.
strength is produced by heat treatment.The
· High impact resistance. (compared to steel)
non heat-treated types are generally not as
· High corrosion resistance, but alu-
strong. but have better corrosive resistance.
minium requires protective coating in very
Structural useof aluminium alloys is
polluted or severe atmospheric conditions.
limited by two significant disadvantages: they
· Coatings are not applied solely for appear-
are more expensive t o manufacture than
ance.
steel andthey deform more easily under
· High heat conduction.
load.Aluminium alloys are more elastic than
· High electrical conduction.
steel.restricting their useto components
· Poor stiffness.
and assemblies where this is not a constraint.
· Low resistance to soft impact, but absorbs
Since the Young's Modulus of aluminium is
impact energy which localises damage.
one third that of steel, buckling is an impor-
(Whereas a soft.or low level impact, such as
tant issue in its structural use.The potential
a kick, would not damage a steel panel. it will
of this material as a full structural material
dent one in aluminium.
in buildings is beginning to be recognised.
· A high impact, such as a car reversing into
The Media Centre at Lord's Cricket Ground,
a panel. would cause a large steel panel to
London.England. is a recent notable example
buckle across its entire height and length, but
becauseof the full structural use of aluminium
one made of aluminium will again dent only
in a large-scale building frame.
around the impact area). · Thermal expansion approximately twice that of steel. · Poor fire resistance.
Working with the material On exposureto the atmosphere. aluminium forms a protective coating of aluminium oxide. Under adverse conditions.the oxide film can break down locally, but it usu-
MCH
27
Materials 0 I Aluminium
Iris Dome at EXPO 2000 in Hanover, Germany
OitaStadium, Japan. Architect:Kisho Kurokawa & Associates ally reforms to a greaterthickness preventing
treatment in the other alloy types.Since
and applying an electrical current,creating an
further attack.Aluminium can be exposed to
the design strength of the fully softened
oxide layer integral wit h the underlying metal.
the weather; in non-polluted environments
alloys is halfthat of the heat-treated types,
The anodic film is porous and must be sealed.
and awayfrom maritime conditions, without
the section sizes used in welded aluminium
This is done by immersing the anodised alu-
the need for additional treatment provided
structures can often be similar to that of
minium in boilingwat er or steam.The ano-
the surface is maintained. Over time, it loses
comparable steel structures, but wit h con-
dised coating can be dyed; the sealing then assists its colour-fastness. Anodising should
its initial bright appearance and assumes a
siderably less weight.The design strength of
dull grey sheen. Aluminium should be cleaned
the heat-treated alloys, which is similar to the
be carried out after welding.The process of
regularly to avoid pits forming in the material
bottom end of the design strength of steel,
welding would otherwise break down the
surface. However; one way to avoid this isto
can be exploited in extrusions, which require
anodising process at heat-affected locations.
anodise or paint the material with a propri-
no welding in their manufacture. Extrusions
Broken-down anodising could result in weld
etary coating.
can be usedto form complex profiles, such
impurities that would impair its structural
as those needed in window sections or walk-
effectiveness.
Aluminium is susceptible to electrolytic corrosion in contact with certain materi-
way decking, and be much lighterthan an
Aluminium's natural finish, often referred
als such as copper:Therefore direct contact
equivalent member in steel.The material can
to as mill finish, can be worked to produce
wit h copper and copper-rich alloys, such as
also be cast to form complex shapes that are
a polished, ground or brush-grained finish.
brass and bronze is avoided and the material
more economic in large quantities than an
Etching gives a matt and non-directional finish
should be used in a way that water does not
equivalentfabricated component.
with no direct refiections.Anodising gener-
fiow onto it from copper: However; water fiowing from aluminium to copper or lead is not harmful.There is no corrosive action
Anodising Anodising produces a fine translucent
ally follows these processes, which increases durability and enhances long-term appearance. Brightening is not suitable for architec-
between aluminium and zinc or zinc coat-
film over the surface of aluminium.The ano-
tural alloys which are only 99.5% aluminium
ings and galvanised surfaces. Some timber
dising process results in the replacement, by
because the brightening is not uniform.
preservatives contain compounds harmful
electrochemical means, of the metal's natu-
Chemical brightening on other alloys dis-
to aluminium. Untreated timber affects the
rally formed oxide film by a dense chemi-
solves and fiattens surface irregularities found
material to a much lesser extent.
cally resistant artificial film many times the
in extruded or sheetaluminium surfaces, and
thickness of its natural equivalent.This film
produces a mirror finish with a very high
Aluminium can be cut and drilled, riveted, bolted, screwed and glued.The material can
is extremely hard, gives added protection
refiectivity It can be anodised without dulling
also be welded. However; welding is usually
against abrasion,and reduces the adhesion
the surface.
done using the fully softened alloys, since
of dirt particles.Anodising is carried out by
this process can undo the work of the heat
immersing the aluminium in an electrolyte
MCH
28
Luigi Colani designs
Coatings Aluminium can be coated in a wide range of colours through the use of pro-
Recycling Aluminium is one of the easiest and cheapest materials to recycle. The conversion
prietary processes. Plastic coatings provide
of scrap backto high-grade metal requires
a durable paint surface; polyester powder
only about 5% of the energy needed to make
coating is one of the most common finishes.
the same amount of metal from bauxite.
Plastic coatings are dip-coated, sprayed or electrophoretically deposited underwater.The electrostatically applied finish ensures that an even coat is built-up on the metal.These paints fade and losetheir shine with time, though the change is slow and even. PVDF (polyvinylidene di-fluoride),also called PVF2 in Europe, and powder coatings are most commonly used. PVDF is a spray-applied finish, which is highly resistant
The Lightbox,Woking. UK.Architect: Marks Barfield Architects
to fading in sunlight, making it very suitable for external use where colour stability is an important consideration such as in wall cladding. Powder coating is applied in an electrolytic process that provides a softer. and less expensive coating than PVDF. It is not as resistant to fading in sunlight, but is a harder finish and less expensive, making it suitable for both an economic external finish and excellent for internal use.All these finishes have methods of touching up surfaces that become exposed or are damaged during installation or use, but colour matching remains an important consideration.
The Public.West Bromwich.UK,Architect:W ill Alsop
MCH
29
Materials aI Copper, zinc and lead
Copper cladding in use
Properties and data
(65.4 BTU/hr.ft.OF) Lead: = 35W/mK
Density :
(20.2 BTU/hr.ft.OF)
Copper = 8900 kg/m3 (560 Ib/ft 3) Zinc = 7 140 kg/m3 (445 Ib/ft 3)
Specific heat :
Lead = I I,340 kg/m3 (705 Ib/ft 3)
(0.093 BTU/lb OF)
o
Copper: = 390 j/kg C o
Zinc: = 385 j/kg C Tensile st rength:
(0.092 BTU/lb OF)
Copper = 2 16- 355 N/mm2 (4.5 x 105 to 1.0 x 106 Ibf/ft 2)
Lead: = 388 j/kg C
o
(0.093 BTU/lb OF)
Zinc = 139-216 N/mm2 (3.8 x 105 to 5.9 x 105 Ibf/ft 2) Lead = 15-18 N/mm2
Material selection
(3. 1x 105 to 3.8 x 105 Ibf/ft 2)
zinc and lead are the most widely used met-
Apart from steel and aluminium, copper, als in the building industryThese metals are
Copper claddingin use
You ng's Modulus : Copper = I 17-132 kN/mm2 (2.4 x 109 to 2.8 x 109 Ibflft2) Zinc = I 10 kN/mm2 (pure) (2.3 x 109 Ibf/ft 2) Lead = 15-18 kN/mm2 (3. 1 x 10 8 to 3.8 x 108 Ibf/ft 2)
produced as sheets of up to approximately one metre (3ft 3in) wide sections and castings. All three metals have excellent weatherresisting properties, however, they are susceptible t o attack by pollutants such as acids. Their use is restricted to non-structural metals and alloys, because none has the strength or rigidity of steel,or the combinat ion of
Coefficient of thermal expansion :
strength and lightness of aluminium.They are
Copper = 17 x 10- 6 K- I across grain (9.5 x 10- 6 OF-I ) Zinc =23 to 40 x 10-6 K-I (across
generally used as cladding materials for walls
grain) ( I2.8 x I0-6 to 22.5 x I0-6 0F- I) Lead 29.5 x 10-6 K- I (across grain)
wiring.
( I 6.5 x I0-6 0F- I)
Working wit h these materials
and roofs. Copper is also used extensively for water supply pipework and in electrical
Copper is stro ng in tension,tough and
MCH
30
Thermal conductivity :
ductile, but is not as malleable as lead.The
Copper: = 300 W/mK
material has a shiny red/yellow colour when
( 173 BTU/hr.ft.OF)
new, slowly developing a protective sulphate
Zinc: = 113 W/mK
layer on its surface when exposed to the
Zinc cladding in use
Copper cladding in use
atmosphere.This patina has a characteristic
Zinc is a durable material, although it is more
can be cut,drilled, nailed, welded in a proc-
green colour which has a fairly consistent
brittle than copper. It is manufactured as a
ess called leadburning,and soldered with
colour and texture. Copper is available with
white coloured metal, but when exposed
hand power tool s. Due to its lackof rigidity,
a pre-weathered, or pre-patinated finish
to the atmosphere a carbonate is slowly
lead sheet is most commonly jointed by
which is chemically induced.This finish varies
formed which produces a protective coating
dressing it over rounded timber battens or
slightly from naturally weathered cladding.
that isgrey-white in colour. The material has
rolls.W here standing seams are used, they
Well maintained copper cladding, which has
a linearthermal expansionthat is similar to
often incorporate a steel angle to keepthe
oxidised atmospherically, will lastfrom 30 to
lead and higherthan copper.
line of the joint straight and vert ical. Lead is
50 years.
Zinc can be cut,drilled,nailed, welded
There is a variety of copper types avail-
and soldered wit h hand power tool s, mak-
alloyed with tin to form solders for jointing and sealing.
able, each of which is suitable for a particular
ing it reasonably versat ile for use on site. Its
task. For instance, deoxidised copper is suita-
rigidity makes it well suited to standing seam
ble for welding, while fire-refined tough-pitch
joints. W ell maintained zinc cladding can last
copper; with its tougher resistance to cor-
for between 30 and 50 years. Zinc is liable
other;rainwater running from one to the
rosion, is used for cladding. Otherwise, both
to attack from copper alloys, so that rainwa-
other can cause corrosion by electrolysis.
have similar properties. Copper forms a high
ter running off copper should be avoided.
Run off from copper and zincwill attackcast
proportion of metal in alloys such as bronze,
Apart from its use in alloys, zinc is used as a
iron, mild steel, galvanised steel and alumini-
which is primarily a mixture of copper and
protective coating to steel, applied through a
um. In addition, copper will attack zinc. Lead
tin. Brass is primarily a mixture of copper
process of galvanising and sherardising
is much more resilient and does not attack
and zinc,and aluminium bronze is primarily
Lead
is an extremely durable,ductile
Electrolytic action W hen different metals are near each
other metals wit h the exception of alu-
a mixture of copper and aluminium. Cop-
and malleable material, making it extremely
minium when used in marine environments.
per can be cut,drilled, nailed, welded and
useful for roof coverings and flashings in
W hen roofs or walls are made from either copper or zinc, typically other metals are not
soldered with hand power tools, making it
traditional roof construction. However; while
versat ile for site-intensive work.W hen used
its relative softness allows lead to be formed
usually used in adjacent components, such as
as cladding,joints between sheets are made
into complex shapes, its lackof rigidity
gutters and flashings,where wat er run off is
by foldingthe edges together.This method
means that a supporting material must be
likely to occur.
takes advantage of the fact that copper can
provided beneath it.Timber boards are most
be bent alongan edgefairly easily, but is rigid
commonly used for this. Lead has low resist-
enough to remain folded.
ance to creep.
Zinc
sheetfor cladding is made from
On exposure to the atmosphere,a pro-
either commercial zinc orfrom an alloy of
tective coating of lead carbonate is slowly
zincwith small amounts of copper and tita-
formed on its surface.This gives weathered
nium added.The properties ofthe two types
lead a dull grey appearance . Lead is a poi-
are similar;but zinc alloy has better tensile
sonous material, leading to increased aware-
strength and resistance to creep, which is
ness of the dangers of water run off from
long-term plastic deformation under load.
lead cladding reaching the water supply. Lead
MCH
31
Materials 0 I Tectonics in glass
Paris Metro station canopy, Paris, France.Architect: Hector Guimard
An essential use of glass in buildings is
Paris Metro station canopy, Paris, France.Architect: Hector Guimard
opportunities for designers to use large
ing importance of thermal insulation and a
glazed panels in facades. However, since
reduction in the energy consumed to temper
most glazing is made in double glazed units,
the internal environment of buildings, the use
glass panels do not often achieve these sizes
of singleglazing with thin supporti ng frames
due primarily to issues of deflection under
without thermal breaks, is no longer used
wind load and the dead weight of the glass.
in most new buildings except where, for
A 3000mm wide double glazed unit, storey
example, the spaces enclosed by the glass are
height, weighs around 6S0kg, making it diffi-
considered to be external and serve only as
cult to lift into place using conventional lifting
canopies, or in the outer screens to double
systems for glazed units and even more dif-
facades. In these semi external applications,
ficult to consider moving it around by hand.
the visual lightness afforded by lightweight
Double glazed unit s of half their size can be
steel supporting structures can still echo t he
difficultt o manhandle on site. In addition to
glazed structures of t he early 20th century,
the weight of glass, its size is an important
such as the canopies to Metro stations in
consideration when designing wit h the mate-
Paris by Hector Guimard.Theses canopies
rial. The six metre by three metre sheets,
have glass panels which have no support
called 'jumbo' sheets, are required to be cut
on the outer edges,allowingthe supporting
economically to avoid waste.This makes glass
metal structure to take precedence.This pref-
economic for the ISOOmm wide panels pre-
erence for the expression of the supporting
ferred in office buildings, but does not restrict
structure at the visual expense of the glass
their cutting to rectilinear panels.Triangular
has been a theme in glass tectonics through
panels can also be economic if cut without
the 20th century In the Guimard canopies,
significant waste, as can other shapes which
covers for lights to illuminat e the entrance
frt the jumbo sheet format.
32
In wall construction, where glass is used
ing structure being almost a container for t he
in most quantity in most buildings,the mate-
exquisitely formed lamp covers.The use of
rial is fixed either along its edges or at point s.
glass and metal is finely balanced both t echni-
The use of edge restraint results in a frame
cally and visually,though the richness of the
behind all glass edges, but point fixed glazing
forms were only gradually accepted as being
allows the material to become visually domi-
of architectural merit.
nant,allowing it to be seen almost as a con-
Glass is manufactured in sheets of float
MC H
laminat e glass at this size, providing more
in double glazed units.With the increas-
have a form of their own, with the support-
Bilbao Metro entrance, Bilbao,Spain.Architect: Foster & Partners
Paris Metro station canopy, Paris, France.Architect: Hector Guimard
tinuous plane of glass rather than as an infill-
glass approximately 6000mm x 3000mm,
ing material. The glazed screen in the Dancing
which is typically much larger than can be
House by Frank Gehry in Prague, completed
used as single sheets in buildings. Some
in I996.This contrasts with the use of glass at
glass manufacturers are ableto temper and
Federation Square by Lab Architecture, com-
187 - 195 Oxford Street,London, UK.Architect: Future Systems
Swiss ReTower, London, UK.Architect: Foster& Partners
pleted in 2003, where the supporting frames
reducetheir U-value andto reduce solar
dominate as the language of the tectonic,
gain.This makes double glazed units increas-
with the glass as an infill material. An advan-
ingly energyefficient. and the introduction
tage of the framed approach is economy, as
of argon gas into the void between the glass
the double glazed units can be fitted directly
panels further increases their thermal per-
to the supporting frame. Bolt fixed glazing
formance.When used in curtain walling,the
requires the glass to be drilled before any
framing is typically much poorer in thermal
tempering is done, making it expensive to
performance, bringing the U-value from a
use, though recent examples use bolt fixings
typical 1.1 W /m2K up to a typical 2.0W/m2K,
that are bonded to one face of the glass, or
depending on the framing type.The thermal
drilled through only one sheet of the double
break in curtain wall systems is a structural
glazed unit.An alternative approach isto
component at present. so finding a much
clamp the glass by passing plates through the
higherperformingthermal break is not with-
joints between the units. Consequently, the
out its difficulties. In very cold climates, triple
design and position of the clamps becomes a
glazed units are being introduced, though
primary issue in the design of the system as
there is still a limited condensation risk at the
the visual impact of a surface covered with
edges of the unit where the perimeter spac-
small clamps creates a kind of'point cloud'
er conducts greater amounts of heat energy.
of fixings across the surface of the glass wall
A development over the past 10years has
or roof
been in the introduction of so-called 'super
The curving of glass has undergone some
neutral'glasses in double glazed units which
development. at leastin the quality of pro-
have high solar control performance com-
duction,in recent years. Specialist companies
bined with higherlevels of transparency than
around Europe now offer single curved glass
was formerly the case with so-called 'body
panels in both tempered and laminated glass.
tinted' glasses. Superneutral glasses have
Some companies around the world will now
a colour which is visually not as strong as
provide double curved panels, as used at the
the older generation of body tinted types,
Nordpark Cable Railway in lnnsbruck, Austria,
though these are still available. Superneutrals
which form a durable and reflective surface
allow more daylight transmission than their
finish for canopy enclosures.The ability of
forerunners, but in locations where there is
glass to be curved, coated andtempered is
considerable exposure to the effects of the
making it more of a sculptural material again,
sun an additional outer screen of solar shad-
following in the tradition of the Guimard
ing panels might be used.
Metro entrances. The useof glass in double glazed units
Dancing House Prague, Czech Republic Architect: Frank Gehry
A recent development in glass design has been the introduction of all-glass structures,
allows the encapsulated inner faces of the
where glass components are connected
glass to have coatings applied to them to
together by silicone bonds.The silicone
Dancing House Prague,Czech Republic Architect: FrankGehry
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Materials 0 I Glass
Federation Square, Melbourne, Australia, Architect: LAB Architecture Studio
Federation Square, Melbourne, Australia. Architect: LAB Archit ecture Studio
Nordpark Cable Railway.lnnsbruck .Architect:Zaha HadidArchitects
serves as both adhesive and sealant, provid-
ment across the extent of the walls. Some
ing weathertight enclosures.The scale of use
projects, particularly for glazed roofs, have
to date has been modest, with single storey
used a large number of glass panel sizes in
conservatories,walkways,canopies and glass
order to suitthe structural geometry of the
floors as the primary examples of their use.
roof form, but these are typically quantified in
Mostapplications have additional mechanical
detail by the design team in order to control
fixings to overcome concernsabout the long
cost.
term durability of all-glass structures, but this
A recent alternative to the curving of
varies from projectto project. An alternative
glass as part of the manufacturing process
to the all-glass structure is the cladding of
has been to 'cold bend' glass sheets on site,
conventional structures or walls in opaque
typically as part of a stick (site assembly
rainscreens.This method uses screen printed
based) glazing system.The amountsto which
glass which istypically silicone bonded to a
the glass can be pushed at the corners to
backing frame ,then hooked on, or fixed back
take up a curved form across its surface is
to, a carrierframe behind.This use of glass
limited, but curves in glazed walls and roofs
as an external rainscreen allows the void
are often modest, making the idea of cold
between the glass and the external face of
bending more attractive to contractors.
the backing wall to have lighting, creating a glow to an otherwise opaque or utilitarian facade, with the benefit of creating some lighting for safety of users around the building.
The manufacture of float glass is the first stageof production. Float glass is made by
One of the main changes in the use of glass in facades and roofs is a gradual move
Federation Square, Melbourne, Australia. Architect: LAB Architecture Studio
Production process of raw material
pouring molten glass onto a bath of molten tin.The glass floats on top and is drawn offas
away from entirely rectilinear glass panels to
it solidifies. It is available in thicknesses ranging
those that deviate slightly from it.These can
from 2mm to 25mm (I/8in to Iin).
rangefrom parallelogram shapesto triangular
Most float glass has a green tint caused by
to diamond patterns in glazed facades, but
small amounts of iron oxide in the glass.Add-
all are based on the need for repeatability
ing different oxides to the mix during the
of glass unitsize in order to make the glass
manufacturing stage can alter the tint of the
economic to manufacture. In addition, glazed
glass.
walls are required to move in relation to their supporting structure, and must be able to move from one panel to the next.This further encourages the panels to be of the same size in order to ensure that the movements have a consistent 'behaviour' of moveMCH
34
Properties and data
Density: Float glass = 2520 kg/m 3 (158 Ib/ft3) Tensile strength: Float glass = 35-55N /mm 2 (7.4 x 107 Ibf/ft2)
Nordpark Cable Railway. Innsbruck .Architect:Zaha HadidArchitects
Compressive strength:
=
3800--4670 N/mm2
Glass block sizes for external walls:
Float glass ( 1.0 x 107 to 1.2 x 107 Ibflft 2)
(8in x 8in x 4in thick (imperial)
Young's Modulus:
146 x 146mm (nominal 6in x 6in)
Float glass 70 kN/mm 2 ( 1.4 x 109 Ibf/ft 2)
197 x 197mm (nominal 8in x 8in)
Coefficient of thermal expansion 23 x 10- 6 K-I (12.8 x I0- 6 F-I)
Typical thickness 98mm (nominal 4in x 8in)
=
=
Thermal conductivity
=
0
190 x 190 x IOOmm thick (metr ic)
197 x 95mm (nominal 8in x 4in)
Glass block sizes for internal partitions
0.7-1.1 W /m C (0.4 BTU/hr.ft.OF)
120 x 120 x 40mm (nominal 6 x 6 x I
Specific heat capacity
3/4in)
o
=
820-995 J/kg C
and
(0.19 - 0.24 BTU/lb OF)
200 x 200 x 50mm (nominal 8 x 8 x 2in).
Approximate and easily available maximum
The characteristics common to
glass sheet sizes
different glass types are:
I) Float glass
·Variable tensile strength.
Maximum size 3180 x 6000mm ( 125in x
· It is proneto fracture resulting
235in)
from tiny cracks or imperfections.
for thicknesses from 2mm to over 25mm
Cityof Arts and Sciences, Valencia, Spain.Architect: Santiago Calatrava
Oriente Station Lisbon, Portugal Architect:SantiagoCalatrava
·Variable impact resistance. · Non-corrosive.
2) Clear toughened glass
· Non-combustible.
Maximum size 4200 x 2000mm (165in x
· High heat conduction.
80in) for thicknesses from 6mm to 12mm
· Low thermal expansion.
The City of Arts and Sciences inValencia,Spain Architect:Santiago Calatrava
3) Laminated glass Maximum size 3180x4200mm ( 125in x I 65in) for thicknesses from 4.4mm to
Material selection Heat soaked glass is made by re-heat-
9.8mm (31 16in x 3/8in)
ing float glass then cooling it quickly, which
4) Rough castwired glass
putsthe surface of the glass into compres-
Maximum size 3700 x 1840mm
sion and removes impurities such as nickel
( 145in x 72in) for thickness 7mm ( I14in)
sulphide.W hen broken,fully toughened glass
5) Polished wired glass
disintegrates into tiny, comparatively harm-
Maximum size 3300x I830mm
less, pieces. Its strength, measured in terms
( 130in x 72in),thickness 6mm ( I14in)
of impact resistance, is up to five timesthat
6) Body tinted float glass
of float glass.The tougheningprocess can
Maximum size 2540 x 4600mm ( I OOin x
produce minor distortions in the glass, usually
180in) for thicknesses from 6mm to 12mm
caused by roller marks. Heat soaked glass is
City of Arts and Sciences ,Valencia,Spain Architect:Santiago Calatrava
MCH
35
Materials 0 I Glass
Oscar Niemeyer Museum, Curitiba, Brazil. Architect: Oscar Niemeyer
Lyon-Satolas TGVStation, Lyon, France.) Architect: Santiago Calatrava
a partiallytoughened glass for usewhere full
to the rise in temperature to provide a
toughening is not required or as part of a
degree of insulation against radiant heat.
laminated glass construction.
Variable or switchable transmission glass is a new form of treated glass.Though
Laminated glass
Nordpark Cable Railway, Innsbruck .Architect: Zaha Hadid Architects
is made by bonding
two or more sheets of glass together with a
expensive,it aims to reduce internal heat loss
film of plastic in between, called the interlayer.
from inside as well as to reduce solargain. It
The interlayercan be clear or translucent,
is able to change its own thermal and light
and is available in a wide range of colours to
transmission performance by means of an
create effects of colour in the glass that are
electrical signal. In many applications, it turn s
translucent in a way which is different from
from transparent to an opaque whit e when
the screen printing of glass. When broken,
an electric signal is introduced.Applications
laminated glass staystogether in a single
include glazed partitions in office buildings.
piece due to this bondingbetween the lay-
, ""
Glass blocks can
be solid or hollow.
ers. This makes it very useful for glazed roofs
Solid blocks are used as paving for floors.The
and for glazed screens which are set forward
hollow type is used for walls and consists
of glazed facades. However, after the initial
of two half-bricks fused together to give a
impact, laminated glass will eventually fall
smooth appearance on both faces.
away as dangerous fragments of glass, so it is
Glass can be mounted in double- and
required to be replaced as soon as possible,
triple-glazed unitsto provide greaterther-
with the floor areabeneath the broken pan-
mal insulation and sound insulation than is
els typically being secured to avoid the risk
achieved by an equivalent single sheet of
of injury to those below. Combiningseveral
glass. An insulated unit can be a mix of float,
laminates together in one sheetcan make
laminated or other glasses.To improve ther-
anti-vandal and even bullet resistant glass.
mal performance, the air gap between the
Wired glass
is made by sandwiching a
layers can be evacuated to create a vacuum
steel wire mesh between two layers of glass,
or be replaced wit h a low conductivity gas
which are then rolled flat.The wire holdsthe
such asargon.The maximum size of double
glass together for a period of time during a
glazed units is determined by the maximum
fire and so prevents the passage of smoke
sizes of glass types used. However, the size
from one sideto the other.The roughcast
of unit is usually determined by windloading
product can be polished to provide a more
rather than maximum glass sizes.
transparent finish.Wired glasses cannot be toughened and are not regarded as safety products.
Fire resistant glass is formed by glass Metropolitan Cathedral, Brasilia, Brazil. Architect: Oscar Niemeyer
MCH
36
Worl<.ing with the material Float, toughened and laminated glass can be curved. Flatglass is heated and moulded
sandwich panels containing an intumescent
to shape in either one or two directions.
layer. In a fire the layerof gel, or salts, reacts
Floatglass can be cut,drilled,screwed and
Oscar Niemeyer Museum, Curitiba, Brazil. Architect: Oscar Niemeyer
glued. It can also be bolted using proprietary
layer of metal which allows maximum day-
systems. Toughened glass cannot be cut,
light and short-wave heat t o ent er the build-
drilled or surface worked after manufacture
ing but reduces heat loss by reflecting long
but laminated glass can be drilled wit h spe-
wave radiation trying to escape at night.The
cialist equipment.
coating is hardly visible.
Surface and body treatments
Recycl ing
Float,toughened and laminated glass can
Oscar Niemeyer Museum, Curitiba, Brazil. Architect: Oscar Niemeyer
Glass is one of the easiest mat erials to
be furt her treated to allow varying levels
recycle and is economically viable. Enormous
of light transmission and thermal insulation.
energy savings in glass manufacture can be
Sometimesthis is done during the manufac-
made by recycling the material.
turing process.These treatments are body t inting, screen-printing, sand blasting and acid etching, coatings, including low-E and fritti ng, and curving. Body tinted glass is produced by small additions of metal oxidest o the glass, reduc-
BCE Place,Allen Lam bert Galleria and Heritage Square,Toronto, Canada Architect: Santiago Calatrava
ing solar gain.A limited range of tints is available,including shadesof green, grey, bronze and blue. Fritted glass is made by printing ceramic designs onto float glass, which is then toughened.This process involves fusing coloured frit (powdered glass), through a stencil onto the surface of the glass, providing a permanent durable finish.This treatment can be used to help reduce solar gain. Surface printing with a high level of detail can be achieved by screen-printed dots, lines or meshes. Sand blasting and acid etching are surface treatment s which produce a uniform, matt translucent finish.The microscopically pitted surface has a tendency to retain dirt and grease, making it difficult t o clean. A low-emissivity coating (low-E) is applied to glass to improve its thermal insulation.The coating is a microscopically thin
Nordpark Cable Railway. lnnsbruck.Architect Zaha HadidArchitects
MCH
37
Materials 0 I Tectonics in concrete
Francois Hennebique
Claude Nicolas Ledoux:theVillede Chaux,France
Concrete had been used for over 2000
used.There is no visible detailing;the mono-
years before advances were made during
lithic expression of the building forms seem
the 19thcentury with the development
to relate more to military installations of the
of reinforced concrete, a techniquethat
time than to the language of public buildings.
involved incorporating metal rods to com-
The window openings are small and seem
pensate for the inherent weakness of the
only to emphasisethe visually massive qual-
material in tension. Fran<;ois Hennebique
ity of the walls.W hile the material used for
constructed in 1892 what is thought to be
the buildings is not clear from the drawings,
the first building with a reinforced concrete
stone-faced loadbearing masonry would
frame. Ernest Ransome patented a similar
probably have been used as the material
system in the US in 1895. By the beginning
system of the time. However, the monolithic
of the 20th century, in Europe and in North
forms are very much in tune wit h concrete;
America, iron rods and wireswere being
large flat areas with no registration of joints
used as reinforcement in patented floor
or traces of the waythe building would be
systems and structural frames. Modern rein-
constructed. It looks as if no evidence of the
forced concrete is essentially a development
construction method should be visible in
of these systems.
order not to detract from the architectural
An essential quality of concrete is that
Unite d'Habitation,Marseille,France. Architect: Le Corbusier
De laWarr Pavilion,Bexhill. Architect:Erich Mendelsohn and Serge Chermayeff,
MCH
38
messages in t he form of the building con-
it is a moulded material, capable of creating
cerned wit h expressing the intended use of
large-scale monolithic forms without joints in
the building.Another drawing shows a design
the material. This essential quality was hinted
for a cemetery with a shell structure in the
at much earlier, the work of Claude Nicolas
centre of an unspecified construction.This
Ledoux in the late 18th century demon-
could have been achieved 150years later
strat es an intent in architectural expression
in concrete, as seen in the work of Eero
through abstracted forms that represent
Saarinen and Santiago Calatrava. Ledoux
'functions' of the building or the functions of
built on examples of his vision at the Ville de
the principal uses of the building. His book
Chaux using primary geometric forms with
Archit ecture consideree sous Ie rapport
columns and rusticated stonework.The idea
de I'art, des moeurs et de la legislation sets
of the architect as giving visible form to the
out a vision of the archit ect as providing a
function of society in monolithic architectural
visible structure of a society where status
form was later taken up by Le Corbusier,
is accorded t o 'functions' in society rather
as seen in his design for the chapel at Ron-
than power or wealth.The Water Inspector's
champ.
House expresses the function of its occupier,
The evolution of concrete as a building
with river water passing through the building.
material was the result of a 'rediscovery' of
The form shown in t he drawings is mono-
the material primarily as a mortar in engi-
lithic, wit h little expression of the material
neering projects, but to its eventual use as
The Centennial Hall,W roclaw,Poland,Architect: Max Berg
a structural material used wit h first arches
building has a roof that begins to exploit
and then for floors, columns and then asa
the sculpt ural possibilities of concrete:the
full structural frame.Joseph Monier's system
architect was influenced by, among others,
of using steel reinforcement in a syst emat ic
the unbuilt projects of l.edoux.The base
manner; first seen in 1867,was a develop-
structure that form s part of the ring beam
ment of earlier mixes of metal and concrete
for the dome above is curved in three
that themselves probably evolved from the
dimensions, and shows the possibilities of
metal rods and brackets used as tension
construction which were followed up in
members in timb er and masonr y structures
later concrete shell structures,The dome
that go back to at least the reinforced metal
is formed wit h inclined sculpt ural ribs on
hammer beam roof of the Palace of W est-
which are set vert ical members, which in
minster Hall in London, built in the late 14th
turn support horizontal decks that provide
century Francois Hennebique's reinforced
both horizontal ribs to stiffen the inclined
concrete system developed t his concept into
members aswell as serving as ring beams
full reinforced concrete wit h a system pat-
for lateral stability This structure seems to
ented in 1892,The nature of reinforced con-
support vertical windows to wit hstand the
crete is such that its method of construction
rain and snow of the harsh winters,This
is not visible, except for t he marks left by the
structure begins t o exploit t he possibilities
formwork, which can be either expressed
of structure of enclosing spaces wit hout
or concealed, but the formwork is removed,
the rectilinear imperatives of masonr y and
wit h the boards or sheets being used only
timb er construction where walls, structure
once or twice before being discarded after
and enclosure are made from concrete as a
use, Hennebique's system, now so familiar t o
single material.A st eel frame wo uld require
us, uses a web of steel reinforcement which
infill of th e lower arched structure and of the
is never visible but which has a high degree
roof decks circling the dome in a different
of elaboration and visual character prior
material, which results in a loss of clarity of
t o it being concealed wit hin concrete. The
the architectural idea of sculpting structural
benefit of concrete as having a high level of
forms, ideas which would later be developed
fire prot ection has added to the popularity
by Sant iago Calatrava
of this material. However; concrete was still
The Pantheon, Rome, Italy.
In about the same year asthe Centennial
used as a substit ut e for masonry and timb er
Hall in W roclaw was the Dom-ino concept
construction, wit h its rectilinear forms.
of structure by Le Corbusier.The idea is
An example of the use of concrete as a
The Centennial Hall,Wroclaw, Poland,Architect: Max Berg
essentially a reinforced concrete structure
material in its own right, rather than imitat -
of fiat slab supported by columns, a method
ing the language of an earlier t echnology is
th at was not in general use until th e 1990s
the Centennial Hall inW roclaw, designed
when reinforcing methods made economic
by Max Berg and completed in 191 3.The
th e junction of slab and column, Unlike Le
The Nit er6i Contemporary Art Museum, Brazil. Architect: Oscar Niemeyer
MCH
39
Materials 0 I Concrete
Notre Dame du Haut Ronchamp Chapel France. Archit ect: Le Corbusier
Xochimilco Restaurant. Mexico City. Architect Felix Candela
Corbusier's later celebrated concrete struc-
Copan Building" Sao Paulo, Brazil. Architect: OscarNiemeyer
ture of the chapel at Ronchamp, the external
internal floors, staircases and partition walls,
wallsare formed from another material,
with internal fittings of information desks
which would typically be a combination
and counters being designed as miniature
of concrete and glass.The diagram of the
building forms in their own right.The build-
Dom-ino structure is clear.but the bands of
ing could have been formed using inflatable
glazing, running either vertically or horizon-
formwork; its intersecting vaults would have
tally. with an infill of rendered blockwork are
lent themselves to inflatable structures. In
independent of the system. Le Corbusier's
many ways the constructed building is itself
idea of a structural grid with constructed
almost a virtual form of an inflatable build-
objects set within it and which contrast wit h
ing, the concrete describingthe forms which
the grid, seems to connect very strongly with
could be achieved by plastics and fabrics, and
the Dam-ino concept.The gesture and grid
can be seen as a 'frozen' idea of invention in
contrast of forms is still visible at Ronchamp
building construction yet to come.
in three of the external walls with an overal l form described by the floor plane. The Guggenheim Museum in New York.
MC H
40
possibilities of concrete are extended to
The work of Santiago Calatrava takes a different turn to that of Eero Saarinen. W here theTWA Terminal uses a series of
completed in 1959 and designed by Frank
intersecting vaults that are formed as con-
Lloyd Wright, exploits the cast nature of
crete shells, projects such as the Science
concrete t o create a single spatial form of
Park at Valencia are formed as framed and
external walls and floors and follows in the
arched structures from a series of sculpted
tradition of Ledoux of highly modelled form
ribs. Rather than the vaulted aesthetic of a
that creates a clearvisual impression of the
single material system of TWA, theValencia
idea without the visual language of a vis-
building uses glass as an enclosing material
ible building assembly.An example of a roof
which avoids the need to add layers to an
based structure where the sculptural abili-
equivalent concrete shell.The use of bolt
ties of concrete are used is the Xo chimilco
fixed glazing with steel supporti ng ribs linked
Restaurant in Mexico City by Felix Candela.
back to the concrete ribbed structure cre-
This form, based on hyperbolic parabalaids,
ates an approach of mixing materials where
was formed using straight lengths of timber
the concrete frame and the glass enclo sure
board for the formwork, allowing a complex
are part of a single idea of using animal
form to be created with very simple form-
skeletons as a metaphor for the design. Cala-
work that required no specialist carpentry
trava's interest in anthropology led him to
skills, since the formwork was not required
consider the relationship of bone and muscle
to be curved.The concept of the concrete
to use two materials in an interdependent
shell was developed in the TWA Terminal by
way rather than the more straightforward
Eero Saarinen. In this building the sculptural
'layered' approach of traditional construction.
The Guggenheim Museum,NewYork, USA. Architect: Frank Lloyd Wright
Xochimilco Restaurant, Mexico Cit y. Architect:Felix Candela
This approach can also be seen in Calatrava's
Concrete wit h dense aggregate:
bridge structures,where steel is used asa
2240 to 2400 kg/m3 (140 to 150 Ib/ft3)
material separate from the reinforcement
Conc rete with lightweight aggregat e:
only within the concrete as reinforcement.
320 to 2000 kg/m3 (20 to 125 Ib/ft3) De sign strength = 35 N/mm2
In the bridges,the tension qualities of steel
Young's Modul us:
linking concrete elements rather than being
reinforcement are brought out of the con-
= 1.5 x 104 to 3.0 x 104 N/mm2
crete as steel components in their own right.
(3.1 x 108 to 6.2 x 108 Ibf/ft 2)
Of course,the concret e is still reinforced,
Coefficient of the rm al exp ansion
=12.0 x
other functions rather than beingonly buried
10-6 K- I to 7.0 x I 0-6 K- I (6.7 x 10-6 to 3.9 x 10- 6 F-I)
in the concrete. Calatrava's interest in animal
reducing wit h age.
skeleto ns and the lessons that can be drawn
The rma l cond uctivit y:
from them for use in building design can be
Concrete w ith dense aggregate:
but steel is also used as a component with
o
seen in his proposal for the Cathedral in
= 1.0 W /m C
New York where the sculptural possibi lities
(0.58 BTU/hr.ft.OF)
of concret e,together with t heir ability to be
Concrete wit h lightweight aggregat e:
made into large scale components, is clearly
0.5 W /m C
visible in the design.These ideas have found
(0.29 BTU/h r.ft.0F) • 0 Specific heat =840 J/kg C (0.20 BTU/lb OF)
their way into Calatrava's single designs for glazed roofs such as the MilwaukeeArt
o
=
The Guggenheim Museum.NewYork, USA. Architect:FrankLloyd Wright
Museum.The Milwaukee additions form an extension of an earlier project by Eero
Concrete has the following
Saarinen.Where Saarinen's project is essen-
propert ies:
tially rectilinear,with identical sculptural ele-
· Easily moulded.
ments used in bays to create what is essen-
· High strength in compression.
tially an extruded structure,Calatrava uses a
· High acoustic insulat ion for both airborne
similar discipline of geometry to create more
and structure-borne sound.
complex forms, but with his characteristic
· High fire resistance, but appropriate cover
interest in bringing daylight from roof lights
to steel reinforcement is needed.
and creating varying effects of daylight.
· Most shrinkage of the material occurs, as creep, during the first year after casting.
Propert ies and data
· Moisture movement occurs but is less significant than ti mber.
The main propertie s of concrete are as fol-
· Slightly permeable to wat er.
lows:
· It will not set properly if the air
Density:
t emperature approaches freezing point. If
TWATerminal,JFKAirport, NewYork Architect: Eero Saarinen MCH
41
Materials 0 I Concrete
Stadelhofen Station,Zurich, Switzerland. Architect:Santiago Calatrava
Milwaukee Museum ofArt. Architect: Santiago Calatrava
the air temperature istoo high, it will set too quickly, causing cracking.
Concrete shrinks as it dries, and can take more than a year to reach its final size, though it continues to shrink indefinitely by
Material selection
Milwaukee Museum of Art, Architect: Santiago Calatrava
Concrete is a dense material, composed
erable in the period immediately following
of cement and aggregate mixed with water.
the pouring, but slows down by the end of
It sets to form a hard, brittle material, strong
the first year. After approximately 28 days,
in compression but weak in tension. Portland
concrete approaches its design strength. It is
cement is the most widely used binding
important that the mixture should not dry
agent for concrete and consists of lime and
out too quickly to enablethe chemical reac-
clay mixed together at high temperature,
tions between the constituents to take place.
which is then crushed to form a fine powder.
Controlling the drying process is known as
The type and relative proportions of
'curing'. Having dried out, concrete subse-
cement and aggregate will vary according to
quently absorbs wate r. but any expansion is
use and desired appearance.The mix should
always much less than the original shrinkage
make economic use of the cement.Varying
during the curing process. Plasticisers can be
the composition of the constituents produc-
used to vary the rate of drying,which reduc-
es different strengths of concrete.The most important factors are the wate r to cement
es construction time. Plasticisers also increase the workability of the wet concrete.
ratio and the proportion of cement to aggre-
crete are combined to take advantage of the
aggregate:coarse aggregate).The amount of
compressive strength of concrete and the
water used in the mix affects both workabil-
tensile strength of the steel used.Two types
ity and strength. Less water increases strength
are used; mild steel reinforcement is used
but reducesthe workability, making it more
to form complex elements and has a yieldstrength of around 250N/mm2, and high
reinforcement when it is being poured in
MCH
42
In reinforced concrete, steel and con-
gate.A typical mix isthe I:2:4 (cement: fine
difficult for the concrete to flow around the
Milwaukee Museum of Art. Architect: Santiago Calatrava
tiny amounts.The rate of shrinkage is consid-
place.The reduced workability is improved
yield reinforcement is used elsewhere with a yield-strength of around 460N/mm2.As
by using additives, such as plasticisers,to the
the concrete sets it shrinks, gripping the steel
mix.The coarse aggregates, consisting of small
bars thus producing a monolithic structural
stones,form most of the mass,while spaces between these stones are fill ed by fine aggre-
material for use as frames,walls and floors. These can be cast-in-place at the site, or off-
gate and cement which bind the mixture
site as precast elements.W ith either method,
together. It is importantwhen pouring con-
the cost of formwork, or mould, can rep-
crete,that the mixture is properly vibrated
resent up to halfof the cost, and therefore
to ensure that the coarse aggregate is fully
the efficient use and re-use of formwork is
surrounded by the finer material.
essential.
PhaenoCentre,Wolfsburg,Germany. Architect:Zaha Hadid Architects.
Phaeno Centre,Wolfsburg, Germany. Architect:Zaha Hadid Architects.
Cast-in-place reinforced concrete is
transport costs.To be economic,and com-
usually delivered to site ready mixed and is
parable in cost with cast-in-place construc-
poured either by pumping or by crane buck-
tion,the number of different components
et. Cast-in-place reinforced concrete is made
should be kept to a minimum, becausefewer
by setting steel reinforcing rods, often in the
moulds, prototypes and trial panels would
form of a cage, between formwork, made
be used. On larger projects, it may be cost-
from plywood, steel or timber boards.Wet
effective to manufacture precast components
concrete is poured and compacted.The rein-
on site in a temporary facility.This avoids the
forcement must have an appropriate cover of
need to transport components,though such
concrete to protect it in the event of fire. The
conditions may not be ideal for high quality
cover also protects the steel from corrosion.
work. Precast concrete systems are manufac-
A series of bolts holds the sides of the formwork apart and shoring on the outside
tured as proprietary systems for both structural frames and wall cladding panels.There is
of the formwork supports the weight of the
a significant move towards re-using the form-
wet concrete.The formwork is removed, or
work from one application to the next.
struck, after 3 to 4 days and the holes left
Components are cast in moulds which
behind are filled with grout, which is a mix-
are made from glass reinforced polyester,
ture of cement and water. Since the holes
steel or concrete.Accurate manufacture is
remain very apparent, they are arranged at
difficult with plywood and timber due to the
regular centres in order to enhance their
thermal movement of these materials, mak-
appearance. The technique of manufacturing precast
ing the mould sizes unreliable. Panels are cast either face-up or face-down.In face-down
concrete,developed in the I950s, hasthe
casting the inside surface of the mould forms
advantage of a reduced construction time,as
the component finish. In face-up casting the
no curing, and much reduced formwork, is
surface of the mould forms the backof the
needed on site. Concrete is cast in moulds in
component so that structural ribs can be
a factory, and then delivered to site. Precast
formed, leaving the panel face fiat. An alterna-
techniques have two main advantages over
tive method,which avoids complex form-
cast-in-place construction.The first is that
work, is tilt up construction.This is a partially
quality can be easierto control in a work-
precast method where a wall is cast fiat on
shop,and the second isthat precast elements
the ground at the site, directly adjacent to
can be assembled rapidly on site. Cast-in-
the floor slab. Once it has cured sufficiently, it
place concrete needs time to gain strength
isthen lifted up intothe vertical position and
before it can support another element and
bolted directly in place.
this slows down construction dramatically. Precast concrete is usually more expensive than cast-in-place due to additional
Opera House, Valencia,Spain. Architect:Santiago Calatrava.
Prestressed concrete is a precasting techniquethat istypically used in floor structures. Itallows increased clearspans to be
Concert Hall of Santa Cruzde Tenerife.Architect: Santiago Calatrava.
MCH
43
Materials 0 I Concrete Precast floor components, from timber-based mould to floor panel, beam and panels being installed
used with thinner slabs resulting in lighter
to be prestressed, or where the construction
structures.The reduced cracking and reduced
method dictates that they are to be built on
deflections in this technique are a distinct
site,the technique of post-tensioning can
advantage over normal reinforced concrete.
provide a similar method of reducing the
In common with other precasting techniques,
depth of beams, decks or related assem-
this rapid construction method allows con-
blies such as masonryarches. Although this
struction times to be reduced.
technique is used mainly in bridge-building,
In prestressing, high strength steel wires, rods or cables are passed through a small
components, such as frames and floors,to
diameter tube set into a precast component,
use prestressing techniques with a site-based
typically a beam or a tee-section used as a
construction method.Post tensioning is more
structural deck.The wires, set in the bottom
suited to large assemblies such as arches and
half of the beam, are tensioned at the ends,
long-span floor decks than to smaller-scale
resulting in the beam or tee arching up in a
assemblies where the time needed on siteto
slight camber.The tubes are then filled with
effectthe tensioning would slow down the
grout.When the prestressed component is
speed of construction.
set in place, the imposed loads flatten the
toppings in profiled steel/concrete composite
rienced by the component.
construction. It is also used for non-loadbearing components such as precast wall panels.
beam is loaded, compression is created in
It is not used for high strength applications,
the top half of the beam andtension in the
but is suitable for most structural applications
bottom part.The compressive stresses in
where weight is an important consideration.
the concrete created by the tension wires
The material is typically made from crushed
must be overcome before the beam bends.
pumice or clinker; giving it better properties
However; when a prestressed beam or simi-
of heat and sound insulation than cladding
lar component is loaded, the concrete is in
panels made from other materials.
compression throughout its depth,allowing
Ferro-cement is a concrete-based mate-
it to be shallower in depth than a reinforced
rial which is typically used to makeyacht
concrete equivalent. Prestressed concrete is
hulls.This material is beginning to be used
more suitable for large spans than ordinary
as a structural material in buildings, and is
reinforced concrete because components
suited to complex shapes with a high qual-
can be shallower and as a consequence be
ity smooth finish.A recent example isthe
lighter; reducing the dead load. Prestressing
curved roof trusses of the Menil Museum in
increases resistance to shear forces com-
Houston,Texas, USA.Ferro-cement consists
pared to a reinforced concrete beam, making
of a cement mortar-based mix with a high
it possible to achieve a more slendersection
degree of steel reinforcement. It has good
than using cast-in-place techniques.
tensilestrength in thin sections. Complex
Where these components are too large
44
Lightweight concrete is used primarily for
pre-camberand reducethe deflection expeWhen an ordinary reinforced concrete
MCH
post tensioning allows individual large-scale
shapes can be formed by applying the wet
mix onto a steel mesh by hand without the need for formwork.
smooth screed. The fine aggregate and cement determine the colour of the concrete . Changing
Working with the material Concrete is compacted by vibration
the attributes of the fine aggregate has a dramatic effect on the appearance of the
when poured in order to remove air voids in
concrete, whereas large aggregate has little
the mix and to achieve an even distribution
effect unless retardants are used and the
of the material inthe formwork.Too litt le
large aggregate is exposed. Colour additives
compaction of the wet material can result in
can also be added to the mix. Unfortu-
air pockets being leftinthe mix,weakening
nately, slightvariations in the proportions
the concrete.Too much compaction brings
of additives have a dramatic impacton the
the fine aggregate to the surface, making the
appearance of the concrete, making it hard
surface crumbly, and causing surface staining.
to achieve consistent coloration between
A vibrating instrument, inserted into the wet
batches.
concrete , is used to ensure an even consist-
Paint provides a thin decorative layer; but
ency.The reinforcement is given an adequate
is prone to flaking and requires re-coating
cover of concrete to protect it in the event
at regular intervals.Colour stains are an
of fire .The cover also reduces t he possibility
alternat ive as they are absorbed by t he top
of water reaching the steel which can cause
surface of the concrete forming a permanent
it to rust. In the manufacture of precast com-
coloured fi nish. Sand blasting and acid etch-
ponents the mould istypically compacted,
ing, processes more commonly associated
either by placing it on a vibrating table or by
with glass,can also be used. Bush hammering
applying a surface mounted vibrator.
the mater ial exposes the large aggregate and provides a rough texture to the surface.
Fi nishes Concrete adopts the texture of the
Conversely, polishing provides a smooth shiny surface. However; both of these surface treat-
fonmwork. Steel formwork leaves a smooth
ments are very labour intensive. Unpolished
appearance while softwood boards leave an
concrete has a dusty surface and it may be
imprint rangi ng from fairly smooth plywood
appropriate to seal the surface.
to rougher fin ishes of planks. Boarded formwork produces a pattern of joints across the concrete face. Othe r finishes include tamping,where a board is moved in a tapping
Recycl ing Concrete can be recycled by crushing the mater ial and using it as an aggregate in
action across the surface of the concrete to
new concrete. Although the use of recycled
form a directional text ure;t rowell ing,where
concrete is new,it has been successfully used
concrete is smoothed wit h a hand tool;
in new reinforced concrete structures.
and power floating,where a poured slab is smoothed with a machine to provide a fi nish that avoids the need for an additional layer of
MCH
45
Materials 0 I Tectonics in masonry
Corpus Christi, Cambridge, UK.
StJohn's College,Cambridge,UK,
The pre-industrial use of masonry was as a
WestminsterAbbey. London, UK.
loadbearing mat erial that integrat ed struc-
built examples across England,The college
tu re and facade int o a single construction
buildings of the universities of Oxfo rd and
that was capable of taking up complex geo-
Cambridge contained Gothic elements of
metric forms, such as those used in castles
construction through the Renaissance, with
and lat er in medieval houses across Europe.
a gradual re-intro duction of Gothic language
In addition to their ability to form complex
emerging in folliesto English country houses
shapes in plan, masonry has the ability t o
built during the 17th and 18thcenturies.The
corbel outwards or inwards from the verti-
Gothic revival of the 19thcentury, which
cal plane of the wall through their height to
associated the architecture and its associated
create a more complex section than that of
forms of construction with renewed spiritual
verti cally set walls,A 20th century example
values, introd ucedthe use of iron into forms
of this principle was used in Ant onio Gaudi's
previously constructed entirely in masonry.
work on the Sagrada Familia in Barcelona.
Buildings such as the Oxford Museum in
This use was in parallel to the emerging use
England combined medieval methods of
of cavity walls at the time for houses built in
loadbearing masonry construction and their
England, In cavity wall construction, the loadbear-
ent loadbearing structures gives a structural
and linked structurally to form a diaphragm
continuity between building element s and
wall: a construction t hat uses less material to
also between buildingforms, as seen in the
achieve the same purpose.A disadvantage
city centre of Oxford, where there is a con-
is the need to extend floor plates through
tinuity of constructional language from door
in order to make the wall perform structur-
to wall t o building to city block t o street.
46
The move from masonry used in load-
thermal bridge that can cause high levels of
bearing structures to its usealmost entirely
heat loss (or heat gain in hot climates) and
as non-Ioadbearing cladding came in the
associated condensation risk Consequently,
early 20th Century with the introduction of
the outer leaf of the cavity wall became iso-
steel and concrete frames, initially int ended
lated from the construction behind except
for taller buildings but soon becoming the
at fixing or restraining point s, as is the case
standard method of construction for all but
wit h stone cladding.The resultant use of
small residential buildings, with the out er
cavity walls as an outer prot ective screen
walls becoming non-loadbearing and roofs
has robbed it of any real significance in the
using the full extent of the structural frame
construction.
for support .
The use of masonry in Gothic cathe-
MCH
re-interpretation as glazed vaults of iron ribs into a single building.The ability to mix differ-
ing wall is divided into two separat e halves,
ally as a diaphragm wall, which result s in a
O riel College, Oxford, UK
continued on, almost uninterrupted, in
drals as loadbearing structure and enclosure
A trend in the past 30 years has been the introductio n of thermal insulation int o
St George's Chapel,Windsor Castle,Windsor, UK.
Bristol Cathedral, Bristol, UK
masonryconstruction as well as a layer of
benefits of thermal mass to be used within
weatherproofing when a cavity is introduced.
the building as well as a weathering surface
This has resulted in much masonryconstruc-
on the outside along wit h the possibility of
tion becoming an outer rainscreen, either
the masonry being exposed within the build-
as cladding panels of stone, or as the outer
ing.
skin of a cavity wall. In some cases, loadbear-
The use of loadbearing masonry has
ing walls have had the insulation set in the
found limited applications due to the per-
centre of the wall, wit h the two halves of
ceived disadvantages of setting thermal insu-
the construction linked by stainless steel ties
lation on the inside face of the wall, reducing
to provide structural continuity through the
its thermal mass. Consequently, masonry is
full thickness of the loadbearing wall. The
used mainly as cladding to a backing wall
Glyndebourne Opera House in England,
which istypically insulated on its outside
designed by Michael Hopkins and completed
face in order to benefit from the thermal
in 1994, has no thermal insulation but is fully
mass of the wall within the building, with
loadbearing. Loadbearing brickwork is used
the additional advantage of beingable to fix
to form the external wall and gallery for the
interior items such as shelvingto the inside
opera houseauditorium. Lime-based mortar
face of the wall.A disadvantage of the useof
was used to avoid the cement-based mortar
masonry is its lackof relationship with the
associated with high strength, but the need
real building immediately behind the outer
for vertical movement joints at typically 7.5
skin.As an outer veneer, its relationship to
metre centres.These joints have the effect
the structure and enclosure of the building is
of dividingan external wall into separate
largely a matter of individual aesthetic choice.
bays, making a single monolithic wall almost
Since cladding panels can be large in size, up
impossible to achieve. Because of the
to around 700mm x 1400mm for granites
loadbearing strength of lime mortar being
and stronger sandstones,the relationship
approximately halfthat of cement-based
wit h historical context is severely limited.
mortar that would have been required for
Wells Cathedral, Wells, UK
The contemporary useof loadbearing
this project, the walls were thicker but,at
construction provides an opportunity to
one and a half bricks thick,are no wider
provide thermal mass in facades as well as
than an equivalent cavity wall,but wit h piers
in that provided by adjacent fioor construc-
which are two bricks thick.The avoidance
tion.When informed by structural require-
of movement joints assured the monolithic
ments linked to either a historical typological
appearance and structural efficiency of this
model,or spatial sequence,the material
structure.
system suggests ways of enclosing space that
In other applications of loadbearing
creates an architectural expression specific
masonry, the positioning of the thermal
to the requirements of the building. In the
insulation in the centre of the wall allows the
case of masonry, which forms the historic
Bristol Cathedral,Bristol, UK
MCH
47
Materials 0 I Masonry
Magdalen College,Oxford, UK,
Trinity College,Cambridge, UK,
fabric of Englishtowns and cities,This use of
of buttressing from cat hedrals have been
masonry would provide a continuity with
used at a more modest scale for secular use.
the past but would be able to have a more
Market Cross,Chichester, UK
Loadbearing masonry has the ability to
dynamic and progressive relationship wit h
make complex shapes for structures and
historic fabric as is achieved in the buildings
enclosures, but the position of thermal insu-
of Antonio Gaudi in Barcelona. Loadbearing
lation within the construction is difficultto
brickwork was used in larger scale buildings
achieve. An equivalent framed structure in
by Louis Kahn in the Indian Institute of Man-
reinforced concrete or steel, with masonry
agement ofl962, and where the brickwork
cladding fixed to it, istypically much easier to
is used as 'cladding' Kahn expressed its sense
form but the masonry skin is reduced to an
of separation without reducing its quality of
essentially decorative role.A future direction
visual massiveness. Kahn in part achieved this
for masonry may be as a mixture of precast
by putting'buildings within buildings' which
concrete masonry-like forms that can be
might be a way forward for loadbearing
both structural and integrat e thermal insula-
masonry construction by creating buffer
tion within the depth of the material. If pre-
zones in buildings which do not require ther-
cast concrete techniques for making vert i-
mal insulation, such as winter gardens, circu-
cally stacked units are made at a smaller size
lation areas or outer spacesthat provide a
than is usually the case,then t hey could be
thermal buffer.
used to make loadbearing structures from
Mat erial systems based on masonry con-
these small units.This would bring the histor-
struction often work well with those in tim-
ic advantages of masonry construction back
ber,as in English medieval guildhalls and inns.
into mainstream construction. Concrete can
Lightweight timber structures are often set
be formed into small masonry units that can
on top of masonry structures, while more
be lifted with modest equipment.The ability
ambitious structures such as the George Inn
of masonry to corbel in and out of verti cal
at Glastonbury seem to imitate the framing
plane without the need for formwor k is a
of timber in stone - the refinement of t im-
characteristic that has had limited use in the
ber finding its way into loadbearing masonry
design of external walls, but is experiencing
wall design. In some buildings such as the
a modest revival with brick walls of complex
Guildhall at Cirencester and college buildings
geometry or curved surface.
at Oxford and Cambridge, stone is used for
George Hotel and Pilgrim's Inn Glastonbury. UK
MCH
48
window mullions, with glass being set into
Material selection
a narrow lead frame that avoids the useof
The principles of using materials are com-
timber altogether.The inventio n in masonry
mon t o stone, brick and block.The relation-
at thist ime can be seen in buildings such
ship between the masonry unit and the
as the Market Cross at Chichester and the
mortar is of particular importance.
Poultry Cross at Salisbury. where techniques
Mortars for loadbearing masonry and
New College Chapel, Oxford, UK.
Trinity College,Cambridge,UK.
cladding panels usethe same materials and
the type of stone and its intended use.As
follow the same principles in stone, brick
a result the mortar is the best compromise
and concret e blockwork.The compatibility of
between load,structural movement,water
masonry and mortar is an essential factor.It
permeability and preferred colour. Mortar
is usual to use the weakest mortar that will
joints can also be reinforced with steel mesh.
adequately sustain the load, because increasing strength can result in t oo much rigidity which would cause cracking. The strength is varied by altering the
Recycl ing Natural stone can be recycled if the mortar is soft enough to be removed, par-
proportions of the binders cement and lime.
ticularly if a lime putty mortar has been used.
Stronger mixes have more cement, while
Otherwise, stone and brick are used for
lime provides flexibility which allows the
structural fill.
brickwork to move without cracking. Different mixes of mortar are used depending on whether the masonry is used as cladding or as loadbearing masonry. Mortar mixes have to achieve a balance between strength and
Bristol Cathedral,Bristol,UK
flexibility.The comparatively low permeability of lime gives great er resistance to rain penetration. Lime also makes a mortar lighter in colour than a cement-based mix. Mortar mixes are a balance between the needs of loads, structural movement, water permeability and preferred colour. In terms of appearance, it must be noted that the mortar accounts for between I0 and 20 per cent of t he masonry, and conse-
Divinity School.Oxford,UK
quently makes an import ant contribution to the colour ofthe surface.The colour of the mortar can be controlled by using pigment additives. In addit ion,the way that the joint is made has an important effect on the flatness or amount of shadow perceived. In stonework,crushed stone is often added to the mortar mix as fines instead of sand so that the joints match the stone as closely as possible.The mix depends on
ChristCollege,Oxford,UK
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49
Materials 0 I Concrete block
Assembly Hall at University of Illinois,Champaign, Illinios, USA.Architect: Max Abramovitz
Palais deJustice,Chandiganh,India.Architect:Le Corbusier
Masonry block Masonry blocks are made from concrete in a range of sizes and strengths. Some
blocks. are made as a facing material, it is more usual to conceal blocks, or face them with another material such as render.
types are designed to withstand large compressive forces and are therefore made with
Ross Humanitiesand Social Sciences Building,York University, Toronto,Canada
Working with the material
a high-density concrete.They can withstand forces of up to around 20N/mm2 (4.2 x
fixings in the form of brackets and dowels
105 Ibf/ft 2). Other types are designed to
are used for walls where the blockwork
provide limited amounts of thermal insula-
does not provide sufficient stability.These
tion and are made with aerated concrete
fixings are used extensively in blockwork
Block can be easily cut and drilled. Metal
or with insulation bonded to one side. Most
cladding which is support ed by a structural
types of block are manufactured to course
frame.
with brick but the size of the block will depend on its weight. since the block must
SIZES
be lifted by hand. Variousthicknesses of
Common metric block size:
block are available for different applications.
Length 390mm x Height 190mm ( 15 5/8in x 7 5/8in)
Material Types Types used are dense aggregate blocks,
Overall dimensions (Length 400mm x Height 200mm with
light aggregate blocks and aerated blocks.
IOmm joint) ( 16in x 8in with 3/8in joint)
Blocks with dense aggregates are more com-
A range of thicknesses is made.
monly used for loadbearing walls.Those with
Common UK block size to course with UK
lightweight aggregates and aerated mixes
brickwork:
are used for non-Ioadbearing walls and
Length 440mm x Height 215mm (Length
partitions.All thesetypes are made in solid.
450mm x Height 225mm with IOmm joint)
cellular and hollow form. Cellulartypes allow
Lyon-SatolasTGV Station, Lyon, France Architect: Santiago Calatrava MCH
50
the voids to be filled with concrete and rein-
Blockwork has the following general proper-
forcement to improve structural perform-
ties:
ance.The main advantage of block is its low
· Heavy.
cost and the speed with which walls can be
· High compressive strength.
built. Although some blocks, called fairfaced
· Very low tensile strength.
Sainte Mariede laTourette, Lyon, France.Architect: Le Corbusier
· High resistance to weathering · High impact resistance. · High fire resistance. · Susceptible to thermal and moisture movement. · Not waterproof. · Low seismic resistance. · Easy to cutto size.
Properties and data The main properties of masonry blockwork are as follows: Density: Dense aggregates = Over 1500 kg/m3 (94 Ib/ft3) Lightweight aggregates = I000 to 1500 kg/m3 (62 to 94 Ib/ft3) Aerated = 500 to 1500 kg/m3 (3 I to 94 Ib/ft3) Compressive strength Dense concrete blockwork = ION/mm2 to 20 kN/mm 2 (209 x 103 to 418 x 103 Ibf/ft2) Aerated concrete blockwork = 3.5NI mm2 to 7.0 N/mm2 (73 x I03 to 146 x I03 Ibf/ft2) Young's Modulus: Dense concrete blockwork = 5.0N/mm 2 to 25.0 kN/mm2 (1 .\ x 105 to 5.2 x 105 Ibf/ft2) Aerated concrete blockwork = 2.0NI
Villaverde Housing Project, Madrid, Spain.Architect; David Chipperiield Architects
mm2 to 8.0 kN/mm2 (4.2 x 104 to 1.8 x 105 Ibf/ft2) Coefficient ofThermal Expansion: Dense concrete blockwork = 6 x I0-6 to I2 x I0-6 K- I (3.4 x 10- 6 to 6.8 x 10- 6 OF-I) at 5% moisture content Aerated concrete blockwork = 8 x I0-6 K-I (4.5 x 10-6 OF-I) at 5% moisture content Thermal conductivity: Dense concrete blockwork = 1.2 WI 0 m C (0.69 BTU/hr.ft.0F) Aerated concrete blockwork= OJ WI 0 m C (0.17 BTU/hr.ft.OF) o Specific heat capacity= 840 J/kg C (0.2 BTU/lb OF) for dense concrete blockwork
Institute of Education + Law, London, UK. Architect: Sir Denys Lasdun + Partners
Ennis-Brown House, LosAngeles, California,USA Architect: Frank LloydW right
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51
Materials 0 I Stone
Parc Guell, Barcelona, Spain.Architect:Antonio Gaudi Sagrada Familia, Barcelona, Spain.Architect:Antonio Gaudi
Production process of raw material
. Low seismic resistance
Stone is cut or hewn from large blocks which have been cut, blasted or split from
Parc Guell, Barcelona, Spain.Architect:Antonio Gaudi
Material selection
the bedrock. Being a natural material,the
Natural stone is a brittle material
appearance and durability of stone,even
that is strong in compression but is weak in
from the same block. can vary enormously,
tension. It is used mostly for wall facings and
To control quality, it is sometimes best to
pavings,although the high unit cost means
select cut stone at the quarry. Since no two
that it is rarely used in a traditional loadbear-
cuts produce the same appearance, when
ing capacity.Most stone has the strength and
defining the required quality it is advisable
durability of block and brickwork.The most
to define a limit ed band between the most
widely used types are granite, limestone,
veined and leastveined stone acceptable,As
sandstone, marble and slate. Igneous rocks,
stone is a naturally occurring material, the
such as granite, are formed directly from
properties are not as controlled as man-
molten magma. Sedimentary rocks, such as
made materials such as steel.Sto ne from
limestone and sandstone, are made up from
a particular quarr y is usually t ested before
the eroded elements of earlier rocks laid
sale in order that its physical and mechanical
down in beds near the earth's surface, and
properties are known,W hen stone is used in
are often composed of loose material bound
structural applications, the material undergoes
together by cement-like materials. Meta-
rigoroustestingto detenrnine its perfonrnance
morphic rocks, such as slate and marble,are
in the intended application.
igneous or sedimentary rockswhich have undergone a chemical transformation due to
Natural stone has the following properties common to most types: Above. Parc Guell, Barcelona.Spain. Below. Casa Batillo, Barcelona, Spain.Architect: Antonio Gaudi
52
Granit e, within the building industry,
· Durable
refers to coarse-grained igneous rocks. It has
· A heavy material, weighing as much
a wide range of colours,and is extremely
as reinforced concrete.
hardwearing. Most granites are grey or pink.
· High compressive strength.
with mixtures of white/grey and pink/grey
· Low tensile strength.
depending upon their geographical source.
· Finish can be adversely affected by
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high temperature and pressure.
Limestone is made up from rock
weathering due t o exfoliation as a result of a
material bound together by calcium car-
freeze/thaw cycle, pollution,salts,etc.
bonate, in the form of the mineral calcite.
· Low moisture movement.
Manylimestones contain a proportion of
· Brittle, but high impact resistance
the mineral dolomite.The colour is gener-
improving with thickness.
ally light, ranging from near white through
· High fire resistance.
to brown and grey. Chemical impurities can
Pare Guell, Barcelona, Spain.Architect:Antonio Gaudi
cause a darkening of the colour. Limestones vary intexture and can range from a sand-
Casa Batillo, Barcelona, Spain.Architect:Antonio Gaudi
resultof oxidation.
mould. It is used either as a structural mate-
Slate is a crystalline rock produced by
rial or as a facing to a concrete component.
textured and coarse materialto one that
dynamic metamorphism of clays and shales,
Stee l reinforcement is used if the casting has
is so fine-grained as to lack visible particles.
causing it to be orientated along a single
a structural function.
Limestones such as Portland Stone (Indiana
grain or 'slaty cleavage' which allows the
Limestone inthe US) are strong and durable.
rock to be split into sheets. It is used mainly
Reconstituted stone has the following prop-
for roof slates and for durable surface fi n-
ert ies:
quartz grains cemented together by mine:al
Most sandstones consist mainly of
ishes such as floors.The colour of slate varies
·Very durable.
solutions. Calcareous, dolomitic, ferruginous
from grey to green to black to red.
· A heavy material,weighing as much
and siliceous cements are common. Small amounts of other minerals,often iron compounds,give the stone its colour. Sandstones
as reinforced concrete.
Working with the material Sto ne is shaped either by cutting or
· High tensile and compressive strength.
vary in colour from dull crimson to pink or
sculpting, which is a slow and difficult proc-
· High impact resistance.
green/brown mixtures to blue/grey Sand-
ess. Metal fixings inthe form of brackets and
· High fire resistance.
stones vary enormously in durability from
dowels are used where the mortar joints do
· Susceptible to shrinkage like concrete.
soft, easy to work types with low strength
not provide sufficient stability for lintels and
and high porosity. to relatively durabletypes
copings.These fixings are used extensively in
Properties and data
with strengths approaching those of granites,
stone cladding panels where the material is
The main properties of stone are as follows:
with lower porosity.
supported by a structural frame.
Marb le is a metamorphic rock formed
Stone has a very different appearance
Density:
by the recrystallisation of limestone or dolo-
when polished,though not all types benefrt
Natural stone: 2200 to 2600 kg/m3
mite through a combination of heat and
from the process. Depending upon type and
( I 37 to I 62 Ib/ft3) wet
pressure.The crystalline structure is seen in
appl ication, stone can be fi nished to different
Cast stone: 2 100 kg/m3 ( I3 I Ib/ft3)
a fractured surface,which gives it a sparkling
levels of sheen from a reflective polished
Characteristic compressive strength: Granite = 30 N/mm 2 to 75 N/mm 2
appearance. During metamorphism,impuri-
fi nish to a matt honed finish. Polishing does
ties in the original limestone, such as differ-
not change the structure or weathering of
ent minerals, are incorporated into the rock
stone and is typically applied where stone
and appear as bands or as discrete inclusions
is used as a floo ring material. Additional fi n-
scattered through the calcite mix. No true
ishes include etching and needle gunning, but
marble shows fossils.veined marbles are
stone used externally usually has no addi-
(6.3 x 105 to 1.5 x 106 Ibf/ft2) Sandstone = 10 N/mm 2 to 30 N/mm 2 (2.0 x 105 to 6.2 x 105 Ibf/ft2) Coefficient ofThermal Expansio n = 7.9 x 10-6 K-I (4.4 x 10-6 OF-I )
the result of mineralsdeposited from solu-
tionaltreatment after being cut to size.
Therm al conductivity = 1.0 W /m C to I.3 W /m C
tions penetrating cracks and fissures. Some marbles contain fragments of earlier crushed rocks.A wide range of colours and textures
o
o
Reconstituted stone
(0.58 to 0.75 BTU/hr.ft.0 F)
Reconstituted stone, also referred to as
may be found.The presence of iron gives
cast or 'reconstructed' stone, is made from
rise to shades of yellow, brown and red as a
cement and crushed stone that is cast in a MCH
53
Materials Brick
aI
Above and left. Richards Medical Centre,University of Pennsylvania, USA. Architect; Louis Kahn
Production process of raw material Bricks are made by cutting or moulding clay. They are then baked in a kiln to form
are to be avoided. Bricks are economically and easily transported in large or small quantities.
a hard, brittle unit.A very wide range of colours and textures is available, from the
Brickwork has the following general proper-
precisely dimensioned. evenly coloured types
ties:
which are wire cut from a clay extrusion
· A heavy and durable material.
to the less regular handmade bricks which
· High compressive strength.
are individually formed in moulds. Extruded
· Very low tensile strength.
wirecut bricks are somet imes made wit h
· High resistance to weathering.
holes runningthrough them to reducetheir
· High thermal mass.
weight or to allow reinforcing rods to link
· High acoustic mass.
them together. Hand-made bricks often have
· High impact resistance.
an uneven appearance which provides a rich
· High fire resistance.
visual texture as a completed wall. Most bricks in the UK are made in a single standard size: 215mm long x 102.5mm
· Susceptible to thermal and moisture movement. · Low seismic resistance
wide x 65mm high, (7 5/8" I. x 3 5/8" w. x 2 3/8" h.) though metric size bricks are also available. When constructing brickwork
MCH
54
Material selection The most widely used types are com-
a IOmm joint is used throughout,resulting
mon, facing,engineering and calcium silicate
in vertical courses 75mm high and 225mm
bricks. Common bricks are the weakest type,
long.Two bricks laid side by side with a
while engineering bricks are the strong-
IOmm joint are equal to a brick length.The
est. Facing bricks are usually used on the
modular nature and size of bricks makes
external face, while cheaperbricks can be
brickwork a very flexible medium.The
used within the wall. Engineering bricks are
weight and size of one brick allow it to be
used for their high strength and are almost
lifted with one hand.The modular nature of
impervious to water;and so are often being
brickwork imposes a strict discipline on the
used below ground in addition to structural
detailing of openings and corners if expen-
applications where brick is used as a primary
sive specially shaped bricks. called 'specials'
loadbearing element. Calcium silicate bricks
Richards Medical Centre,University of Pennsylvania,USA.Architect;Louis Kahn
are made from a mixture of sand and lime
Properties and data
which are compressed under steam pres-
The main properties of brick are as
sure in a mould.They are low to medium
follows:
strength, and their water absorption is comparable to that of clay bricks.They are
Density:
mainly used in internal wallswhere their light
Average brickwork = 1700 kg/m3
appearance can be exploited. Brickwork is
( 106 Ib/ft3)
strong in compression,but is not used to
Design strength = 5.0 N/mm 2 to 25.0 NI mm 2
resist tensile forces.
(1.0 x 105 to 5.0 x 105 Ibf/ft2)
Working with the material
Coefficient ofThermal Expansion
= 5.0 x
fixings, in the form of brackets and dowels,
10-6 K- I to 8.0 x 10-6 K-I (2.8 x 10-6 to 4.5 x 10-6 OF-I)
are used for wallswhere the brickwork
Thermal conductivity: = 1.3 W /m C at
Brick can be easily cut and drilled. Metal
Above and below. Indian Institue of Management. Ahmedabad.India.Archit ect Louis Kahn
o
would not be sufficiently stable by itself.
5% mo isture content (0.75 BTU/hr.ft.0F)
These fixings are used extensively in brick
Specific heat capacity= 800 Jlkg C (0.19
cladding which is supported by a structural
BTU/lb OF)
o
frame. Bricks are made in a vast range of colours from reds to blues. Colour is defined by the type of clay, combined wit h the way it is fired and any pigments which may be added. Calcium silicate bricks are white. As new brickwork and mortar dries out after rain,traces of salt deposits are sometimes left on the surface.These appear in the form of white stains known as efflorescence. It can be easily removed wit h a brush and water. W here moisture continuesto penetratethe brickwork this efflorescence will continue to manifest itself. MCH
55
Materials 0 I Tectonics in plastics
Casa Batillo, Barcelona, Spain.Architect:Antonio Gaudi
Mound Stand, Lords Cricket Gound, London, UK Architect: Hopkins and Partners
The use of plastics is very much a part of
Monsanto Houseof t he Future, Disneyland, Califoma,USA
~
).;- "
,".
\
Vemer Panton Chair
MCH
56
garden context.
recent history from 1945. Plastics were given
Later during the 1960s, the Archigram
an impetus for development during the Sec-
Group in the UK explored this t emporary or
ond World W ar and found wider industrially-
mobile nature of construction, with its ability
based uses in building construction from the
to create, at least potentially, the Instant City
1950s onwards.The Monsanto House of
or Walking City. An additional appeal of this
1957 was developed by an American hous-
archit ecture is its ability to form an addit ion
ing company wit h the Massachusetts Institute
to an existing built context along with its
ofTechnology (MIT).The aim ofthe project
ability to create a complet e built environ-
wast o create an all-plastic house that also
ment In parallel with the work of Archigram,
used much more plastic in its interior fittings,
the ecology movement wasemerging at this
which were already being used extensively in
time asa result of concern for the natural
more traditional construction,from vapour
environment, and our impact on it, gradually
barriers to plastic plumbing and electrics.The
rising in the public consciousness.An inter-
design of t he Monsanto House extended
est in a return to 'low' energytechnology
the idea of the consumer product to the
began to emerge at this time, with events
building itself by making the house from a
such as the image of the earth being seen
series of plastic 'pods'formed from wall and
from the moon for the first time in 1969,
roof panels of repeated module.The visual
allowing usto see our world from outside its
effect of the repetition of the facade panel
boundaries.The revived int erest in the flying
was reduced by setting them around a single
machines of Leonardo deVinci at the time
core, giving them a visual complexity where
can also be seen as a kind of hope for the
each room is seen as a separate volume.
future: low energy machinesthat might have
Each room was naturally cross ventilated,
a real technical performance.The possibili-
tho ugh the use of air conditioning was sug-
ties of low energy flight, and their parallel in
gested as a benefit in the time before the
architecture wasthe flying machine of Clem-
environmental effects of energy consump-
ent Adler in France, who developed the idea
tion became a primary design consideration.
of flying machines, following examples from
W indows were glazed however,and were
nature such as the bat, rather than the flat,
not curved,unless the opaque plastic pan-
fabricat ed components used much more
els, giving the visual effect of glazed 'slices'
successfully by the Wright Brothers. Many
through a complex single volume.A primary
of these principles would eventually find an
benefit of the house was possibly it s ability
echo in the 't ent' structures of Frei Otto, but
to move location as t he family moved from
were used to great effect in the airships pro-
place to place,which perhaps was as appeal-
posed by Archigram.The work of the Archi-
ing as its form with its suggestion of lightness,
gram Group themselves appeared t o come
almost appearing to 'hover' in its suburban
t o life for the first time at the big scale in the
Schlumberger Cambridge Research Centre.Cambridge, UK. Architect:Hopkins and Partners designs of non-Archigram architects Richard
Media Centre,Lords Cricket Gound, London, UK.Architect: Future Systems
This digital approach isgradually making its
Rogers and Renzo Piano. Plastics were used
presence felt in construction with the ability
to form the escalators in the Centre Pom-
to transfer 3D digital model files directly to
pidou in Paris of 1977. which would have
manufacturing machines.
been both heavy and difficultto fabricate in
Recent examples are limited to modest
glass. Plastics were not used elsewhere in
scale architectural compositions, but those
the building. where glass and metal panels
imagined in the design work of artist Roger
are used for their greater life span.The use
Dean in the I970swere far more ambitious.
of sheetmaterial in the designs of Archigram
which were either conceived as sprayed
in airships and tent structures was reflected
concrete onto a plastic formwork, or could
by the use of plastics in the Munich Stadium
have been made entirely in concrete.The
canopy of 1972 and the tent structures of
complex geometry of Zaha Hadid's project
Michel Hopkins in the Cambridge Schlum-
for ChaneI was suggested at a much larger
berger building and the Mound Stand at
scale in the Jade Sea painting by Dean of
Lords Cricket Ground in London. both built
1976. In Dean's work the architecture is
duringthe late 1980s. PeterCook of Archi-
continuous with the forms of nature, which
gram built his first large scale building that
would suit a range of materials. but plastics
reflected some of the values of Archigram in
suit the transition from complex mould to
the Kunsthaus in Graz, Austria. completed in
complex weathertight form which is difficult
2003. Acrylic rainscreen panels were curved
to achieve with other materials.
to createa non rectilinearform that creates a translucent outer skin. The abilityto cut plastic based fabrics
Olympiapark, Munich. Germany.Architect:Frei Otto
Above.Olympiapark, Munich.Ge rmany.Architect: Frei Otto Below. Eole fiying machine. Clement Ader
A possible developmentfor plastics is that of the useof common components for walls and fixtures and fittings. so that
into different forms has been exploited in
the interchange of cladding for elements of
the Natural Ellipse building by Masaki Endoh
curved wall could be used in associated fit-
and Masahiro Ikeda inTokyo.There the trans-
ted furniture in a complete system capable
parent nature of the building is exploited to
of replacement through the life of the build-
create a complex geometric building skin
ing.The life span of building components in
from a flat material. Solid plastic panels in the
contemporary buildings varies from 10years
tectonic tradition of the Monsanto House
for fittings, to 25 years for windows and
can be found in the travelling pavilion for
doors to 50-100 years for the structure.The
ChaneI by Zaha Hadid. Here.the geom-
overall life span of building elements might
etry is complex, with different sized panels
vary more by allowing more replacement
formed from a set of relatively economic
and interchangability of components within
moulds. the shapes of which could be gener-
a building rather than its complete replace-
ated from modelsgenerated in 3D model-
ment by a new assembly, or new facade. for
lingcomputer software rather than by hand.
example.Thiswould ensure that compo-
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57
Materials 0 I Plastics and composites
Allianz Arena, Munich,Germany. Architect; Herzog + de Meuron
Above and below, Natural Ellipse Building,Tokyo, Japan.Architect; Masaki Endoh and Ikeda Masahiro
nents are used for longerthan is the case in
'Composites' comprisetwo or more mate-
current building construction.
rials combined to gether where the proper-
Issues of the interchangability of com-
ties of each constituent can complement
ponents are tied to the issue of scale, and
the others.Although reinforced concrete,
design appropriate to a given scale. Where
plywood and other more traditional materi-
small structural components such as ties or
als are sometimes referred to as composites,
struts are designed quite differently to build-
the term is generally used in the building
ing beams, due to much higherforces expe-
industry to refer to polymer-based com-
rienced by large scale building components,
posites.These materials have a polymer
the difference in approach to their design is
resin reinforced with thin fibres, usually glass
shrinking wit h the need to provide greater
fibres or carbon fibres. Glass-fibre-reinforced
visual expression in large scale constructions.
polyester (GRP) was first used during the
At the scale of transportation,the design of
Second W orld W ar for radar covers and was
MIT's vehicles based on a more architectural
later applied in a GRP boat for the US Navy
approach suggests a range of components
in 1947. Carbon-fibrewas developed by the
that could be developed in plastic, from the
RoyalAircraft Establishment in Farnborough,
semi-structural seats to the enclosure of the
England, during the 1960s and was applied
vehicles.
in composites for use in compressor blades
Production process of raw material
fibre-reinforced polymer is much stronger
'Plastics' are resinou s polymer-based materials divided into two groups.These are thermoplastics, which melt at high tempera-
in jet engines later in that decade. Carbonand stifferthan GRP but remains extremely expensive in relation to most metals or other plastics and has yet to find a significant use in building construction.
ture, andthermosetting plastics,which set hard and do not melt on further reheating. They are used mainly in cladding systems but composites are beginning to be used as
MCH
58
Polycarbonate Polycarbonate is used in building con-
fully structural materials in relatively modest
struction largely as a substitute for glass,
applications such as footbridges.The most
especially where moulded shapes are
commonly used types, under the generic
required which would be too difficult or
names used in the building industry rather
too expensive to make in glass.The material
than their polymer-based names,are as fol-
was first made in the I950s as part of the
lows;
research into polyesters and was marketed
· Polycarbonate
as Lexan sheet in the early I960s. Polycar-
· Acrylic sheet
bonate is made by polymerisation, where a
· PVC-U
polymer is melted and extruded into strands
Allianz Arena,Munich, Germany. Architect; Herzog + de Meuron
which are chopped to produce polycarbonategranules.The granules can then be
Centre Georges Pompidou, Paris, France.Architect; Renzo Piano and Richard Rogers
Material selection Polycarbonate is a thermoplastic used
extruded or moulded to form single sheet,
for its high strength, ductility, lightness and
twin-wall sheet or complex shapes.
transparency. It is fire retardant, and can be easily mouldedto complex shapes.The use
Properties and data
of polycarbonate is limited by its combusti-
Density: 1200-1260kg/m 3
bility. Polycarbonate is an extruded materal
(75 to 78 Iblft))
used as sheets and sections. Polycarbonate
=
56N/mm 2 to 75NI
Tensile strength mm 2 (1.2 x 10 6 to 1.6 x 106 Ibf/ft 2)
sheet is available in thicknesses from 2mm to
Compressive strength 120N/mm 2
higher thanthat of toughened or laminated
= I 00N/mm 2 to
25mm (I I 16in to Iin). Its impact resistance is glass.The two main disadvantages of polycar-
(2. I x I0 6 to 2.5 x I0 6 Ibf/ft 2)
bonate over glass arethat it is less durable,
Young's Modulus 2.3 - 2.8kN/mm 2 (4.8 x 107 to 5.8 x 107 Ibf/ft 2)
scratching easily which makes the surface
=
Coefficient ofThermal Expansion : 60-75 x I0- 6 K-I (33.5 x 10-6 to 42 x 10-6 OF-I)
dull wit h time and its greatercombustibility. Polycarbonate also has greaterthermal expansion than glass. Twin-walled sheet is an extrusion of two layers separated by parallel fins, giving the
Thermal conductivity : o
0.18 - O.22W/m C (0.1 to 0.13 BTUI
material greater rigidity for use as a board.
hr.ft.°F)
The air gap between the two layers provides
Specific heat capacity 0
Centre Georges Pompidou, Paris, France.Architect: Renzo Piano and Richard Rogers
= 1200 -
I 300 JI
kg C (0.29 - OJ I BTU/lb OF)
a degree of thermal insulation.The maximum sheet size is approximately 2 x 6 metres. It can be sawn, cut and drilled. It expands 20%
Polycarbonate has the following general
more than glass. For example, a 1.5 metre
properties;
(5ft) wide sheet will expand up to 3mm
· A strong material with low stiffness. · High transparency can be obtained.
( I/8in).The material has a density of 1200 kg/m3, which is halfthat of glass, alt hough in
· A tough but ductile material.
practice the real weight saving is about one
· High impact resistance.
third.
· Flame resistant, tendingto melt rather than ignite, but is still combustible.
Above and below.Chanel Contemporary Art Container Mobile.Architect:Zaha Hadid Architects
Polycarbonate can be coated wit h acrylic to prevent yellowing, and other coat ings are
· Poor scratch resistance wit hout silicone
used to enhance abrasion resistance. It pro-
coatings.
vides an average of 85% lighttr ansmission
· Recyclable.
for a sheet 5 to 6mm thick.
MCH
59
a
Materials I Plastics and composites
ChaneI Contemporary Art Container, Mobile.Architect:Zaha Hadid Architects
ChaneI Contemporary Art Container, Mobile. Architect:Zaha Hadid Architects
Acrylic Sheet
· Easily recycled.
Acrylic sheet,developed as Perspex in
· Combustible.
the I930s, isa plastic based on polymers of acrylic acid.The mostcommon ispolymethyl methacrylate, or PMMA, made by polymeris-
rvcu
ing an MMA monomer with a catalystto
Theterm PVC-U, or UPVC,denotes
form a powder which can then be extruded,
the unplasticised form of polyvinyl chloride,
moulded or cast.
or PVC.This rigid form of PVC isused for a wide range of building components from guttering and ground drainage pipesto
Kingsdale Foundation School, London, UK.Architects:dRMM
Properties and data
window frames.The material can be easily
Density: I 150 -2000kg/m 3 (72 to 125 Ib/ft 3)
extruded or moulded to complex shapes
Tensile strength mm 2
=
and is available in a range of colours.The
38N/mm 2 to 80NI
the material combined with its ability to be
(7.9 x 105 to 1.7 x 106 Ibf/ft2) Compressive strength
80N/mm 2
extruded makes it very suitable for window
=
45N/mm 2 to
frames where the material is, in effect, its own thermal break,minimising the riskof
(9.4 x 105 to 1.7 x 106 Ibf/ft 2)
condensation on the face of the frame inside
Young's Modulus 1.8 - 3.4kN/mm 2 (3.8 x 107 to 7.1 x 107 Ibf/ft 2)
the building.
=
Above. Olympiastadion, Munich,Germany. Architect: FreiOtto Below. Natural Ellipse Building,Tokyo,Japan.Architect: Masaki Endoh and Ikeda Masahiro
low thermal conductivity and fiexibility of
Coefficient ofThermal Expansion 60 x I0- 6 to 70 x I0- 6 K-I
Properties and data
(33.5 x 10-6 to 39 x 10-6 OF-I)
Density : 1400kg/m 3 (87 Ib/ft 3)
o
Thermal conductivity: 0.2 W1m C (0.1 I BTU/hr.ft.OF) Specific heat capacity
= 1280 -
o
1500 J/kg C (0.30 - 0.36 BTUI
=
Young's Modulus 0.1 to 4.0 kN/mm 2 (2.1 x 106 to 8.3 x 107 Ibf/ft 2) Coefficient of Thermal Expansion 70 x I0- 6 K-I (39 x 10-6 OF-I)
=
Ib OF)
Thermal conductivity
Acrylic sheet hasthe following general prop-
Specific heat capacity
erties:
(0.30 BTU/lb OF)
°
BTU/hr.ft. F)
=O.3W/m C o
(0.17
= I 300 J/kg C o
· High transparency and optical clarity.
MCH
60
· Weathers well wit h high resistance
PVC-U has the following general
to yellowing.
properties:
· Hard but brittle.
· Available in a range of colours.
· Poorscratch resistance.
· Weathers well but is susceptible to fading,
ChaneI Contemporary Art Container, Mobile. Architect: Zaha Hadid Architects
Beijing National Aquatics Centre, Beijing, China.Architect: PTW Architects
particularly with brighter colours.
(0.23 to 0.7 BTU/hr.ft.0F)
a machine-based industrial technique. It is
·Tough but flexible.
Specific heat capacity
formed in moulds but without high tempera-
o
= I00 - 1400 JI
· Recyclable.
kg C
tures or expensive equipment.This is in con-
· Combustible.
(0.02 - 0.34 BTU/lb OF)
trast to the emerging technique of pultrusion
GRP has the following general properties:
where machinery is used to draw a mixture
· Strong but light.
of resin and chopped fibres through a die
· High stiffness compared with plastics.
to produce a material with constant cross-
· High impact resistance.
section. A wide range of sections is now avail-
Glass Reinforced Polyester (GRP) This material was first commercially available in the 1930s from the Owens-Corning
able from I-sections to channels,tubes and
Fiberglas Co in the USA, but has only slowly
planks for use in footbridges. Sections can
been introduced into building. Its main use is in specially fabricated wall cladding panels. Glass reinforced polyester; or GRP, is made
Working withthe material GRP is made by embedding glass fibres,
be bolted together using techniques broadly similar to those used in steel construction.
usually as a woven cloth, into a polyester
from a combination of glass fibre mat and
resin which arethen hardened by a catalyst.
polyester resin. It is a thermosetting compos-
Glass fibre is a flexible sheet material formed
ite which has high tensile, shear and com-
from fibres drawn from molten glass,and
pressive strength combined with lightness
has a tensile strength ten timesthat of steel.
and resistance to corrosion. However; like
Polyester resin, the other componentof GRP,
aluminium, it deflects considerably under high
becomes a solid material when a chemical
loads and requires stiffening.
catalyst is added.The material is made either by craft-based open moulding methods to make panels or by pultrusion to make
Properties and data
continuous sections in the mannerof extru-
Density : 1600-1950 kg/m 3 ( I00 to 120 Ib/ft 3)
sions in other materials. Injection moulding
Tensile strength = 300 N/mm2 to I 100 N/mm2
is sometimes used but this is usually limited to small components.The craft-based methods use either the hand lay-up technique,
(6.3 x 106 to 2.3 x 107 Ibf/ft 2)
where glass-fibre or glass-fibre cloth is laid
Compressive strength =360N/mm 2 to
in an open mould and coated with resin
880N/mm 2
and catalyst. or the spray technique where a
(7.5 x 106 to 1,8 x 107 Ibf/ft 2)
mixture of fibres and resins is sprayed onto
Young's Modulus : = 35 - 45 kN/mm 2 (7.3 x 108 to 9.4 x 108 Ibf/ft2)
the mould.Air bubbles are removed by handrollingor by a suction method.The face of the mould is coated with a releasing agent to
Coefficient ofThermal Expansion : 8.5-25x I0- 6 K-I
facilitate removal when set.
(4.8 to 14.0 x 10-6 OF-I) o
Thermal conductivity: 0.4 - 1.2W/m C
The manufacture of GRP panels is a craft-based workshop activity rather than MCH
61
Materials 0 I Tectonics In timber
The Eduardo Catalano House, Raleigh,North Carolina, USA.Architect: Eduardo Catalano
Vanna Venturi House, ChestnutHill, Philadelphia, Pennsylvania, USA. Architect Robert Ventur i
An increased int erest in the use of
rial that can provide a smooth continuous
timber is in gridshells, which are shown in
surface to contrast with the glazing rather
the structures chapter. In contrast to large
than allow the specific form of construction
scale structures currently being developed in
t o be expressed.This approach follows a
new projects is the enduring use of timber
Modernist interest in linking inside and out-
to make small-scale rectilinear enclosures
side spaces across screens of glass, through
based on cut timber sections up to around
the use of the 'open plan' of linked internal
3.5 metres long,condit ioned by the size of
spaces. In Meier's houses, spaces are dif-
cut natural timber,which conditions the size
ferentiated by the introduction of double
of rooms in domestic construction.The 19th
heightvolumes that link spaces together to
century British railway was designed with
differentiate spatial experience in a building.
this constraint,to make an economic single
This is a different approach t o the spatial
room buildingthat can be glazed along its
complexity of house projects designed by
walls as required to give clear views up and
Meier's contemporary Pet er Eisenman, for
down the railway track.A 20th century echo
example, who introduced a second overlaid
of this building type is the VannaVenturi
grid into his designs for timber buildings to
House designed by Robert Venturi and com-
create spatial complexity while following
pleted in I964.The design can be viewed
regular construction methods for this mate-
as a reaction to the 'free' plan of Modernist
rial.The use of a second grid at a different
architecture. In mainstream Modernism, the
angle, used by Eisenman, follows on to some
design is generated from the plan,providing
extent from the work of Louis Kahn, with his
buildings which are largely extr uded from
'buildings wit hin buildings' ideas in the Exeter
the plan. Instead,Venturi'st imber buildings
Library and the Indian Institute of Manage-
ofthe 1950s draw on vernacular'types', so
ment in Ahmadabad.
that buildings might look like their imagined
Teatro del Mondo, Mobile. Architect:Aldo Rossi
MC H
62
Leigh-Pemberto n House, Lincoln,UK
A contemporary of both architects is
typologies as well as being specific to their
Aldo Rossi, whose interest in simple geo-
sit e, rather than being largely independent
metric forms can be seen in his design for
of the historical built context. Consequently.
the mobile t heatre, the Teatro del Mondo,
a school should look like a 'school';a house
with its independence from context, allow-
should look like a tradit ional home, with
ing an abstracted typology of theatre to
communal spaces on the ground floor and
become the primary forms of archit ectural
private rooms on the upper floor.
expression in the design. Here the t imber
In contrast t o this approach are the
construction is used in the form of long tim-
early homes of Richard Meier,using timber
ber boards to create large flat surfaces, with
construction for Modernist designs, often
timber framed windows set into them.The
contrasting open glazed facades with opaque
design follows traditional principles of timber
enclosedwalls.Timber is used as a mate-
construction at this scale.
Signal Box
Another strand of timber construction is
achieve considerably higherperforming walls
that of traditional timber shipbuilding, where
using the same principle.This approach may
large scale structures, the equivalent of
be one to follow in the comingyears.
three or four storey buildings, were formed
A mixture of large scale timber con-
in shapes of complex geometry required
struction and its smaller scale platform frame
to propel them through water efficiently.
equivalent can be seen in traditional Japa-
An essential feature of traditional shipbuild-
nese construction, where timber frames vary
ing, particularly for fighting ships, is the solid
in scale to suit both their structural purpose
nature of their construction, more likethe
and their use wit hin a building.The use of
solid cross laminated timber panels of con-
pegs and interlocking joints to createjoints
temporary construction than the frame with
that work in tension as well as compression
lightweight timber cladding attached. Sailing
have produced a rich tradition of hand built,
ships of the 18thand 19th centuries had
large scale structures seen in the design of
thick timber hulls clad in additional timber,
sailing ships immediately prior to the Indus-
rather than having a skeletal frame with
trial Revolution.
timber boards spanning between them.This
A contemporary parallel of this
form of construction can be seen as a paral-
approach of mixed timber techniques can be
lel to the solid hardwood timber frames of
seen in the early work of Morphosis Archi-
medieval construction, which are seeing a
tects in the US.Their early unrealised designs
revival in England.The timber frames use
have small scale structures are linked in a
timber sections of around 300mm square,
building composition that would have ideally
typically set at around 2000mm centres,
suited this approach of mixed timber con-
rather than the small softwood timbers of
struction.The designs, while visually striking,
IOOmmxSOmm set at 300mm centres or
do not exceedthe limits of the construction
less. However; the constructional sophistica-
material which would have required addi-
tion of sailing ships is only just beginning to
tional structural support in a different mate-
find its way into contemporary solidtimber
rial system.The use of small scale structures
frame construction.
to create largerbuildings from these compo-
Unlike sailing sips, which were entirely clad in timber on the outside, sometimes with an additional thin metal skin on the
Instant Cabin at MassachusettsInstitute ofTechnology (MIT).
nentsavoidsthe need to change material or use laminated timber. Tension joints in timber are difficultto
lower part of the hull, medieval timber con-
form without metal connectors or glues,
struction of buildings sets the cladding mate-
but the ability to form joints without their
rial as an infill between the structural mem-
use has been explored in the design of the
bers. While historically this resulted in cracks
Instant Cabin at Massachusetts Institute of
between structural frame and infill, causing
Technology (MIT).The form of construction
possible leaks. contemporary materials can
used is one of interlocking components and
Napier University,Edinburgh,UK. Architect: Building Design Partnership
MCH
63
Materials 0 I Timber
Examples showing a parallel timber technology:theconstruction oftimber sailing ships. pegs all formed from plywood sheet. While
appearance, usually resulting from knots
experimental, this design demonstrated the
which weaken the timber. Knots are actually
possibilities of construction based on the use
where the branches were located and leave
of digital tools for both design and construc-
a distinct pattern in the cut timber.
tion.The plywood sheets were cut with a
. Timber is prone to rot, particularly where it
CNC router in a way that produced little
cannot be adequately ventilat ed or is subject
waste material by layingout cutting patterns
to continuous cycles of wetting and drying.
in a digital file used by the cutting machine.
'Theoret ically, wood will lastforever if it stays
This approach of CNC routing can be
either completely dry or completely wet.
approximated at the smaller scale through
Wooden piles rot only in the area of fluctua-
the use of lasercutters to make small scale
tion in the water table or tide.The causes of
models of the real components.This method
decay are a mixture of trapped air and water,
of rapid prototyping is ideally suit ed to
where fresh air cannot vent ilate and dry the
timber construction, where issues of fabrica-
wet material.This results in the growth of
tion in the real building can be studied and
fungi, causing dry rot, or insectattack.This is
resolved during the design development
prevented by impregnating the outer zones
of the building.This contrasts with other
of timber with preservative chemicals, but
machines used for rapid prototyping, which
these can harm the natural environment if
provide ways of making sometimes complex
the chemicals are allowed to leach into the
forms in an unspecified building material. An
ground.
essential aspect of digital fabrication techniques in timber istheir ability to bring the full range of design development backto the
Material selection Commercial timber is classified as either
design studio, allowing constraints of material
softwood, from conifers, or hardwood, from
systems in timber to inform the design at all
broad-leaftrees.Softwood is used for most
stages of development.
structural timber,as it is easily worked due to its softness and straightness of grain,
MCH
64
Timber has the following general properties:
tural timber frames.Typical types are cedar,
though oak is common for exposed struc-
· Fibrous and elastic, making it strong in
Douglas fir, western hemlock, pine,redwood
tension and compression. Like metals, it per-
(scots pine), spruce, whit ewood and yew.
forms better in tensionthan in buckling.
Most softwood comes from the coniferous
· Undergoes varying degrees of moisture
forests of the northern hemisphere. Hard-
movement.
woods have high strength and durability, a
· Straight grain is strongerthan an irregular
rich grain and varied colour.They are more
grain and is easier to work.
expensive than softwoods which makethem
An irregulargrain gives a rich,textured
too expensive for most current structural
use, but suitable for joinery and finishes.
grade, exterior grade and marine grade.The
Typical variet ies of hardwood are ash, beech,
face veneer s vary from a rough finish, such
birch, cedar,iroko , mahogany.maple, oak, teak
as Douglas fir to a smooth one like birch.
and w alnut. Hard wood occurs in most parts
The different veneers have little influence
of the wo rld but is obtained mainly from
on either moisture penetration or strength.
both northern temperate forests and tropi-
Because plywood performs well in shear, it
cal rainforests.Since hardwoods constitute a
is used as sheat hing to timber w all panels.
large proportion of the rainforests, and take
Plywood also has high impact resistance. It
much longer to grow than softwoods, the
can be bent to small radii, somet imes using
wo rld's supply is depleting at an alarming
a steam treatment.
rate .As a result, the use of certain tropical
Recent developments in plywood have
hardwoods has come under considerable
produced blockboard and laminboard w hich
scrutiny in recent years.
are made by applying veneers to a core
Laminated timber is constructed from
made from solid timber core blocks also
planks glued together to form sections
known as a stave-core The core consists
w hich are larger than could be achieved
of strips of solid w ood ranging from 7 to
w it h natural timber. Laminated timber works
30mm (I /4in to I 3/ 16in) thick. Laminboard ,
well in both tension and compression.As
a heavier material than blockboard , has a
the natural growth defect s of timber reduce
core of solid strip s up to 7mm
(I /4in) thick,
strength, individual board s are positioned so
laminated together. The grain of the face
as to reduce the cumulative effect on th e
veneers is set at right angles to that of th e
strength of the overall member.The strength
core strips.These boards are not suitable
of laminated timber therefore approaches
for forming cur ves.The advantage of th ese
th at of defect-free so lid timber.
panels is that the y are lighter and cheaper
Ply wood sheet w as invented in the
than plywood. Laminboard is useful w here
USA in the I 930s, and is made by bonding
w eight is important, but is unstable in w et
together veneer s peeled from logs. Both
areas because the endgrain to the blocks is
softwoods and hardwoods are used.The y
exposed w hich can deteriorate rapidly.
are layered so that the grain of each veneer
Chipboard, medium density fibreboard
is set at right angles to the one either side,
(MDF) , and hardboard are the most
providing strength in both directions as w ell
common particleboards. All are made
as minimising thermal mo vement. Good
from mixing w ood particles, normall y
quality plywood has very little thermal
wood w aste, w it h an additive to form
movement. Ply wood is graded according
a sheet material that is cured between
to its resistance to moisture penetration
heated plates. Chipboard w as developed
w hich is determined mainly by the glue
primarily for the furniture industry in the
used.The most common t ypes are interior
I 960s. However, it is also used as a flooring MCH
65
Materials 0 I Timber
Japanese Timber Framing
Halcyon Beach Hut, Sutton on Sea. Lincolnshire,UK. Designed by Atelier NU
Sea Ranch Chapel, California. Designed by James Hubbell
material in wood construction as a cheaper
way. Both fixingstransmit shear forces at the
alternative to plywood or timber boards.
joint across the bolted connection.
Chipboard is not as strong, or as rigid, as
Great CoxwellTit he Barn, Oxfordshire,UK
The nail-plate, also called a gangnail
an equivalent plywood sheet since the
plate, is a galvanisedt hin metal plate which is
wood fibres are shorter.Like plywoods, it
pressed to form a series of nail-like projec-
resists shear forces but is less capable of
tions on one side.The plate is pressed into
withstanding impact damage and is harder
the timber sections being joined to form a
to fix wit h screws and nails. Also, it cannot
patch connection on either side.This is done
be curved except in a pre-formed process.
under factory-controlled conditions, and is
Chipboard is also more prone to creep
most commonly used in prefabricated floor
under prolonged loading than plywood
and roof trusses.
and timber. MDF has smooth faces and a
Glued connections in timber are glue-
uniform cross section.This gives it a great
welded joints that are as strong as the wood
advantage over other boards of having
itself W idely used typesare urea-formalde-
smooth exposed edges that require no
hyde, phenol-formaldehyde and resorcinol.
lipping or trim when cut. For this reason it is
Glued connections provide structural con-
often used for built -in furniture and interior
tinuity at the joint.They do not break down
panel systems.
when exposed to the weather or changes in temperature.
Wo rking with the material Before the 20th century most timber
Westminster Hall Ceiling,the Houses of Parliament. London,U K
joint s were made to work in compression,
to be made quickly and efficiently tend to be
so the high tensile strength of the material
used. Most joints are designed to be manu-
was not used at junctions. However, the
factured easily using machinery, which has
development of modern gluesand metal
led to the demise of traditional t echniques
connectors has resulted in a wide range of
such as dovetailing. However, the availability
contemporary tension and compression
of adhesives has enabled simple mitred and
joints.The most common joints in timber
butt joints to be used.
that perform well in tension and compression are the bolted metal connector, split ring connector and the nail-plate connector. The bolted connector is a thin plate of galvanised steel with projectingt eeth.The connector is set between the timber sections being joined, and is embedded into both sections as the bolt fixing is tightened. The split ring connector works in a similar MCH
66
In joinery, particularly for built-in it ems, simple jointing techniques that allow parts
Sea Ranch Chapel, Califomia. Designed by James Hubbell
Properties and data Density:
=3.9 kg/m 3 (0.243 Ib/ft3) Mahogany type hardwood =7.5 kgl m3 (0.47 Ib/ft 3) Pine softwood
Design strength:
=5.3 N/mm (1.1 x 105 Ibf/ft2) Mahogany type hardwood = 12.5 N/mm (2.6 x 105 Ibf/ft2)
Pine softwood
2
2
Young's Modulus
= 10 kN/mm
2
(2.1 x 108 Ibf/ft 2)
Coefficient of thermal expansion: Pine softwood 34 x 10-6 K-I across grain (19 x 10- 6 F-I) 3.5 x 10-6 K-I along grain (1 .9 x 10-6 F-I) Mahogany type hardwood = 40 x 10- 6 K-I across grain (22.2 x 10-6 F-I) 4.0 x 10- 6 K-I along grain (2.2 x 10-6 F-I)
=
Thermal conductivity:
=0.14 W/moC across grain (8.1
x 10-2 BTU/hr:ft.0F) Mahogany type hardwood = 0.21 W /moC across grain (12.1 x 10-2 BTU/hr:ft. OF) Pine softwood
Specific heat
Eltham Palace Hall, Eltham, London, UK
= 3.0 J/ktC (7.2 x 10-4 BTU/lbOF)
Standard sheet sizes:
Plywood
1220 x 2440mm (4'x8') 1525 x 3660mm
Thicknesses 4mm to 25mm (1/4" to I") Chipboard
1200 x 2400 mm I200 x 4800mm Thicknesses 4mm to 25mm (1 /4" to I")
MDF
1220 x 1525mm 2440 x 3050mm Thicknesses 4mm to 25mm (1 /4" to I")
Hammerbeam Roof, Stirling Palace.Scot land, UK
Materials 0 I Fabrics and membranes
Sainsburys Petrol Station,Canley, Coventry, UK. Architect: LDS
PVC rnernbranesrvc (polyvinyl chlo-
lat ion above that, sealed on top with a single
material, a whit e coloured translucent sheet
ride) roof membranes have been in use since
layer membrane. PVC-P membranes are
is manufactured which allows around 40%
the 1960s as a very lightweight and relatively
typically l .5mm - 3.0mm thick,while EPDM
light transmissio n. ETFE does not provide a
economic roofing material,and have become
membranes are typically 1.0mm - l .5mm
barrier t o the passage of UV light, making
widely used in recent years. Membranes in
thick.
it ideal for use in buildings where extensive
FPO (TPO) membranes
white sheet has great ly reduced UV light
this mat erial were first developed in Europe in the late 1960s and were used in the US from the I 970s onwards. PVC sheet material
planting is displayed,though the t ranslucent A recent development in thermoplastic
transmission. Solar shading can be provided
is usually reinforced with glass fibre to give
membrane types are polypropylene- and
by a pattern of dots printed onto the surface
it increased rigidity that is easier to bond to
polyethylene-based materials.They have
of the ETFE cushion, with a refiective silver
the substrat e.The PVC used in membranes
great er fiexibility than PVC-P membranes, but
colour being a popular choice,though other
is plasticised (PVC-P), unlike the unplasticised
still require reinforcement in glass fibre sheet
colours and patterns can be developed for
PVC (PVC-U, or upv q used t o makewin-
for increased dimensional stability and polyes-
individual projects. The printed dots on clear
dow frames and rainwater drainage compo-
ter fabricto give greatertensile strength. Fire
ETFE sheet reduce the light transmission to
nents. PVC-P is rigid at normal external t em-
retardant is added to provide fire resistance,
around 50-60%, but this can be increased
peratures, but softens when heated, making
unlike PVC-P which is self-extinguishing when
further by print ing dots on two faces of the
it fiexible and allowing strips or sheets to be
fiame is applied.
air-filled cushion in areas of the roof where
welded together t o form a continuous membrane without the need for standing seams
more shading is required.The amount of
ETFE
solar shading provided can be varied by
ETFE (ethylene-tetra-fiouro-ethylene)
allowing the middle layer to move as a result
in PVC-P is added to give the material great-
is a polymer similar to PTFE (marketed as
of changing the air pressure within the cush-
er fiexibility.The material has very low levels
Tefion) which is made by extrusion as a
ion.The middle layer moves either outwards
of shrinkage, and is dimensionally stable and
sheet material.Thicknesses vary but 0.2mm
or inwardsto increasethe overlap of the
does not creep visibly with age.The mate-
is a common thickness of material for ETFE
printed screen of dots that has the effect of
rial experiences only very small amount s of
cushions, allowing them to be very light in
varying the amount of solar shading provided.
movement under full wind load.
weight at around 350g/m 2 for this thickness
or visible joints. Plasticisers and filler material
The sound absorption of ETFE cushions
of sheet. Heavier gauge sheetat O.5mm
is low, so that sound travels easily through
fibre sheet or polyester fabric.These lay-
thickness weighs around 1000g/m . lnner
the mat erial.W hile this can be an advant age
ers are bonded into the material.The glass
layers of ETFE sheet that provide separat e
in noisy int ernal environments, it can be an
fibre provides dimensional stability, making it
chambers within the cushion are often made
inappropriate material if external noise is able
more stable for bondingto the substrate.The
from 0.1mm thick sheet.The material is also
t o travel through the roof to internal spaces
woven polyester fabric,used in tent mem-
used for its high level of transparency, with
where a quiet environment is required. Cush-
brane structures, has hightensile strength and
95% light transmission, and its durability
ions can also produce a drumming effect
to resist wind loads the mechanically fixed
when compared to other fabric materials,
during rain resulting from the use of a th in,
method is used. A typical build-up for a single
with a life expectancy of25-35 years, based
stretched membrane material.
layer membrane is a concrete deck with a
on visual criteria. In order to provide translu-
The t oughness of ETFE sheet is com-
vapour barrier set on top, with thermal insu-
cent areas of roof (or facade) using the same
bined with a high resistance to tear.Damage
Membranes are reinforced with glass
MC H
68
2
Busan stadium, Busan, South Korea. Architect: SpaceGroup
by sharp objects puncturing an outer mem-
carried away in the rising hot air of a fire.
from a glass fibre mat which is coated with a
brane does not spread easily into a larger
ETFE sheet meltsat around 275°C,forming
PTFE layersuch as Teflon. As with PVC/poly-
tear easily. Birds can puncture the outer
holes in the fabric which allows the heat and
ester membranes, the coating protectsthe
membrane, but they have great difficulty in
smoke of a fire to escape. However, some
fabric from the effects of both the weather
comingto rest on the roof itself, except on
roofs still require smoke vents, since this may
and UV light as well as forming a low fric-
the clamping plates, where wire is sometimes
not always OCcur during a fire if the smoke
tion surface to reduce the collection of dirt
fitted to avoid providing any spaces for birds
and heat is being generated in an area away
and dust. Most dirt is washed away by rain,
to stand.The material has fairly high resist-
from the roof, where the ETFE cushions are
but some cleaning is needed using the same
ance to surface fading from UV light where
not affected by the fire. The small amounts of
methodsas for PVC/polyester roofs.Typically
there is a gradual loss of surface reflectivity.
material used in ETFE cushions, with an aver-
it weighs 800-1500g/m 2 .The life expectancy
ETFE sheet is also highly resistant to attack
age wall thickness of 0.2mm, result in little
of a PTFE/glass fibre membrane roof is longer
from chemicals and from airborne pollu-
material being deposited during a fire.
than PVC/polyester membranes at around
tion in urban areas. Its low level of surface friction ensures that cushions do not hold
30-40 years.
PVC/polyester fabrics Comparison of types
dirt and dust easily, making cushion roofs
PVC/polyester fabrics are madefrom
relatively easy to maintain. ETFE roofs are
polyester cloth which is coated on both sides
usually cleaned as a result of rain in temper-
with a layerof PVC.The coating protects
have high tensile strength and high flexibility,
ate climates, though access for maintenance
the fabric against the effects of rain and of
making them very suitable for curved and
Both PVC/polyester and PTFE/glass fibre
is required, usually provided by walking along
UV light.The PVC coating is a mixture of
double curved roof membranes.They both
the external clamping plates with cable assist-
PVC powder, softeners and plasticisers, UV
have a lighttransmission of 5-20% depending
ance or from external structure. Roofs are
stabilisers, pigments and fire retardants.An
on the thickness of membrane used, reflect-
designed so as to ensure rainwater drains
additional outer coat of lacquer slows down
ing 75-80% of light. Neither will catch fire
easily from the roof. Gutters are introduced
the effect in the PVC coating of becoming
easily, and both resist the deterioratingeffects
on long span roofs between sets of clamping
increasingly brittle with age, which results
of UV light, though PVC/polyester becomes
plates, as shown in (F). Cushions are repaired
from the softeners within the material gradu-
increasingly brittle with age. Both have almost
by the use of ETFE tape,which isvisible,
allymoving to the surface of the PVC coating.
no acoustic performance and have poor
Or by complete replacement of the panel,
The lacquer coating also slows down the
thermal insulation performance when used
depending largely on the visual requirements
fading effects of the colour pigments. A PVDF
as a single membrane roof. PVC/polyester
of the roof design.
lacquer (a fluorinated polymer) istypically
has a greater range of colours readily avail-
A major concern in the use of polymer
used, which also ensures that the surface has
able, while PTFE/glass fibre is usually white,
materials for single layerand multiple layer
low surface friction so that it will attract little
the colour to which it bleaches naturally from
fabric roofs istheir performance in fire. ETFE
dust and dirt, and allowing the membrane
its manufactured beige colour after a few
sheetis not easily inflammable and will self-
to be cleaned easily. Acrylic lacquers are also
months of being exposed to sunlight. Weld
extinguish quickly under direct flame. Few
used.The typical weight of a roof using this
marks that occur duringfabrication also
burning fragments will fall below during a
material is 500-800g/m • A PVC/polyester
disappear as a result of bleaching in sunlight.
fire, since the material melts rather than
membrane roof will lastaround 15-25 years.
burns, with most of the burnt material being
2
PTFE/glass fibre membranes are made
PTFE/glass fibre has lower surface friction than PVC/polyester, allowing the former to
MCH
69
Materials 0 I Fabrics and membranes
Hampshire Rose Bowl,Hampshire County Cricket Club, Southampton, UK. Architect:Hopkinsand Partners
Brentwood Mall, Burnaby,British Columbia.,Canada.Architect: Musson Cattell Mackey Partnership
remain cleaner; while PVC/polyester requires
but w ill have the effect of losing most of the
cleaning more frequently. PTFE/glass fibre
light transmission through the membranes. In
requires greater care in transportation to site
addit ion, low frequency sound is difficult to
and erection than PVC/polyester; the latter
absorb due to the low mass of t he cladding
being capable of being folded wit hout dam-
material. In common wit h ETFE cushion roofs,
age t o the membrane.
the roofs are almost t ransparent to sound emitted from wit hin the building.
Thermal insulation A single layer membrane fabric roof in either PVC/polyester or PTFE/glass fibre
Mound Stand,Lords Cricket Gound,London, UK. Architect: Hopkinsand Partners
Performance in fire The performance of a membrane dur-
typically has a U-value of around 6.0W /m2K.
ing a fire depends on both the fabric used
W here tw o layered membranes are used,
and the stitchingat the seams,where this
wit h a minimum air gap of 200mm betw een
joining method is used. Membranes lose
the membranes,the U-value can be reduced
their t ension under high temperatures, w ith
t o around 3.0W /m2K. Double layer mem-
PVC/polyester st retching above 70-80°e,
branes are less commonly used as they have
and PVC/polyester seams starting to peel
a severely reduced light transmission,the
at around 100°C, At 250°C the PVC melts,
translucency of the material being one of
leaving holes in the membrane. PVC has fire
its main advantages.Thermal insulation can
retardants in the coating so that it self-ext in-
be added to a double layer membrane by
guisheswhen the flame source is removed
using a translucent fibre-based insulation, as
which results in few, if any, burning fragments
used in fibre glass cladding panels discussed
to drop down from the roof. PTFE/glass fibre
in t he previous chapter.The insulat ion can be
fabrics fail at a around IOOO°e, but seams will
fixed to the inner face of eit her membrane,
fail at a much lower temperature of around
depending on how the roof void is vent ilated.
270°C,W it h both materials, t he failure of the
Wi t h the increasing importance of the role
membrane forms holes in the roof which
of thermal insulation in the reduction of
allow heat and smoke to escape.
energy use in buildings,the use of double layer fabric membranes is set to develop considerably over the next 10years.
Membrane roof fabr ication In stitched panel joints, wider seams have more rows of stit ching visible,w it h the
Acoustics Like ETFE cushions discussed in the previous section, single layer membranes provide
Plashet Unity Bridge,Lewisham,London,UK. Archit ect:Birds Portchmouth Russum
MCH
70
mat erial folded over itself to strengthen the joint.Joint widt hs vary from around 25mm to IOOmm depending on the size of the
no significant reduction of noise through the
membrane and its associated loads.Addi-
roof. A double layer roof w it h an acoustic lin-
tional strips of fabric are usually bonded ont o
ing will provide some acoustic performance
t he outer (upper) face of the stitched seam
Food Court, Chatham MaritimeShopping Centre, Chatham,UK,Architect: Kemp MuirWealleans
'Observatory:Air-Port City 2008', Hayward Gallery. London, UK, Designer: Thomas Saraceno
to avoid rainwater penetration through the sewn thread, PVC/polyesterpanels can be stitched in conjunction with most lacquer types, Welded seams are made by forminga lap between panels,then heating the lapped areas and pressing them together. Jointwidt hs are similar to those required for stitched seams, Seams in PTFE/glass fibre panels are formed by hot element welding rather than by stitching or bonding, with an additional fabric strip added either on top
Buckingham Palace Ticket Office, London, UK.Architect: Hopkins and Partners
or within the joint itself between the membranes to provide the required strength, For welded joints on PVC membranes, the edge ofthe panel being jointed has the PVDF lacquerremoved before welding,which is applied again when the welding is complete to ensure that the PVC is fully welded and that the PVDF lacquer forms a continuous seal across the joint when formed, PVC/ polyestercan be both hot air welded and hot element welded,the advantage of hot air welding beingthat repair work and some
Ford Direct, Stevenage,UK.Architect: DWW
complex jointing can be undertaken during erection on site, Fabric roofs wit h high structural loads within the membranes can be both welded and sewn to provide a stronger joint If the joint is first sewn then welded, this avoids the need for an additional strip to be addedto the upper surface, which can enhance the visual appearance of the membrane on its outer surface, Bonding with solvents is used on PVC/polyesterfabrics only, but can be done in conjunction with most lacquers used on that material.
Chene ParkAmphitheatre,Detroit. USA. Architect: Kent Hubbell and Engineer Bob Darvas
MCH
71
a
Materials I Internal walls I: Fixed and demountable
? Details I. Block,typically concrete or hollow brick 2.Timber stud frame 3. Plasterboard/drywall finish 4. Skirt ing or recesssed tr im as shown 5. Intemal door 6. Floor joist 7. Door header 8. Stud 9. Bracing 10. Flank wall I I.Glass block 12. Bedding reinforcement I 3. Silicone seal 14. Bedding compound 15. Stud partition 16. Steel frameto enclose glass block panel
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Blockwork Partitions are non-Ioadbearing walls.The
Glass blocks Glass block part itions are built in panels
uninterru pted surface of glass.An alternat ive method is to bolt fix the glass employing
ease with which they can be removed or
of gridded blocks.The joints between blocks
methods used in external walls which are
changed depends upon the type of construc-
are reinforced with steel rods to overcome
described in the walls chapt er.To avoid the
tion. Blockwork partitions are constructed
their inherent lack of structural stability.The
problem of people walking into it, a line of
like external walls and provide high levels
rods are bedded either in a cement-based
manifestation marksis added to the glass
of sound insulation as a result of their mass.
mortar or in silicone. Edges of blocks are
where the partitions are used in public areas.
A blockwork partition istypically set onto a
sanded or coated to provide a key for the
They usually comprise a row of dots set at
concrete floor or steel beam.The blockwork
jointing material.Glass blocks can be made
eye level and are either screen printed,etched
can be left as a self-finish, if fairfaced, or given
into panels approximately two metres (6ft
or fritted onto the material.
a plasterfinish.A gap is usually left between
6in) square and can be built either in pre-
the to p of the part it ion and the soffit (under-
fabricat ed form or as sit e-built panels. Panels
side) of the floor above t o allow both for
are supported by a perimeter frame made
thermal movement in the partition and
from any structural material such as concret e,
office buildings where requirements for the
deflections in the floor above.The gap is usu-
steel or timber.Expansio n joints are provided
subdivision of space change frequently in
ally filled with a flexible strip such as mineral
around each panel.
fibreboard.
Demountable part itions are used in
responseto changing workloads and work patt erns. Demountable partit ions have been
Glazing Timber
Demountable Partitions
used for centuries in traditional Japanese
Glazed partitions comprise sheets of
construction. Sliding screens of translucent
to ughened or laminated glass fixed either in
shoji panels and opaque fusuma panels are
like the external wall to the platform frame,
a framing system in the manner of a large
used for external walls and internal partitions.
using an internal quality lining such as plas-
window, or are fixed without frames on their
When they are used externally. an additional
terboard instead of plywood sheet. Sound
top and bottom edges only. Sheets are often
outer screen often protects them.These
insulation can be provided by an infill of
made sufficiently thick to avoid the need
panels are all demountable and can create
board or quilt between the studs.An alterna-
for vertical framingmembers or mullions to
a variety of open and concealed spaces.
tive method is to build the wall as two skins
provide rigidity. For example,a IOmm t hick
Demountable partitions used in office build-
that are free to vibrate acoustically independ-
toughened glass sheet will span vert ically
ings are available as a wide range of propri-
Timber stud partitions are constructed
ent of one another.Complicated shapesand
to approximately 2.5 metres (8ft), depend-
etary systems. Partitions can be moved easily
curved partitions are easy t o construct . Stud
ing upon intended use. Glass sheets are set
with a minimum of disruption t o the building
partitions can also be made in metal.These
with a vertical gap of approximately IOmm
in use. Manufactured demountable panels are
are used in conjunction with an internal lining
(3/8in) betw een them which is filled wit h a
often easily integrated with other systems
board, such as plasterboard, and as an alter-
translucent or transparent silicone seal.The
for suspended ceilings and raised floors, to
native to timber. Metal studs are made from
glass is secured top and bott om in small steel
which they are usually fixed.W here a parti-
cold-formed galvanised steel sections.
channels or steel angles set back to back.The
tion forms part of a fire break or smoke bar-
channel or angle fixings are recessed into
rier, the voids above and below the partition,
the floor and ceiling in order to provide an
within the floor and ceiling zone, are sealed
MCH
72
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Horizontal elevation
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MC H
73
a
Materials I Internal walls 2: plaster systems
Plastered walls provide a smooth, continuous
appropriate mixes for different applications.
is expected.The plaster is then continued
finish that is usually painted. Plastering is a
All plasters use either a sand-cement mix. a
across the joint and is keyed into the lath
traditional method that has been adapted for
gypsum plaster(gypsum is a naturally occur-
where a different plaster mix. called isolat-
use on different wall backgrounds.An advan-
ring mineral) or a lightweight plaster made
ing plaster, is sometimes used. Shadow gaps
tage of plaster is that complex shapes and
from minerals such as perlite or vermiculite.
are often formed wit h galvanized steel trims
edges can be formed. Dry pre-mixed plaster
Plasters are usually applied in two coats, as
to createa crisp line between the different
in powder form is used, in order to ensure a
an undercoat and finish.The finish coat has
backgrounds.The joint is revealed as a con-
consistency of mix, and is mixed wit h wat er
a finer texture in order to achieve a smooth
tinuous groove down the joint. Both plaster
on site. Plasters are relatively soft and can
surface by using a mix that would not be
and trim may be painted to create a homo-
have slots cut into the material easily for the
strong enough to be used as an undercoat.
geneous appearance.
passage of electrical wiring.This ease of use
Plasters have different levels of surface hard-
makes it a very practical wall finish which
ness. For example. soft plasters might be
ishto a wall or ceiling. Its soft. fibrous nature
Plaster provides a smooth, continuous fin-
can be cut and patched to accommodate
used for exhibition spaceswhere paintings
makes it easy to work and repai r. Plaster
changes throughout the life of a building. Plas-
are frequently moved; acoustic plasters are
is often used as a wet mix to a surface by
tering is a labour-intensive operation that is
used to increase sound insulation.
tro wel as well as manufactured into lining
carried out entirely on site and the quality of
W hen detailing edges, junctionsand
boards that are fixed on site.The method
finish is very much dependantupon the skill
openings in plastered walls.joints are needed
used generally depends on the nature of the
of the individual plasterer. For this reason it is
where there is either a change in background
background surface where boards are pre-
important to ask for sample areas of plaster-
material or a change in structure, such as
ferred for use over uneven surfaces.
ing to be provided on siteto ensure that the
where a wall meets a column.This isto
required quality can be achieved. Like pour-
accommodate thermal and structural move-
plaster on the external surfaces of walls and
ing concrete, plastering is a wet trade. which
ment at the junction between two materi-
soffits.Their characteristics are similar to plas-
involves mixingthe material with water and
als.Thesejunctions are treated either by a
ter.They can also be used in a board form.
allowing it to dry out.This drying process can
hairline joint, which is mostly concealed, or
fixed to a layer of rigid insulation.
slow down other building operations, particu-
by a recessed joint that forms a shadow gap.
larly where construction time is an important
The hairlinejoints use a layer of expanded
for their appearance and suitability for the
factor.
metal lath that is nailed or screwed to the
background. but also for reasons of cost.
Renders perform a similar function to
Plasters and renders are used not only
background and which spansthe joint to
speed of construction and availability of
ferent countries as a result of the availability
form a continuous background.A breather
materials.They are applied either in one.two
of minerals varying between regions. Manu-
membrane is set behindthe metal lath to
or three coats.
facturers should be consultedto advise on
isolate the plasterif structural movement
A wide range of plasters is used in dif-
MCH
74
Properties of plasters and renders
depth for adhesive is 3mm to 6mm ( I18in to
These mater ials have the following proper-
I14in). For a full set mortar bed,it is betw een
t ies:
6mm and 12mm ( I14in to I12in).The joints
sealing the external wall completely. or be
· High resistance to impact damage.
between tiles are filled with a resilient mate-
porous,to allow the wall behind to dry out.
· Easily drilled,filled and repaired.
rial that is compatible with the tile to seal
In common with int ernal tiles,joint widths
· Moderate to low sound absorption.
the gap without shrinking.Large areas of til-
should be a minimum of2mm ( I I 16in).s
· Low resistance to perpetual damp.
ing are divided int o bays 3m t o 5m ( l Oft to
· High fire resistance.
them. Grouting can either be impervious,
16ft) in either direction to compensate for movement in the substrate beneath.joints
Tiling Tiling provides a hard, impervious finish that is resistant to wat er penetration and surface damage and is easy to clean.When the
are aligned with any movement joints in the structure. Movement joints are 5mm to 10mm (31 16in t o 3/8in). Many smaller tiles have spacer lugs that
building fabric has dried out, tiles are fixed t o
assure a narrow, uniform joint. Plain edge tiles
the background surface with cement or pro-
are spaced at least 2mm (I I 16in) apart to
prietary adhesive.joints are grouted.
allow for movement, although wider joint s
Interior wall t iles
tars or grouts are generally cement-based
are used for their visual effect.jointing morGlazed tiles are used for walls, and are made by applying glaze to a fired t ile,then fir-
but an ever-expanding range of products is becoming available.
ing it a second time.The most common glaze used is enamel, avai lable in a wide range of
Exterior wall tiles
colours.There is almost no moisture move-
Glazed wall t iles for external use must
ment or thermal expansion of most glazed
be frost proof, and adequately resist airborne
tiles.
pollut ants, scratching and fading caused by
Tiles are fixed t o a background of
UV light.Tiles are fixed with an exterior
cement render or gypsum plaster once it has
qualit y adhesive.The bedding and grouting
dried out;typically the drying out takes up
must be weather- and wat er-resistant. Bed-
to four weeks. Mostly proprietary adhesives
ding depth is 3mm to 6mm ( I18in t o 1/4in).
are used t o fix the tiles, although occasionally
Movement joints must coincide with those
sand-cement mortars are used.The bedding
of the background wall and must not bridge
MC H
75
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Horizontal elevat ion
Horizontal elevation
iValiboard systems usegypsum plasterboard
skim is to usetapered edge plasterboard
heet to give a plastered wall finish to a vari-
sheets to allow joints to be covered wit h
..:ty of backgrounds.A thin skim coat finish
paper tape and filled in order to avoid crack-
over the plasterboard provides a continu-
ing.The wall is then coated to provide a sur-
ous, dry fixed partition system that is fastto
face ready for applied finishes such as paint-
build. it is particularly useful on timber- or
ing.This almost 'dr y' process allows following
metal-framed partitions where its use avoids
trades to start work sooner than with plaster.
the need for the more expensive traditional
which requires much longerto dry.
technique of plaster and lath.An alternative
15
Ho rizontal elevation
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use of dry lining isto fix plasterboard sheets
assembled on site and can be easily modified
backto a masonry wall using either steel or
either during or after construction. It is dif-
timber battens which are screwed back to
ficult to re-use plasterboard sheets although
the background wall, or alternatively on pIas-
the studs can be recycled.W allboard covered
ter dabs which are literally dabs of plaster. A
partitions often perform better acoustically
variety of gypsum plasterboard types is used;
than an equivalent blockwork partition. Parti-
glass-fibre reinforced boards can be curved
tions can be formed using three or more lay-
to form radiused corners. High-impact resist-
ers of plasterboard sheetwithout the use of
ant boards are used where a hardwearing
studs to a maximum height of approximately
plasterfinish is required, and fire-resistant
three metres (lOft).
boards are used in fire protection, particularly to structural steel frames. Wallboard systems are finished with
MCH
76
Wallboard covered stud partitions are
Timber stud partitions are limited to around 35 metres (11ft 8in) in height, since cut timber sections of greater length are
either a 2 to 3mm (1 /16 to 3/32 in) thick
more difficultto obtain and are expensive.
skim coat or a full ISmm (9/ 16in) plaster
Metal studs provide most flexibility in terms
coat.in practice,the full plastercoat is not
of partition thickness and height, spanning up
often used except, for example, on curved
to around eight metres (26ft 8in) without
dry liningpartitions in order to provide a
need for intermediary support.W ith longer
very smooth finish.An alternative to a full
spans, partition thickness can be reduced
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Horizontal elevation
Vertical section
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to around ISOmm (6in) by setting studs at
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closer centres, typically 300mm (I ft) and by changing the stud type. Short vertical
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Horizontal elevation
spans, up to around 3 metres (lOft) use cold formed pressed steel channel sections, while longer spans up to approximately 5 metres (16ft8in) use the same channels set face to face to form a box section, while spans up to 8 metres (26ft) use cold formed back-to-
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Details I. Movement joint 2. Quilt insulation 3.Top rail in timber or metal (pressed steel shown) 4. Ceiling level 5. Plasterboard 6. Softwood skirting 7. Pressed steel bottom rail 8. Plasterboard 9. Floor level 10.Stud in timber or metal (pressed steel shown) I I. Two layers plasterboard/drywall 12. Plasterboard/drywall laps adjacent run of partition 13. Plasterboard/drywall butt jointed at edge 14.Wall in different material (concrete block shown)
back channels that form an I-section.These studs are also available in varying depths to
15.Plasterboard/drywall on battens or dabs 16.Internal timber door frame 17.Insulated board 18. Mineral quilt providing acoustic insulation 19. Plasterboard/drywall butt jointed at internal angle 20. Door leaf 2 I . Arch itrave 22. Packer
provide different overall partition thicknesses to accommodate the layering of sheets for varying amounts of stiffness, fire resistance and acoustic performance. In common with plastered walls, expansion joints are required where there is a change in construction in order to accom-
Q3)
Horizontal elevation
modate thermal or structural movement at the junction of two different backgrounds. This typically occurs at the junction of a partition and a structural column. Junctions can be continuous if constructed using a latexbased plaster.Alternatively, a shadow gap is formed which uses galvanized steel trims to create the shape of the joint in a way that imitates a plaster recessed joint.
Horizontal elevation
MCH
77
Materials 0 I Floors Details I.Timber flooring block 2.Timber boards 3.Timber battens 4.Ceramic tile 5. Stone 6. Compressible seal 7. Compressible backing 8. Stainless steel angle 9. Bedding compound IO.Concrete floor
Fixed floor finishes are those which are not
is provided by rubber-based compounds
wit h slab sizes adjusted to allow it to be car-
intendedto be accessible or demountable
which are used in indoor sports facilities,
ried by hand and laid in place.A common
and form a permanent part of the building.
but they have less abrasion resistance. Both
size is a module of SOOxSOOmm (20x20in)
Floor finishes are usually harder and more
epoxy and latex coatings,together with varia-
or 600x600mm (2ftx2ft) slabs, which allows
resilient than the floor structure, or substrate,
tions such as polyester resins, are referred to
IOmm for the joint between them. For small
beneath. Since the properties of finishes and
as poured floor finishes due to their ability to
applications, stone can be ordered from
substrates are usually different, the finish used
be poured in place to provide a self-levelling
choosing a sample, but for large areas, the
must be laid in a waythat allows both it and
joint-free floor finish.They are poured over
material is cut to order andthe architect
the substrate to move together or be sepa-
large floor areas to produce thicknesses of
should visit the quarry to choose the mate-
rated in order to avoid cracking in the floor
up to 6mm (1 /4 in). Made by mixing a resin
rial. In common with other natural materials,
finish. W here there are movement joints in
with a curingagent, they provide a hard,
it is difficultto define precise visual quali-
the floor structure,the floor finish is usually
smooth finish which can be coloured and is
ties since its natural formation produces an
broken to allow expansion and contraction.
resistant to chemical attack.
enormous variety of appearance .The usual
As a result, the finish can influence the design
Terrazzo is a hardwearing floor finish
of the substrate. For example, a cast-in-place
that is applied to a concrete substrate. It
between the most and least marked, andthe
concrete slab may require contraction joints
consists of crushed marble aggregate mixed
lightest and darkestin a set of sample slabs.
at centres which do not correspond to the
wit h cement.The material is applied as wet
Because stone has little strength in tension,
module of a proposed tiling layout but which
mix to a thickness of between IS and 2Smm
the substrate must be firm, with very little
should be adjusted to suit the design of the
(S/8in to Iin) depending on whether it is
structural movement or deflection.
floor finish.
bonded directly to the screed or concrete
Stone floors are ground before being
slab beneath.Terrazzo is bonded by laying it
laidto provide different surface finishes.They
on the concrete substrate while it is curing
can be polished, using fine sanding wheels, or
(but hard enough to walk on). It is laid in bays
honed, using rougher grinding wheels. Floor
floor slab, with its surface sometimes polished
formed by movement joints (expansion and
sealers are often not recommended for
to provide a smooth,dust-free finish, either
contraction joints) in the concrete substrate.
some stones since some slabs will be more
as a screed or as a power-floated finish to a
The bays are separated by stainless steel,
absorbent than others, resulting in exagger-
floor deck. Grains of carborundum can be
brass or bronze angles in a very similar way
ated colour differences across a floor surface.
addedto improve the wear of the floor. Con-
to ceramic tiles.Terrazzo is finished by grind-
cret e floors can be coated wit h floor paints
ing and polishing.
Concrete Concrete can be used as a self-finish to a
which have improved enormously in recent years to provide fairly hardwearing surfaces that will lastup to S years but are not suit-
method is to define 'extremes' of quality
Timber Timber flooring can be used as a floor
Stone Stone is used as a fixed floor finish in the
finish on concrete, timber or cold-formed steel framed floors. In all three instances, the
able for very heavy usewhich can causethe
form of paving slabs that are bedded in a
substrate is sealed with a vapour barrier to
paint to wear away quickly. An epoxy coat-
sand-cement screed and can be used both
avoid the timber rotting.The timber is either
ing is used where a harder surface finish is
internally and externally.The thickness used
loose-laid as solid strip flooring, fixed on
needed for heavy foot traffic,particularly for
depends on the strength andthickness of the
bearers resting on the substrate, or bedded
industrial applications.This polymer coating
stone andthe size to which the stone can
in mastic or bitumen as block flooring. Strip
has excellent resistance to abrasion but is a
practically be cut from blocks.The most com-
flooring has traditionally been used with tim-
very hard surface to walk on.A softer surface
mon thickness is 20-30mm ( Iin to I 1/2in)
ber strips less than IOOmm (4") wide, while
MCH
78
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Vertical section are available in a wide range of colours,the
a much greater range of void depth, ranging
of around 150mm (6"). Nowadays strip floor-
latter are produced only in their natural col-
from 100mm (4in) to around 2000mm (6ft).
ing refers to all sizes of hardwood tongued
ours of reds,browns and blues.
Semi-accessible types are restricted to low
boards indicate anything wider up to a limit
and grooved board.Thicknesses range from 9
Floor tiles are made in many sizes and
floor voids of around 150mm (6in).The fully
to 38mm( 3/8in to I I/2in).Almostall types
thicknesses.They are laid either on a bed of
accessible types are generally steel composite
are proprietary systems that are either fixed
sand-cement mix or adhesive. Each bay of
panels with a concrete-based infill, supported
to supporting battens as a sprung floo r; typi-
tiles is edged with a 6mm ( I/4in) wide move-
on variable height pedestals. Semi-accessible
cally used in sports halls, or are held together
ment joint, which can be fi lled with a flexible
types are generally made from timber com-
by pressed steel clips as a continuous mate-
seal, such as polysulphide. Maximum bay size
posite panels supported on concrete pads or
rialthat rests on the substrate. Beech and
is usually six metres x six metres (20 x 20 ft).
timber battens.The two types have varying
maple are the most common hardwoods
The bay size depends on whether the area
degrees of rigidity in their framework to suit
used,which have a light coloured appearance.
is reached by sunlight and/or moisture. Metal
the degree of accessibility required. In some
A gap between the floorand the wall is left
edging strips,or a rigid sealant suchas epoxy-
systems, structural stability of the frame is
to accommodate movement in the wood due
polysulphide, is used to protect bay edges in
lost if too many modulesare removed for
to changes in temperature and humidity.This
large areas of tiling.
maintenance access. Fully accessible floo rs are made with a
gap is typically 10mm (3/8in) for a four metre (13ft) wide bay of stripflooring. Wood block flooring consists of small
Raised Floors Raised floors were first used as computer
variety of construction methods. Some are made as a support framework with legs
hardwood blocks that are bonded with bitu-
floors to provide a zone for electrical cables
beneath.The panels fit intothe frame to be
men to a concrete floor. Block sizes vary
and air handling ducts to large computers
supported on all four sides. Others have
from 25 to 100mm (I to 4 in) wide and 150
housed in a separate room.They are now
self-supporting panels supported on an
to 300mm (6 to 12 in) long. Depths vary
used throughout office buildings as a means
adjustable leg in each corner. Semi-accessible
from 19 to 38mm (3/4 to I I/2in).Blocks
of providing a zone for mechanical and elec-
systems vary even further in their design.
are bonded directly to the concrete with a
trical services including ventilation, as either
Some comprise a single precast concrete tray
bitumen-latex adhesive. Simple rectangular
a complement or replacement for those
with integral legs.These are laid side by side
patterns or herringbone patterns are the
used in suspended ceilings. Raised floors are
directly onto the floor slab. Others are very
most common ways of laying blocks. Both
used as a method of bringing electrical cables
similar to the timber sprung floors used in
strip flooring and blockfloo ring require a
under the floo r to a large number of points
sports halls, consisting of a rectilinear grid of
surface seal, such as polyurethane sealer; to
while allowing tiles to be moved to accom-
softwood battens resting on acoustic pads to
avoid dirt being trodden into the grain. This is
modate changing servicing requirements.
prevent sound transmission.Timber compos-
re-applied every few years depending on the
Completely open voids can also be used as
ite boards are screwed down to the frame.
amount of wear experienced by the floor.
an air plenum to supply or extract air in a mechanical ventilation system.
Floor ti les
Raised floors are manufactured as propri-
Ventilation grilles and electrical socket boxes can be incorporated into all types. Floors typically have carpet tiles loose laid on
etary systems with different loading capabili-
to p,to provide both a comfortable walking
these are ceramic and quarry tiles. Ceramic
ties, designed to be either fully accessible or
surface and for acoustic purposes. Carpet
tiles are manufactured from refined clays,
semi-accessible, depending on the ease of
can be separately bonded to each tile or be
There are two types of tiles for flooring;
while quarry tiles are made by extruding or
use and frequency of access required to the
loose laid offthe grid to conceal joints in the
pressing natural clays. Whereas the former
floor void beneath. Fully accessible types have
floor beneath.
MCH
79
Materials 0 I Ceilings Details I. Plasterboard/dr ywa ll 2. Fixing rails 3. Suspension rod, w ire or pr essed metal strip 4. Clip t o secure panel 5. Ceiling panel (perforated met al panel w it h acoustic lining show n)
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Suspended ceilings are used primarily to
floor structure,Access hatches can be used
directly on the section, creating an exposed
provide a service void between a ceiling
but are difficult t o conceal. Fixed suspended
grid, or is set hanging partially below the
plane and the underside (soffit) of the struc-
ceilings can be used to form single direction
frame in a semi-concealed grid.The spring
tural slab above.This zone is usedto house
curves by bending plasterboard around a
clip system allows the tile to be slotte d into
recessed light fittings, ducts for mechanical
modelled frame,
the support grid from beneath in a con-
vent ilat ion and associated equipment.There
Complex shapes can be formed with
cealed system.The support grid can also be
are two generic types of suspended ceiling,
metal laths, Fibrous plaster is often used,
concealed by fixing the tile onto aT-section
The fixed version is used where a continu-
which provides a smooth surface that is
grid from beneath.This is done where
ous plastered surface is required and where
easy to work but lacks the strength of other
aluminium or steel sheet is countersunk
there is no need to access the ceiling void
plasters.As a result, it is applied onto a rein-
screwed to the support frame, Noise control
from below,Accessible types are used prima-
forcing mesh in a very similar wayto ferro-
within a room, or between adjacent spaces,
rily in office buildings where they integrate
cement. Fibrous plasteris usedwhere curves
is achieved by setting a sound-absorbent
with a modular layout of partitions,They are
in tw o directions are required as well as in
board or quilt onto the upper face of the
designed to suit both cellularoffice layouts
repetitive decoration, where items can be
ceiling tiles.The tiles are usually perforated to
and open office areas requiring individual
made in a workshop and later fixed to the
allow sound to pass through to the insulation
lighting and mechanical vent ilat ion,
ceiling,
behind,
Fixed suspended ceilings consistof either
Accessible ceilings use a support ing grid
The most common support grids are the
layers of plasterboard sheets or wet-applied
in steel or aluminium.The two most com-
one-way grid andthe two-way grid.The one-
plasteron metal laths which are supported
monly used types are the T-section and the
way system has identical sections set parallel,
on a frame suspended from the soffit of a
spring clip. Both are designed to be as light
at centres corresponding to the width of the
structural slab or floor on either wires or
as possible with varying degrees of strength
tiles.Tiles are supported on tw o sides and
galvanized steel strips,They can be designed
and rigidity, which are defined by the loads
span between the sections of the grid.Parti-
as a simple timber or metal supportin g frame
imposed on the ceiling by services from
tions beneath can be supported cont inuously
or be specified as proprietary manufacturers'
above and by partitions fixed to it from
in one direction but are supported only at
systems,
beneath, In some manufacturers' systems,
points in the other direction,The reduced
dimensional stability of the frame is lost if
flexibility makes the system economical.A
ous soffit for recessed lighting, and a ceiling
Fixed ceilings create a smooth,continu-
too many tiles are removed during mainte-
two-way system uses either metal cross tees
plenum for ducts that do not require access,
nance access.TheT-section uses an inverted
that span between the main runners or by
They can also provide a fire-resistive layer
T-shaped aluminium extrusion which holds
using the same sections set perpendicular to
where this is not provided by the supporting
the ceilingtile in place,The tile either sits
one another to creat e a full grid.The latter
MCH
80
Details o
I. Plasterboard/drywall 2. Fixing rails 3. Suspension rod, wire or pressed metal strip 4. Clip to secure panel 5. Ceilingpanel (perforated metal panel with acoustic liningshown)
Vertical section
type is made by half-jointing the main run-
ibility of the two-way system makes it more expensive.The frame is fixed back to the soffit with members of varying rigidity: wires,
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rods and angles. Suspension wires are not usually appropriate if partitions are fixed in such a way as to exert pressure from below. Like their supporting grids, ceiling tiles
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are designed to be lightweight.The most economical generic tile is mineral fibreboard, which provides high acoustic insulation but is limited to smaller spans due to its lack of rigidity. Greater thicknesses of board add considerably to the weight of the ceiling.The typical grid size in this material is 600x600mm (2ft x 2ft). Larger tiles are made from perforated steel trays. Since steel is a poor absorber of sound, it is perforated to enhance its acoustic performance, and in addition can be lined on the upper face of panels with either thin mineral quilt or an acoustic pad. Ceiling grids up to around 2000x3000mm (6ft 6in x 9ft lOin) are possible.Aluminium sheet can also be used but it requires a greater depth of vertical edging to attain the spanning capability of steel.This increases the overall depth of the ceiling.
MCH
81
WALLS
Trends in facade design Generic wall types Metal I Sheet metal 2 Profiled cladding 3 Composite panels 4 Rainscreens 5 Mesh screens 6 Louvre screens Glass systems I Stick systems 2 Unitised glazing 3 Clamped glazing 4 Bolt fixed glazing 5 Glass blocks and channels 6 Steel windows 7 Aluminium windows 8 Timber windows Concrete I Cast in-situ 2 Storey height precast 3 Small precast panels Masonry loadbearing walls Masonry cavity walls I Brick 2 Stone Masonry cladding Masonry rainscreens Plastic Plastic-based cladding I Plastic rainscreens 2 Timber I Timber frame Cladding panels 2
MCH
83
ails 02 Trends in facade desig_n
_
Significant changes in the design of external
the expression of structure in buildings has
construction.Thermal bridges are avoided
walls in recent years have increased thermal
been replaced by an interest in energy con-
by providing a separating component in a
performance and solar control , great er wat er
servation.This is largely because the effect of
low conductivity mater ial,called a 'thermal
t ightness and a reduction in air infiltration
additional layers of external insulatio n.blinds,
break', that prevents heat or cold from being
ratesthrough wall assemblies, and a limit ed
shading and so on often renders the struc-
transmitted between inside and outside.An
return to natural vent ilation where possible
ture almost invisible.
example of it s use is in glazed walling, where
as a parti al alternative to mechanical ventilation in larger scale buildings.These changes
the construction of a frame of mullions and
Thermal insulati on
transoms requires some continuity of metal
The useof thermal insulation has
from outside to inside. Plastic spacers of low
the late I980s, the increased use of ther-
increased dramatically during the past 15
thermal conductivity are posit ioned to pro-
mal insulation brought with it an increased
years with wall assemblies achieving a U-val-
vide a thermal breakthat also enhances the
risk of condensation occurring in cladding
ue of 0.25W /m2K as a minimum standard.
structural integrity of the construction.
assemblies.This condensation can occur both
This compares with a typical level of 0.6WI
have led to a shift in design priorities. During
Two generic types of thermal insula-
inside the panel and on the inner face of wall
m2K in the early I980s.There is an accom-
tion have emerged for use in wall systems:
assemblies.The avoidance of condensation
panying risk of interstitial condensation
rigid foam and fiexible quilt types.The rigid
has been the result of technical development
occurring within a wall assembly from damp
foam type is made typically from either a
since.The increased use of natural ventila-
air that penetrat es a wall assembly where it
polymer-based board such as polyurethane
tion, both as air supply and as a means of
may condense and cause damage. In additio n
foam. Since both are non-hygroscopic or
cooling buildings at night has had an effect
to dew point calculations undertaken at the
'closed cell',they can be used in sit uations
on cladding design. part icularly in the integra-
design stage t o assess risk,vapour barriers
where the thermal insulation can become
tion of opening lights and louvered slots in
are added to halt the passage of damp air
wet without any significantreduction in its
panels.The arrival ofthe deep plan building.
into wall assemblies where interstitial con-
perfonmance. Closed cell insulation is also
with distances of up t o 18 metres between
densation can occur; typically on the warm
used to form the structural core of metal-
external walls has led to a need for greater
(in winter) side of the insulation.Alternative-
faced composite panels as well as in facing
levels of daylight entering a building.This. in
ly.the internal construction can be venti lated
the inner leafof cavity walls. In contrast.
turn,has increased the need for both solar
in order to draw away damp air.
fiexible quilt is made typically from a mineral
shadingand glare control. In addit ion,the
Condensation can also occur on the
fibre quilt, cut t o fit voids in panel frames
cost of photovolt aic cells. which can gener-
inner face of a wall in temperate climates,
more easily than board but it s lack of rigidity
ate electricity when exposed to sunlight,
typically where there is continuity in a mate-
makes it unsuitable for use externally. W hile
has reduced considerably over the past
rial from the outside to the inside of a build-
heavier insulation helps to provide a more
15 years.As a result, they are increasingly
ingthat allows a direct passage of heat or
rigid, wat er resistant material,the lighter; less
used in large-scale applications for buildings.
cold through the external envelope.W hen
rigid types provide better thermal insulation.
These energy-led changes in wall design
th is 'thermal bridging' occurs,condensation
As a result,the choice of core is a balance
have generated a range of t echnical develop-
can form on the inner face of the wall where
betw een the needs of rigidity and thermal
ments, which have changed the emphasis of
it can drip down, resulting in inconven-
performance.
facade design.The architectural interest in
ience to building users and damage to the
MC H
84
Rainscreens Rainscreen cladding is a development of
between the outside of the wall and the inside will allow small amounts of rainwater
Use of materials in facade systems The different material systems for
the rainscreen for pressure-equalised walls
to penetrate the outer seal.This effect can
facades are very much infiuenced by the
researched during the 1960s. It was found
be countered through two means;the water
particular material chosen.The essential
that water commonly penetrates joints in
can be drained away within the metal fram-
issues in working with each material in
walling because of the outside air pres-
ing that supports the cladding panels,and
facade assemblies are described in the fol-
sure being greater than that inside the joint.
the pressure differences can be equalised
lowing paragraphs.
Water arriving by a variety of means, mainly
by ventilating the system by providing slots
gravity,wind and capillary action, was able
at drainage points, usually set at the base
to penetrate the outer seals of joints.The
of the wall.This ensures that water is not
introduction of rainscreen framing systems
trapped within the panel framing, nor is the
mainly on sheets,extrusions and castings.
and panel systems overcame this problem by
water discharged at vulnerable points in the
Thin sheet metal is made in narrow strips
creating an outer 'screen' layer or seal that
construction where staining and damage can
up to IOOOmm wide, making it necessary
stops most of the water entering the joint,
occur on the face of the panel.The use of
to form simple, reliable joints at close cen-
but ensuring that the air pressure in the void
ventilation within an assembly, on the exter-
tres when joining the material together to
behind the panel or joint is the same as that
nal side of a thermal insulation layer, allows
form a weather tight surface.This is done
outside it. Rainscreen systems have three
cladding systems to dry out once water has
by folding the metal together at the edges
essential functions:
Metals Metals used in facade systems are based
penetrated. Where water or water vapour
to form a continuous seam that projects
- To protect joints in the cladding assem-
penetrates a material in a wall or roof it
from the wall surface, making it difficult for
bly from the worst effects of windblown rain.
is stopped from travelling further by the
water to penetrate from outside. Standing
vapour barrier or waterproof membrane. At
seams are economic to make, but need to
waterproofing system whose appearance is
this point, it can be difficult for the water to
be done with care to avoid uneven joint
not suitable for an external wall.The same
dry out. A void is sometimes formed at the
lines. Because it is difficult to achieve crisp
principle applies to roof cladding.
vapour barrier to allow the water to evapo-
lines with this method, which relies on site-
rate and prevent the adjacent material from
based workmanship rather than the use of
thermal insulation fixed on the external face
being damaged.This is particularly important
workshop-based machines,the uneven 'oil
of a high thermal mass construction such as
in the case of timber, where eventual rot can
canning' appearance can be accepted as an
concrete.
occur.The development of drained systems
uneven texture forming part of the design.
accepts that externally applied seals will leak
Because sheet metal used in facades is thin
small amounts of water and that it is better
in order to fold it and work it, it requires
- To provide a decorative screen for a
- To provide an outer protective layer to
Drained and ventilated systems There has been a move away from 'her-
to design for that eventuality. Even systems
support from underneath.The support sur-
metically' sealed systems,which rely entirely
with a single outer seal can be designed to
face conveniently forms a base for a backing
on a single weatherproof outer skin,towards
drain away water within their construction.
waterproof layer which is needed behind
'drained' systems.This is common to virtu-
sheet metal since it is unable to exclude
ally all sealed facade types. Drained systems
rainwater. Sheet metal can be welded
accept that the air pressure differences
together to form a continuous waterproof
MCH
85
Walls 02 Trends in facade design
sheet material, but thermal expansion needs
watert ightness and durability of metal.The
higher thanthe outside atmospheric pres-
to be allowed for with standing seam joints
successful bonding of rigid insulation to th in
sure, drawing water into the frame and
that prevent the material from deforming as
metal has been essential to the success of
potentially causing leaks.The problem of
t he metal expands.
composit e metal panels.These panels are
capillary action has been overcome, not by
joined with tongue-and-groove joint s, usually
increasing the pressure on the seal between
reduced by increasing the size of the metal
on two sides.While this is a reliable joint,
frame and glass, but by ventilat ing the void
sheet being used. Profiled metal sheet can
the joint on the opposite two sides is usu-
inside the frame so that any water that pen-
be formed in very long lengths, and in widths
ally less accomplished, normally being a butt
etratesthe outer seal is drained away safely
The number of joints on a facade can be
up to around ISOOmm.Joints between
joint sealed with silicone, wit h an additional
down the cavity to the outside.The drained
sheets are formed by lapping sheets both
to p hat metal profile to enhance the seal.
and ventilated cavity provides a second line
horizont ally and verticallywith sealant set
Four sided tongue-and-groove jointed panels
of defence against rainwater penetrat ion
between adjacent sheets to provide a water-
are more difficult to fix and more difficult to
through the outer seal.The principle of pres-
proof joint.This allows the sheet material
remove if damaged.The tongue-and-groove
sure equalisat ion, with an inner chamber
to span between the support s of a framed
joint incorporates a void in the centre that
behind an outer seal is essential to current
support ing structure behind, rather than
allows water t o drain down.The basic prin-
framed glazing systems.An alternative meth-
needing continuous support. Fixing profiled
ciple wit h sealing joints betw een composite
od of glazing is t o avoid a frame entirely in
sheet t o the supporting structure requires
panels is to ensure that any water entering
order to increase the effect of transparency
fixings that penetrate through the outside
the joint will drain down an internal cavity
given by the glass. In point fixed glazing,the
of the sheet t o the inside, which presents a
that drains water away t o the outside at the
glass is held at only at a few points by small
potentially weak point for waterproofing. This
bott om of the panels.
brackets or bolts. Glass is clamped together with plates, and bolted together through the
penet ration through the material by fixings is avoided in standing seam sheet metal. Fix-
Glass
joints between the glass.Alternatively, holes
ings for profiled sheet are made to be fixed
Glass in facades is supported either by
easily, using a self-t apping screw,which has a
edge frames or by fixing it at points. Glass
held by bolts secured directly through the
waterproof washer on the outside and a drill
facades are beginning to be glued together
holes in the glass without plates, using discs
bit on the front of the screw to make a hole.
without any metal fixings but the design of
or a countersunk profile to the bolt connec-
The self-tapping sealed screw is essential t o
such structures is in its early stages. Frames
t or.Joints are sealed with silicone in a single
the success of profiled metal sheeting, and
supporting the glass must both hold the
line of defence.W hile the material does
corner tri ms and folded copings in the same
glass in place and prevent rainwater from
not suffer problems of water being drawn
material ensure the watert ightness of junc-
penetrating the seals. Difficulties in providing
through it as with clamped rubber seals,
tio ns.
reliable rubber-based seals have led to the
good workmanship is essential to the suc-
'pressure equalised' or 'drained and vent i-
cess of these single seals.
Sheet metal has been developed in
are drilled in the glass and the sheet s are
recent years to be bonded to closed cell
lated' frames discussed earlier in this section.
insulation, since both materials are used very
Water penetration in frames has tradition-
ed by bonding the blockstogether with
economically in combination, so that the
ally been caused by capillary action where
either a cement-based mortar or silicone.
stiffness of insulation is combined with the
the air pressure inside the frame becomes
Because blocks are set with continuous
MCH
86
W alls built in glass blocks are construct-
vertical and horizontal joints giving them
up complex shapes and textures which
their characteristic appearance, panels are
would be much harder to form vertically.
Horizontal joints have to accommodate
structurally inherently weak, and this is dealt
Ferro-cement is capable of a high degree
deflections and movement from the sup-
with by introducing steel or aluminium rein-
of surface modelling, being made as a
porting structure if the panels are supported
forcing strips or rods into both vertical and
cement mortar-based mix with a high
from floor slabs, as is usually the case due
horizontal joints as reinforcement. However,
proportion of steel reinforcement. This
to their self-weight.Vertical joints are usually
this limits glass block panel sizes to modest
material ensures very smooth finishes, but
required to be thinner in order to exclude
dimensions when compared to other glass
is more commonly used for yacht hulls.
rainwater. The visual balance of joint widths,
wall systems.The principle of stack bonding
In-situ cast concrete is a monolithic
verticality and horizontally across the facade.
although a seemingly small issue,is critical to
limits panel sizes but is usually overcome by
material that provides an almost continu-
the visual success of precast panels. Notching
making the supporting structure lightweight
ous waterproof surface. Rainwater pen-
and grooves are introduced around open-
yet rigid in order to minimise its visual effect.
etrates only a few centimetres into the
ings to ensure that windows and doors can
More heavyweight supporting structures
depth of the material, but in temperate
be inserted in a way that provides weather
make the blocks appear more like individual
climates this leads to visible surface stain-
protection as well as concealing part of the
panels set into a visual grid.
ing.This can be overcome by colouring
frame to avoid visible seals around the edge
the concrete, adding textures, or ensuring
of the openings. Highly visible seals can also
that rainwater does not wash off surfaces
lead to very disappointing visual results.
Concrete An essential aspect of concrete is that
where dirt can collect, which would
Masonry
it is a material formed in a mould, leaving a
cause staining on an area of wall beneath.
surface finish which is the mirror image of
Movement joints with in-situ concrete
that mould, or formwork. Consequently, an
require careful attention so that they are
concrete block have the advantage of being
Loadbearing walls in brick, stone and
important aspect of concrete detailing is to
waterproof but do not leave strong lines
able to avoid the visible movement joints
understand how formwork and moulds are
that are at odds with the overall concept
associated with non-Ioadbearing cladding,
fitted together. Formwork can be made to
of the facade.The facade designer must
which can enhance the massive visual quality
almost any shape, from plywood or GRP
always be aware of where joints occur
of traditionally built walls.An essential issue
(glass reinforced polyester), though specially-
and how wide they will be in order to
in loadbearing construction is to ensure that
made formwork can be expensive to make.
avoid disappointment during construction.
the wall is sufficiently thick to avoid rain-
Joints between formwork panels are visible
Precast concrete panels are jointed
water penetration as well as being able to
in the finished concrete, and if this is not
with pressure equalised drainage cham-
provide thermal insulation either in the wall
to be overclad with another material, then
bers behind vertical joints, which drain
construction or on the inner face.The sealing of windows and doors into openings follows
joints need to be arranged to suit the archi-
out of horizontal joints. Like in-situ cast
tectural concept for the facades. Complex
concrete, the general areas of concrete
principles of reinforced concrete discussed in
shapes for facade panels can be made more
are waterproof, but the joints require
the previous paragraph.
easily in precast concrete where, in a work-
careful attention to avoid their becom-
In masonry cavity walls, two masonry
shop, concrete is poured into a mould which
ing too wide as a result of wanting to
skins are tied together to form a single wall,
is laid flat, making it much easier to take
achieve a consistent joint width both
and here the detailing of openings in walls
MCH
87
al sOL Trends in facade design
is undergoing continual refinement in order
t ively mitring the junction between the two
panels. Most types are available as proprie-
to reduce thermal bridges.The top of an
stones. Since the thickness of stone cladding
tary systems, with manufacturers havingtheir
opening is support ed with a lintel that both
is seen only at external corners, the choice
own details for window openings, parapets, cills and corners.
closes the opening and ties the two skins
of revealing or concealing its actual thick-
together while forming as small a thermal
ness, rather than the massive stone quality
bridge as possible. Proprietary cavity clos-
the facade may aim to convey.Thin sto ne
material often has up to five layers within
ers and insulated lintels are used but these
cladding is often used for its surface texture
the material that provides a high level of
tend to match the shorter lifecycle of the
rather than conveying an idea of massive-
thermal insulation. Some manufacturers use
windows rather than that of the supporting
ness.The choice of easily commercially
thermally broken sections, but the more
structure, which is usually longer. Providing a
available stones has increased dramatically
visually appealing sections have no thermal
continuity between the thermal insulation in
in recent years, widening the choiceto thin-
breaks. Since these sections are made from
the cavity. fixed to the inner skin in the case
ner sandstones and limestones which have
aluminium extrusions,the opportunity exists
of blockwork or masonry units, can lead to
physical properties closerto those of weak
continually to improve the system in con-
wide joints around windows, which needs
granites. Masonry rainscreens are a recent
junction with manufacturers.An essential
careful attention to avoid visual clumsiness.
development and comprise extruded ter-
aspectof working with proprietary systems
This issue is easier to resolve if the thermal
racotta panels that are fixed in a variety of
is that some have standard window and
insulation forms part of the inner skin as is
ways depending on their size. Since they are
door sections which have an appearance
the case with inner skins in timber framing
completely independent of backing walls
that may not suit other design approaches.
or light gauge steel frames.
they present enormous freedom in design.
The challenge here is to be able to modify the windows, doors andtrim s to suitthe
In stone cladding, panels are mortared together and supported on fixings at each
W hen polycarbonate sheet is used,the
Plastics
overall design for the facade. Other polycar-
floor level, where each stone is individu-
Plastic-based cladding achieved a certain
ally restrained backto an inner wall that
popularity in the 1960s and I970s, present-
for windows and doors and usually have
bonate sheetsystems have little provision
provides lateral restraint from wind loads.
inga fresh approach in building construc-
no standard method of interacting with
W indows and doors typically are fixed
tion based on lightness in weight and a
the support ing structure.These have to be
to, and supported by,the inner wall.The
craft-basedworking method in economic
developed with the manufacturer to suit
gap between the outer thin stone and the
materials that appealed to designers. Since
a particular design. Because polycarbonate
windows fixed to the inner walls is usually
then its use has been more modest, with
is used for its qualities of transparency and
achieved by either putting a trim around the
concerns about durability and colour fading,
translucency. the supporting framework
reveal in the same material as the window
which have largely been overcome in the
is very visible,even with translucent wall
(usually metal) or by adding stone panels
plastic-based materials available today Sealed
panels, so trim s to support framing should
around the opening.W hen stone panels are
plastic-based cladding uses mainly polycar-
be designed as carefully as those for glazed
used around the openingthere is always a
bonate and GRP sheet that is either fixed
curtain walling. In common with glazed walls,
choiceof either revealing the edge of the
into frames generally used for glazed curtain
polycarbonate panels can be either fixed into
stone of the reveal trim (or the edge of the
walling, or is fixed together as self-supporting
frames or be fixed at points wit h bolts and
adjacent stone in the facade) , or alterna-
panels in a way similar to metal composite
brackets. Silicone-based sealants are com-
MCH
88
monly used to seal between panels in the manner of bolt fixed glazing. GRP panels are also fixed into glazing
language of timber joints. Although timber can be used as both
can also support fiy screens,awnings and related metal attachments to window and
cladding panels and as rainscreen panels
door openings.Timber wall construction
systems, but can be fixed together as sealed
over a different background wall, the timber
is relatively thin, at around 150mm overall,
cladding units with pre-formed stand-
boards in both cases are set clear of the
compared to 300mm for concrete and
ing seams like some proprietary systems
backing wall to ensure that both sides are
masonry-based facades, resulting in smaller
for profiled metal sheet.They can also be
well ventilated. When timber boards are
window reveals which are easy to detail with
formed into fiat rainscreen panels with visi-
used to clad a platform frame, the same gen-
modest trims and cills.Window frames are
ble or concealed fixings.An important aspect
eral principles apply as for the construction
sometimes set on the outside face of the
of detailing in this material is its relatively
of individual timber cladding panels,except
wall to reduce any risk of rainwater penetra-
high thermal expansion which leads to larger
for the vertical joints. Vertical joints between
tion as well as providing internal window cills.
gaps between components than is the case
boards in the platform frame can have
with other materials.The economic nature
timber trims and fillets added that protect
from big timber sections fixed back individu-
of plastic-based cladding is beginning to be
the end grain of the timber from rainwater;
ally to a backing wall, in the manner of an
recognised in new buildings, particularly with
where the timber is particularly vulnerable.
open jointed timber deck set vertically, to
the ability of plastics to be coated in different
Joints between timber cladding panels use
timber panels with louvres and sliding slat-
colours economically, unlike the dominant
a mixture of metal trims and rubber-based
ted panels.The positioning of metal fixings
use of pre-coated coil in metal panels, but
seals in the manner of unitised glazed walls,
is critical to the visual success of all these
the prejudice against the material for its dis-
with a drained and ventilated chamber
timber cladding methods. Corner brackets
coloration in older examples has yet to be
behind the outer timber cladding.
and fixings have a tendency to be large in
overcome in architectural applications.
An important consideration in the
Timber rainscreens vary enormously
order to give a secure fixing, so attention to
detailing of timber is that the thermal
detail of brackets and fixings is essential to
conductivity of both softwoods and hard-
achieving an elegant appearance.Traditional
woods is very low, from 0.14 - 0.21 WI
techniques used lapping of timber boards,
ment than the other materials described,
m2 K, compared to 45 W/m2 K for steel
with concealed nails and screws to protect
mostly as a result of changes in moisture
and 2000 W/m2 K for aluminium. Thermal
fixings from corrosion, but contemporary
level within the material. Consequently,
breaks are not a significant issue in timber
detailing has much less emphasis on lapping
timber used in facade cladding is allowed to
construction, which eases considerably any
in order to give greater visual precision to
accommodate movement as well as being
issues of thermal bridging around openings.
the construction.
ventilated to ensure that bowing, twisting
This allows enormous fiexibility in timber
and warping of timber components is mini-
detailing with a reduced risk of condensation
mised. In detailing timber it is difficult to form
occurring either within the construction or
joints that perform well in tension without
on the inside face of the wall in temper-
the need to introduce another material, usu-
ate climates. Openings in timber walls are
ally metal. Metal pin connections, nail plates,
increasingly using metal trims to enhance
cleats and angles are an integral part of the
the visual refinement of details. Metal trims
Timber Timber is susceptible to more move-
MCH
89
als 02 Generic wall types
This section discusses changes over the past
years have suggested that no clear pattern
stone)
ten years in the 17generic non-loadbearing
of usehas emerged in the use of cladding
- Stonecladding
cladding types set out in this chapter and
systems.The choice of cladding system is
- Terracotta rainscreens
further identifies a smaller set of six generic
very much affected by building type andthe
- Timber cladding to platform frame
types from this list.The application of this
number of a particulartype built in a given
- Timber rainscreens
set of cladding types in 'thin' and'layered'
year.The full range of cladding systems in this
facades is discussed as well as how these
book is in full use.The preference for one
Also from the list, generic types for open
facades are slowly developing from the use
system over another is very much driven by
framed structures are as follows:
of technology from other industries.
the building type and particular performance
- Metal profiled cladding
criteria and budgets of individual projects.
- Metal composite panels
A clear pattern that is emerging isthat the
- Metal mesh screens
choice of cladding systems available has
- Glass sticksystems
I. Fully supported sheet metal
not affected the move towardsthe emer-
- Glass unitised systems
2. Profiled cladding
gence of a new set of generic types, which
- Point fixed glazing (clamped and bolt fixed)
The generic types are as follows:
3. Composite metal panels
are common to all the 17cladding types.
- Glass blocks
4. Metal rainscreens
From these generic types it is clearthat the
- Steel framed glazing
5. Metal mesh screens
different types are support ed by either a
- Precast concrete panels
6. Glass stick systems
monolithic structure, or a backing wall to a
- Polycarbonate insulated systems
7. Glass unitised systems
frame, or alternatively to an open structural
8. Point fixed glazing (clamped and bolt
frame. Each generic type is rarely supported
fixed)
by both structural types. Since framed con-
Generic forms Sixgeneric cladding types are identified
9. Glass blocks
struction is more recent, the more recently
below which are common to both non-
10. Steel framed glazing
developedtechniques of glazing are used
glazed and glazed cladding systems.The first
I I . Precast concrete panels
in conjunction with frames.Traditional load-
three types are used for small span applica-
12. Masonry facings to cavity walls (brick,
bearing structures continueto be used in
tions with a backing wall.The second three
block, stone)
conjunction with traditionally-based tech-
types are used for large span applications
13. Stone cladding
niques. Structurally, the traditionally based
without a backing wall.
14.Terracotta rainscreen
cladding is characterised by techniques that
15. Polycarbonate insulated systems
use materials in short spans.
Three types for small span applications wit h
16.Timber cladding to platform frame
From the list, these short span generic types
a backing wall:
17.Timberrainscreens
for monolithic structures (and backing walls to frames) are as follows:
I. Fully supported sheet with sealed joints 2. Facings wit h sealedjoints:facings to
All these systems still in use have undergone technical development to improve
Fully supported sheet metal
masonry cavity walls, glass blocks, masonry
performance, largely concerned wit h energy
- Metal rainscreens
cladding, timber boarding
conservation. Reports over the pastten
- Masonry facings to cavity walls (brick, block,
3. Rainscreens with open joints:masonry,
MCH
90
with a structural capability, coupled with
with specific tasks of excluding rainwater
controlled light and heat transmission, is a
and controlling heat loss and heat gain,glare,
Three types for large span applications with-
strong infiuence in the design of facades. It
and ventilation.To achieve this, a layered sys-
out a backing wall:
reduces thickness of external walls, allow-
tem superimposes generic types. A current
4. Self-supporting profiled sheet
ing floor areas to be maximised. It allows a
disadvantage of this system is that a layered
5. Stick systems:metal, glass, point fixed glaz-
single,competitively priced product, such as
facade requires considerably more depth of
ing, insulated polycarbonate
body tinted tempered glass, to fulfil a range
'wall', from around one metre where exter-
6. Panel systems: Precast concrete, timber,
of functions. In these 'thin' or 'compressed'
nal solar shading is provided, to about three
metal composite, glass unitised
facades, functions of weatherproofing, ther-
metres, where the zone between the inner
mal insulation, air handling and glare control
and outer wall becomes a usable space in a
are compressed into a very thin wall.
building in the manner of a conservatory or
timber boarding, metal, mesh screens
The application of these generic types in 'thin' and 'layered' facades
Over the past 15 years,this principle has
winter garden.
been developed to incorporate other comModern single-sealed glass framing sys-
ponents within a narrow depth. Louvered
tems used in building construction, which
blinds and mechanical ventilation can now be
rely on silicone bonding and rubber-based
incorporated. Heat from solar radiation can
pressure seals, together with tempered,
be partially absorbed by blinds set within the
body-tinted glasses, are based on techniques
depth of a IOOmm to 300mm deep dou-
developed by glass manufacturers for the
ble glazed unit. Air passes through the unit,
car industry: Car manufacturers are relatively
drawing away heat from the blinds, providing
few in number, but they place very large
a thin external wall whose performance is a
orders for a restricted range of specially
balance between different, and sometimes
designed glass products such as windscreens.
confiicting, criteria. In these thin facades, the
The building industry, in contrast, generates
integrated blind will absorb heat during peri-
relatively small orders from a huge number
ods of high solar gain when blinds must be
of customers all of whom have quite dif-
orientated to act as a radiator of heat.This
ferent requirements. The current custom
can confiict with occupants' requirements for
built nature of building construction does
daylight. Each facade will respond differently
not encourage, in itself, glass manufacturers
to the changing weather conditions, by either
to invest significantly in new systems.As a
manual or electrical means.
result, most recent developments in glazing for buildings have followed in the wake of
An alternative approach for external walls is the separation and layering of the
those developed for use in cars. Perform-
functions of weatherproofing, ventilation,
ance specifications for car glazing systems
thermal insulation, and daylight/glare control.
apply a complex set of criteria to a single
With this 'layered' approach, specific layers
very narrow 'wall' thickness.The use of glass
in the envelope system are created to deal
MCH
91
ails 02 Metal I: sheet metal
Details I. Metal sheet 2.Standing seam joint 3.Timbersubstrate 4.Thermal insulation 5. Fixing battens 6.Waterproof membrane 7. Backing wall 8..Timber/aluminium window 9. Clips at centres 10. Folded metal profile
Westfield Student Village, London, UK. Architect: Fielden
Jewish Museum, Berlin, Germany. Architect: Daniel Libeskind
Clegg Bradley
System design Sheet metal istypically supported directly on a substrate, providing a system formed from thin sheetwhich can
flat roof to a vertical wall, to inverted
ductility allows them to be formed more
soffit conditions.
easily when used in traditional, site based
The two generic methods for sup-
installations.The 'oil canning' effects of
closely follow a complex geometry with
porting sheet metal facades that suit
sheet metals, which are visible imme-
relative ease, making it very suitable as
different conditions are continuous
diately after installation when used in
a covering to a highly modelled facade.
standing seams and tiled shingles. Stand-
facades, tend to diminish visually as the
This material system has developed
ing seams are suited where long, straight
surface weathers to the characteristic
from its traditional use in roofing, where
or continuous joint lines are required
patina of the metal used.The texture
the standing seam technique is well
or where the facade has gentle curves
remains wit h weathering,giving a hand
established, to a facade material that can
which can be picked out by the joint
crafted appearance which suits visually
cover projectingwindows,externally
lines.Tiled shingles are suited to complex
vibrant facades. Some recent buildings
set structure and areas of flat facade
geometries and smaller scale applications
have even slightly exaggerated this effect
with equal ease. In recent years sheet
where a high degree of surface model-
before installation to create a highly
metal has been used to enclose forms
ling is required. Metal sheet can also be
textured surface finish to the metal.
of complex geometry, on either folded
laid onto a timber-based substrate as
Standing seam metal facades have the
or curved facades. Consequently, this
an outer coveringto a complex form.
essential visual characteristic of highly
system also provides an economic outer
Both methods set the thermal insulation
visible joints at relatively close centres of
covering in projects where wall and roof
behindthe substrate, typically creating a
between 450-600mm.This construction
are combined in a single form, or where
vent ilat ed void between substrate and
method, used traditionally as a roofing
the external envelope is highly modelled
insulation, but this is dependent on the
system, is used increasingly in facades as
in a single form where one material is
construction of the backing wall rather
an economic system that is easy to com-
required for the complete envelope.The
than on the sheet metal layer.
bine with other facade elements such as
principles of rainwater exclusion used on
Standing seam roofs have tradition-
roofs can be applied for use on facades,
ally had a slightly uneven appearance
with continuous joint lines, to form a
due to the softer, more ductile metals
complete envelope from a (nominally)
used, mainly lead, zinc and copper, whose
MCH
92
glazing wit hout the need for reveals and visible flashings.
(
3-D view of w all system with window opening and parapet detail
McH
93
ails OL Metal I: sheet metal
3-D view of profiled metal sheel wall construction Falmouth School's Design and Technology Block,Falmouth, UK,Architect: Urban Salon
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Plan I:10, Profiled metal sheed fixed to concrete backing wall
System details method is used on vert ical jo ints in a
vent ilati on on it s internal face to avoid
pro vides a rhythm of standing seams that
var iety of configurations to suit visual
corrosion.Timber substrat es are usually
do not need to be visually coordinated
requirements.The choice of seam is pri-
vent ilat ed on the ir internal face in order
w it h openings and junctions in the facade,
marily visual, ranging from the w ide rolled
to reduce the po ssibility of damage associated w it h trapped moisture.
Continuously supported sheet metal
Flashings can be formed at window and
seam of traditional lead roofing to the
door openings w it ho ut modular co-
thin folded projecting seam of traditional
ordination and do not require to be spe-
zinc and copper ro ofing. Horizontal jo ints
cifically aligned w it h an adjacent standing
are folded to form a flattened seam th at
ings, including parapets, are formed
seam or shingle edge for a reliable joint
allow s rainwater to run off it w it hout
w it h folded metal flashings in the same
to be formed. When joints are at visually
finding its w ay into a joint.
material. Flashings can be set below the
close centres,at around 400mm, the joint
Tiled or 'shingled' standing seam
pattern provides an overall texture for a
metal facades use flattened folded seams
For both standing seam joints and shingled tile s, openin gs and edge flash-
material at junctions w hich reduces their visibility, enhancing the texture of the
facade rather than defining rows of joints .
on all sides of the panel. Since the same
facade material w here required. Flashings
When used in long lengths from roll s,
source material of metal strip is used,
are typically of t wo visual types: those
the material allows horizontal joints to
metal t iles are usually in w idt hs of around
that formed a visible strip th at laps over
be avoided in smaller scale applications,
450-600mm depend ing on the metal
the face of the adjacent area of metal
up to around 12 metres in length, but
used.The jointing system also performs
sheet, and those that form a shadow gap
cur ved or highly modelled facade / roof
w ell w hen the tile s are set diagonally,
between the flashing and the surface of
combinations require shorter distances
wit h 45° being most commonly used in
the adjacent metal. Since sheet metal
between horizontal joints to accom-
practice.
surfaces are formed by folding over edges
modate the cur vature. In such situations,
Both methods use a continuous sup-
of narrow sheets to form a cont inuous metal
tapered joints are often used, sometimes
porting material, t ypically plywood sheet
surface,they do not have a natural link int o
w it h staggers set into them as used at the
for its ability to form complex surfaces
windows and doors set into a typical facade.
centre of traditional circular metal roofs.
w it h ease.Timber boards are also used,
W indows are often sealed against the back-
but mainly in open jointed configuration
ing wall in which they are held rather than
to support zinc sheet, w hich requires
sealing them against the sheet metal wall.
Where crisp, st raight lines are required in the design, the standing seam MCH
94
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3-D view of window head detail wit hin profiled metal sheet system
® Plan I:5.Standing seam profiles
Vert ical section I:I0 through typical wall system
3-D view of window cill detail within profiled metal sheet system
MCH
95
ails 2
Metal 2:profiled cladding
Close-up of metal profile
Roof assembly process
Details I. Cover strip profile d sheet (can also be 2. Horizontally fixed profile vertically fixed)
CD
3.Air gap ur barrier 4. Breather membraneN apo n 5.Thermal insulatio ber/metal frame wit h 6. Backing wall. typicall y tim roof membrane, or plywood facing and waterp concrete block 7. Floor fin ish 8. Drywall/dr y lining 9. Z section steel fixing rails 10. Ground slab I I. Curved eaves profile 12. Concealed gutter I3. Exposed gutter
0)
assembly 3-D viewof wall and roof
MC H
96
Vacheron Con stantin Headquarters. Geneva.Architect: Bernard Tschumi
II
(0
II 3-D view of concealed gutter
System design in the 1970sto wider architectural applica-
cover strip or recessed shadow gap joint is
metal cladding and the continuously support-
tions.This material system uses a single metal,
needed,which createsa break in the system.
ed type isthat profiled sheet can span 3-5
either steel or aluminium, for the complete
Since the shape of the profile cannot be varied
metres between supports,depending on the
cladding of,typically. manufacturing or storage
in regularmanufacture,the lines of the sheet,
(sectional) profile used.The profile depth pro-
buildings which have large shallow pitched
and visible joints at geometric changes in the
vides rigidity of the material in one direction,
roofs and a relatively small facade area in rela-
system,dominate its appearance. In common
allowing it to be fixed directly to a structural
tion to that of the roof.The all-metal envelope
with standing seam metal, profiled metal sheet
frame ratherthan requiringthe continuous
evolved,in an architectural sense, with the
does not have windows and doorsthat fonm
support of an additional substrate.Its profile
introduction of curved eaves and concealed
part of the material system,though these
allows the sheet to be gently curved in one
gutter with walls and roof appearing to be a
items can be made in the same mat erial and
direction during installation on site,with the
continuousform.The profiled metal sheet was
finish. Because windows and doors are made
material still lapped on all edges regardless of
set with the ribs running from top to bottom
by differentmanufacturers, it is important to
its orientation. Profiled sheet can be curved
of the roof and continued down the facades
ensure either colour matching at the fabrica-
along its rigid length by crimping in the factory.
in the same alignment.As its use in facades
tion stage,or contrasting colours/finishes
usually to fonm curved comer pieces for hor-
developed, profiled metal cladding was used
that work together visuallyW here the inner
izontally-set cladding,or curved eaves pieces
horizontally rather than vert ically. in order to
lining of the wall isalso fonmed in profiled
for vertically-set cladding. Proprietary systems
curve the wall profile when seen in section,
metal sheet (typically flatter,and sometimes
offer a range of curved components as well
and at different angles, in order to intro duce
perforated for acoustic perfonmance) a similar
as 90° comers where short lengths of sheet
an expression of complex geometry
approach istaken.
The main difference between profiled
arewelded to fonm a crisp corner panel.The
As a material system,the profiled nature
System details
wide range of profiles available,from small
of the material requirescontinuity of the pro-
wave profiles to deep profiled sectionsgives a
file from sheet to sheet, making it difficult to
wide range of visual effects.
create visual offsets in the setting out of the
metal flashings at the top and bottom of
material.Where a change of orientation or
the wall to fonm parapets and cills, as well as
direction is needed by the design,a projecting
comers, usually madefrom flat sheet. Some
Profiled metal cladding has developed from its initial application in industrial buildings
Vertically-set sheeting requires folded
MCH
97
Walls 02 Metal 2: profiled cladding
@
\ \
3-D view of wall and roof assembly.
manufacturers provide crimped fiashings for
beneath. A metal fiashing is used to close the
corners in order to provide visual continuity
gap between the roof deckand the parapet
between adjacent facades.Where fiat sheet
upstand where the roof isalso clad in pro-
is used at corners, plastic or foam-based filler
filed metal sheet. Where only a low upstand
pieces form part of the system to close the
is required, as at the gable,a folded flashing
gaps betweenthe profiled sheet andthe fiat
is fixed to the roof surface to form a sealed
metal fiashings that are usually set onto the
edge.A metal coping fiashing isthen fixed
face of the profiled sheet.The visual impactof
to the upstand and is folded down the face
these filler pieces needs to be assessed within
of the external wall. Althoughthe thermal
the design. Horizontally-set sheeting can be
insulation formingpart of the wall construc-
formed as continuous cladding with barely
tion is madecontinuous with that of the roof,
visible joints resulting from lapping the sheets.
the void in the parapet is usually filled with
Alternatively. the profiled sheet can be divided
thermal insulation to avoid hightemperature
Vertical section I:I0 through profiled cladding wall
into bays, formed with vert ical joint s closed
variationsbetween outside and inside the
construction
with cover strips or with recessed pressed
construction.
I
(top hat) sections. At roof level, parapets are formed with a pressed metal coping with another flashing
MCH
98
The void behind the sheet is filled with thermal insulation which requires a vapour barrier on its internal (warm in winter) face.
+-
, I
I I
I -~
. - .- -------I
I
I
1
Horizontal section I: I0 through wall system
Verti cal section I:I0 through gutter
3-D view of exposed gutter detail
The internal lining of the wall can be in any
sion requires careful installation of the clad-
material, though dry lining or an additional
ding sheets on site in order to achieve the
layer of profiled metal sheet istypical.Some
relatively narrow corner joint widt hs. Cover
manufacturers have proprietary lining sheets
strips usually have their edge folded backto
in metal which are flatter thanthe external
provide a crisp linearound the profile. Folded
profiledsheet to suit the typical requirements
flashings are usually in two parts,with an inner
of internal fini shes.
seal between cladding and window,andan
Openings for windows and doors are sealed with metal flashings that can be determined as much by visual requirements as
addit ional outer flashing which is sealed with silicone backto the profiledmetal. Although proprietary systems are avail-
by the needs of weather proofing.W indow
able it is easy to adapt these systems, where
openings often have wide cover strips around
the facadefabricator makes flashingsto suit
the edges of the opening to provide a full
individual requirements. Principles of details
weather tight seal which forms a highly visible
are well understood by fabricators and com-
Vacheron Constantin Headquarters, Geneva,
part of the design.
plete proprietary systems are not alw ays
Architect: Bernard Tschumi
Corners can be madefrom either exter-
required.
nally set cover strips or by recessed corner flashingsto suit the design.The recessed ver-
MCH
99
Walls 02 Metal 3:composite panels
I I I
\ \1 I
\I
A bove: 3-D view of assembly. Panels spanning vertically and ho rizontally Right: De t ail of metal bracket and capp ing suppo rting panels
System design This material system provides a com-
part of their fabrication,wit h panels being set
which usually contrast visually with the ver-
plete wall assembly in a single panel form,
either vert ically or horizontally. Joints are typi-
tical joints which have wider sightlines in
sometimes with integral windows and doors
cally formed to avoid a thermal bridge from
order to accommodate a metal cover strip,
that interlock with the regularpanels. Panels
insideto outside, by creating a small break
a rubber-based gasket, or their combina-
consist of an inner core of rigid thermal
between inside and outside layers of metal,
tion. Since vert ically set panels are typically
insulation onto which a thin metal sheet is
and are shaped to ensurethat rainwater runs
separated by the flashings, vertical joints can
bonded to each side,wit h a specially formed
back out of the panel. Joints between panels
be discontinuous, allowing windows to be set
profile around the edges of the panel that
at their short ends, where there is no inter-
in specific locations on a floor-by-floor basis,
forms a weathertight connection with adja-
locking joint, are butt jointed and sealed with
with each floor having its own arrangement
cent panels.This material system is made
cover strips. Panel systems are also used with
of composite panels that is not aligned with
as complete proprietary systems, each wit h
interlocking joints on all four sides, and these
those on the floor below.This has given rise
varying levels of interchangability and surface
are usually made in sizes that can easily inte-
to the use of mixed panels, set both vertically
finish in relation to their cost.Their main vis-
grate doors and windows which also form
and horizontally, in a tiled arrangement rather
ual advantage isthe smoothness of the panel
part of proprietary systems.
than the exclusive use of the rectilinear grid
faces that form a complete system with inte-
Vertically-set panels that interlock on
gral panels for corners, parapets and window
tw o sides are usually sto rey height. W here
openings.Their maintechnical advantage is in
panels are stacked over more than one
seen until recently. In four-sided interlocking panels, joints usually incorporate an inner chamber set
providing a complete wall construction in a
storey, the horizontal joints between panels
between an inner and outer seal in order
thin panel which is also highly thermally insu-
are usually sealed with metal flashings. Panels
that the system be internally drained and
lated. Panels are typically made in widths of
are support ed on horizontal rails,typically
pressure equalised.W indow and door frames
I IOOmm to 1400mm to suit the manufac-
at floor level to allow a floor to ceiling panel
interlock into the surrounding panels and are
tured width of metal coil,but are long, up to
arrangement without intermediary structure
of a depth equal to that of the composite
around 15 metres, where transportation of
that would be visible from inside the build-
panels. Interlocking joints are usually made
the panels becomes a primary consideration
ing.Hor izontally-set panels that interlock on
sufficient ly rigid to allow two or three panels
oftheir size. Panels typically have interlock-
tw o sides are stacked one above the other;
to be used in a storey heightwithout vis-
ingjoints on two sides, forming an integral
wit h tongue and groove horizontal joints.
ible support ing structure. For both vertical
MCH
100
Composte panel with vertaical capping and interlocking horizontal joints
Connection profile for vert ical two-way interlocking profiled panels
Usera Public library, Madrid.Architect: Abalos & Herreros
Details I. Composite panel 2. Panel fixingto primary or secondary structural steelwork
3. Polysulphide or silicone-based seal 4. Outer metal facing 5. Inner metal facing 6. Inner insulation core 7. Metal capping 8. Interlocking fixing 9.W indow frame I O. Roof parapet I I. Gutter 12. Special panel highlighting floor level I 3. Floor slab 14. Roof 15. Steel column I 6. Curved corner panel 17. Special corner panel
Ferrari dealership, Zauemten, Belgium.Architect:Van der Str icht
Interlocking composite panel profile
MCH
101
W alls 02 Metal 3: composite panels
l Office building, Lippstadt,Germany
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3-D view of vertical section showingtypical wall details
MCH
102
Section I:I0,Wall build up showing typical details
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Plan I: I0 Corner details and special application panels
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10 @ Section I: 10. Corner details and special application panels
3-D of special corner panels
and horizontal orientation of panels,this
doors are recessed. In recessed window and
barrier on the internal (warm in wint er) face
material system requires a supporting metal
door openings, flat metal panels are used
of the insulation in order to provide conti-
frame,typically in mild steel, but sometimes
to closethe gap between the face of the
nuity of insulation between wall and roof.
in aluminium.This frame is arranged in a way
composite panels and the window or door
Colour matching between metal flashing and
that will support the edges of the compos-
frame. Some manufacturers of composite
composite panel is essential to the success
ite panels, and is fixed backto the primary
panels offer special corner panels for win-
of this method, unless a completely different
structure of the building.The visual charac-
dow reveals which are also used at internal
colour is used for folded metal items. Four-
teristics of the supporting frame are usu-
and external corners of the facade, and
edge interlocking systems allow the possibility
ally secondary as they are often concealed
others have a range of preformed panels
of a thin parapet coping of around IOOmm
behind the interior finishes of the building.
for cills, corners and parapet copings as
that forms a visual continuity wit h the panels
W here visible,they form an essential part of
part of their systems.This avoids the need
beneath.Any water that penetrates the outer
the material system, and are often formed
for visible metal flashings which lap down
seal is drained awayto the base of the wall
from rectangular hollow sections.
over the face of adjacent composite panels
within the drained and ventilated framing
to provide a lapped joint,and have a flatter.
to the panels.W indows are often given the
smoot her appearance when compared t o
same colour and finish in order to provide a
pressed metal flashing panels. A wider range
visual continuity between window frame and
locking panels have windows and doors as
of interface components are usually available
composite panel, giving the facadethe visual
separate components which are coordi-
on four-edge interlocking panels to add to
crispness previously associated with fully
nated with the material system to varying
the seamless clipped-together appearance of
glazed walls.
degrees, with four-sided interlocking systems
these systems. Parapets are typically formed
being the more closely integrated.W indows
with a pressed metal flashing that folds
and doors are fitted in a way that they are
down the face of the facade but can also be
either flush wit h the external face of the
created with a parapet panel which can be
composite panels in order that the same
flat or curved to suit the design. W here a
panel to panel flashings can be used t o seal
pressed metal flashing is used, a layer of ther-
the door/window, or alternat ively windows/
mal insulation is set beneath, wit h a vapour
System details Both two-sided and four-sided inter-
MCH
103
W a 502 Metal 4: rainscreens
Bridgewatchers House, Rotterdam, Holland, Architect: Bolles and Wilson
3-D of rainscreen wall construction
System design This material system uses the rain-
monolithic appearance as the joints are
scale applications, since rails are much faster
screen principle of allowing rainwater to
less visible. Rainscreen panels can provide
to fix than individual brackets,
pass through open joints,or partially open
a flatness or consistency of texture across
Sizes of rainscreen panels are determined
joints,where the water is drained away
a facade that is independent of the back-
by available metal sheetsizes, Metal coil is
backto the outside of the building. Panels
ing wall behind. Most panels are fixed so as
supplied typically in 1200mm and ISOOmm
are set typically forward of a waterproofed
to avoid visible fixings. Face fixings on the
widths,with metal plate in greater widths
and thermally insulated backing wall. Wind
metal sheetare usually not preferred since,
and in varyinglengths, Metal-faced composite
driven rain that passes through the outer
at around 3mm thick,point fixings on a thin
materials are also used, comprising either a
open joints is drained away down the cavity
sheetcan produce visible distortions across
thin metal sheet, such as aluminium, bonded
between the backof the rainscreen panel
the panel surface, Panels are usually formed
to both sides of a rigid plastic core or,alter-
and the outer face of the backing wall, The
as trays or 'cassettes' with folded edges
natively; a single sheetof metal bonded to
backing wall is typically of economic type as
that provide rigidity to the panel a well
one side of a honeycomb panel. Composite
it is not visible if interior finishes are applied
asa depth to the joint that both reduces
materials that usea thin (3-Smm thick) inner
within the building, Metal rainscreen panels
rainwater penetration and obscures views
plastic-based core can be folded to form
are given typically either a completely open
into the void behind. Most panels are fixed
trays, but honeycomb panels require either
joint with framing behind positionedto close
with either a hook-on fixing or with slotted
an edge strip to conceal the joints,or are
views into the void behind, or have folded
grooves in the manner of composite metal
set close enough together for the inner core
edges on the panel to close the joint visually;
panels that avoid the need for anyvisible
not to be visible,An alternative method of
but not to seal it. Small amounts of rainwater
fixings, With hook-on supports, panels have
fixing panels is to form a folded tongue and
that pass through the outer joint are drained
brackets that are fixed to the sides of the
groove joint on the long edges of the panel
away in the ventilated void behind,Visually,
panels that form the tray. Panels are fixed
where panels slot together. An advantage
this material system provides visually crisp
onto vertical rails which are usually aligned
of this method isthat the support framing
joints with strong shadow lines to the metal
with the joints where they serve as a screen
behind can be simplified with vertically-set or
panels,The useof narrow joints between
to the void behind. Continuous rails are pre-
horizontally-set rails to suitthe pressed metal
panels can give the metal panels a more
ferred to individual fixings except in small-
panels where concealed fixings can be used,
MCH
104
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3-D view of window and parapet detail in rainscreen wall systrem
Verti cal section I:I0 through parapet showing typical details
Details I. Backing wall or structural wall
I I. W indow cill
supporting rainscreen
12. Pressed metal coping
2. Support frame
13. Continuity of waterproofing layers
3. Support bracket
of wall and roof
4. Metal rainscreen panel S. Open joint 6.Closed cell thermal insulation 7.Waterproof membrane 8. Finish to inner wall 9. Roof finish 10.Wi ndow frame inserted into opening in backing wall or structural wall
MCH
105
W alls 02 Metal 4: rainscreen s
3-D of basic rainscreen panel system
System details
panels are formed typically either from fold-
An essential aspect in the design of
ed sheet or thin composite sheet, or alter-
metal rainscreen systems is the layout and
natively w it h mitred panels that meet at the
fixing of the framing th at suppo rt s the rain-
corner, particul arly w here honeycomb panels
screen cladding.A lt ho ugh panels can be
are used. Internal corners are formed in the
set out independentl y of the backing w all
same w ay, but their geomet ry allow s panels
behind , w hich is o ne of their primary advan-
t o meet w it hout any special panels w it h
tages,the need to fix panels economicall y
two panels buttin g up to one anothe r.The
makes it essential to engage wit h the idea of
co rner condit ion is an important junction,
their fixing during the detailed design st age.
from a visual point of view, as the th in nature
This is of particular importance w here rain-
of rainscreen panels can be either exposed
screen panels are set out to coordinate visu-
o r concealed at thi s point. Butting panels
ally w it h w indow openings.The o pen jointed
together w it h an o pen joint o n th e corner
nature of the rainscreen panels allow s the
can make it difficult t o create a visually sharp
Lock-keeper's Graduate Centre, Queen Mary, Uni-
junction w it h w indows to be straightforward
edge to the facade, w ith any imperfections in
versity of London, UK.Architect: Surface Architects
and visually dri ven, as w indows and doors
the setti ng o ut of panels being apparent.
MCH
106
are sealed t o the backing wa ll, w it h w hich
Parapets are form ed in a similar way
the y form a continuity At facade corners,
t o corners, w it h panels fabricated to suit
CD
Horizontal section I:I0 showingtypical details
Vertical sect ion I: I0 showing typical details
3-D view of wall construction illustrating panel fixingarrangement
particular project conditions as a part of
nated adjacent t o the window in order to
manufactured systems. Since the coping is
conceal the seal between window and back-
sealed between panels on its horizont al face
ing wall. In order to avoid staining from dust
to avoid rainwater fallingdirectly through
and dirt, cills are usual ly formed in a way that
the joint between panels,t he joint is often
directs rainwat er to the sides of t he opening
recessed to match with the open joint on
and down joint s between panels rather than
its external verti cal face.The coping usually
directly down the face of the panels below.
has a little gap between the coping panel
Drips at ground level are formed as pressed
and the inner face of the parapet upstand in
metal fiashings, with the gap between t he
order to ventilate the cavity, where the joint s
panels and the backing wall being closed
between the facade panels do not admit suf-
with metal mesh that allows the passage of
ficient air for vent ilat ion.
air for ventilation but avoids t he ingress of
Because windows in openings are sealed directly against the waterproof layerof the
insects into the ventilated void.Although manufacturers offer metal rainscreen panel
backing wall the visual treatment of the junc-
systems,they can be modified designed to
tio n of panel and window requires attent ion
suit individual projects and fabricated eco-
during design to avoid an uncoordinated
nomically
alignment.The rainscreen panels are termi-
Lock-keeper's Graduate Centre, Q ueen Mary, University of London. UK.Architect:Surface Architects
M CH
10 7
Metal fixings for mesh flexible in one direction
Elevat ion and vertical section I:25 showing typical screen arrangement
Below: Maison Folie, France.Architect: NOX
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2. Stainless steel mesh
8. Insulat ion
3. Stainless steel spring
9.Wi ndow Frame
4. Metal fixing bracket
I O. Floor slab
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5. Fixing bolt
I I. Pressed metal parapet
6. Framed perforated metal sheet
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SunTower Office Building, Seoul. Architect: Morphosis Architecture
MC H
108
Example of mesh weave pat-
1:2 Section thro ugh woven
terns
mesh fixed to wall
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Vertical section 1:2
System design has led to a greater interest in using more
made from either greater diameter rod or
as a material system from the early I 990s
rigid meshes made from rod woven in both
smaller panel sizes.
with the introduction of woven stainless
directions, where the material is set into a
steel and woven copper to provide light-
frame at its edges. Consequently, there are
is sometimes woven in groups of cable,
weight screens,typically as screens. From
three generic types of varying rigidity: rigid
running the length of the material, with
its origins in industrial applications, such as
mesh, mesh flexible in one direction and fully
thin rods woven into these cables in the
woven metal conveyor belts, stainless steel
flexible mesh.
opposite direction, across the width of the
Metal mesh in facades has developed
mesh is used in facades for a variety of func-
Rigid mesh is made from rods which
Mesh which is flexible in one direction
material, creating a visually textured surface.
tions: solar shading to glass walls, guarding to
are woven in two directions that can use
The material is manufactured in long lengths,
full height balustrades, and as visual screen
very similar patterns to those where cable
allowing it to be used as a continuous facade
to backing walls.Woven stainless steel has
is used in on direction. The material is made
'wrapping' material, either tensioned hori-
cables set in one direction, which can be
in relatively small panels of around 1800mm
zontally across the facade or hung from top
tensioned at points or along its edges to
x 1500mm, and is fixed by clamping the
to bottom. Meshes are typically hung to
provide a rigid, lightweight screen that has
materials into a continuous edge frame or by
reduce the sagging that could occur when
little visible supporting structure, while metal
point fixing, since the material cannot be ten-
used horizontally, but cables beginning to be
rods set perpendicular to the direction of
sioned.The diameter of the rod is typically
set at different angles, even 45 from the
the cables provide rigidity in one direction.
around 2mm set into a grid of 6mm x 2mm.
vertical direction.These meshes are usually
Stainless steel is preferred to mild steel
They are joined to form a continuous wall of
made in widths up to around 7500mm but
for its greater durability and resistance to
mesh panels where the grid of the frame can
they require restraint at close centres if used
corrosion. Copper and bronze are being
dominate visually. Because no cable is used
as guarding, as their deflections can be high.
introduced, but the lower tensile strength
the material can be colour coated or etched
A wide variety of weave pattern is used to
of these materials currently limits their use
to create specific visual effects.Where alu-
suit different amounts of transparency, rigid-
to smaller scale applications. Becausethe
minium is used (which is not as rigid as stain-
ity and weave. Light transmissions ranging
cables require tensioning, their supporting
less steel), the material can be anodised in
from 25% to 65%, making them very suitable
structure can be visually prominent, which
addition to these finishes, though panels are
for solar shading where a specific percent-
0
MCH
109
W alls 02 Metal 5: mesh screens
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Panel junction of perforated metal screen
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External corner of perforated metal screen
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Vertical section and elevation I :25, Mesh flexible in onedirection fixedto brackets supported on adjacent wall age of shading is required, Light transmission
available,which resemble thin cable woven
can be reduced by reducingthe distance
in two directions.These are manufactured in
between cables, between rods, or a com-
widt hs of around 6000mm, requiring restraint
bination of both, dependingon the visual
at around 1500mm centres.The material is
effect required, Cablethicknesses vary from
held in place by tensioning the material in
2mm to 6mm wit h rod diameters ranging
two directions,typically in an edge frame, but
from around 2mm to -lrnm,W eave patterns
where panels can be as wide as the material
can be as dense as 4mm x IOmm for low
as manufactured, subject to its defiections
light transmissionto 4mm x IOmm for high
beingwit hin the limits of its prescribed use.
light t ransmission, Meshes can also incorporate a varying weave wit hin a single length of material t o suit varying light transmission requirements. Fully fiexible mesh is less commonly used
Museum of contemporary art, New York, USA Architect: 5AANA
MCH
110
o
System details W here rigid mesh is fixed into a frame around its edge, the material is usually clamped between fiat bars, or angles of the
in facades, but has a visually rich appearance
same material.The plates are clamped wit h
as a result of its non rectilinear open weave.
bolts,which can be countersunk to avoid
Metal widt hs range from around 1800mm
highly visible fixing bolts.The frames are then
to 2400mm and are manufactured in long
fixed back to the facade on support brack-
lengths. More open weave versions are
ets. A n alternat ive edge frame is to use a
Kew House, Melbourne,Australia.Architect: Sean
Carter Tucker house,Victoria,Australia.Architect:
Godsell
Sean Godsell
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3-D view of mesh panel in front of curtain wall glazing
C-shaped folded section int o which the rigid
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Section I:10 Parapet of perforated metal screen
support methods can be used at the ends
mesh is fixed. Rigid mesh can be curved in
of the cable. Cables can be turned over a
either one direction or two directions to give
continuous rod at its ends to form a loop,
a highly modelled surface.The form of the
wit h the rod being suppor ted on individual
curves is typically influenced by its support -
brackets to suit the design rather than being
ing structure, which needs to be a balanced
aligned wit h each cable. Alternat ively, the
blend of structure and mesh to avoid the
continuous rod can be woven into the mesh,
support ing structure from becoming visually
usually during manufacture, wit h the rod
dominant.
being supported in the same way.
Mesh which is flexible in one direction avoids the need for a highly visible supporting frame,but typically requires substant ial mild steel brackets projecting from the facade that can absorb the tension in the cables at each end. Panels can be set side by side to creat e a continuous texture of material across
Peninsula House,Victoria,Australia.Architect: Sean Godsell
a facade, which is one of its preferred visual characteristics.W het her the material is set vertically or horizontally, a similar variety of
MCH
III
Wal ls 02 Metal 6: louvre screens
3-D view of metal louvre screen
System design Metal louvres are used typically in
angle, but allows views through a small part
need for changing the system to accom-
facades either to provide weather resist-
of the facade when directly facing the facade.
modate the louvres, simplifying the interfaces
ance to the ends of ducts for mechanical
Deeper vertically-set blades increase the
between glass/metal units and the open lou-
equipments or as acoustic screens. Glass
screening effect for views at close prox-
vre panels. W ater that penetrates the glazing
blade louvres with metal frames are used
imity to the louvres. Where more than a
system is drained awaythrough the drained
to provide ventilation to daylit spaces such
single row of inclined blades is needed in
and ventilated cavity of the curt ain walling
as semi-open circulation spaces where high
horizontally-set louvres, typically to improve
system. Metal louvre blades are usually made
levels of thermal insulation are not required.
their weather resistance, rainwater is drained
from extruded aluminium or mild steel.Alu-
The orientation of metal louvres is as much
by forming a groove along the bottom edge
minium istypically polyester powder coated,
a visual consideration as one of t echnical
of each blade to drain away water thro ugh
while mild steel is galvanisedand painted.The
performance,with the blades used to con-
the sides of the louvre frame,then down the
useof aluminium providesprecisely formed
ceal views through as well as to allow the
base of the frame and backto the outside.
sectionsthat can both encourage the passage
free passage of air thro ugh the panel.For this
The perimeter of the frame is sealed against
of air through the panel and minimise rain-
reason metal louvre blades can be set either
the surrounding waterproofed wall where a
water penetration.The blades are fixed into
verticallyor horizontally with an orientation
different material is used for the surrounding
a perimeter frame also formed from extru-
that avoids viewsthrough the blades.At
area of facade.
sions or angle sections to suit the frame size
ground/street level, horizont al blades usually
W here metal louvres are set into a
and method of drainage. Mild steel is often
conceal viewsthrough the void behind, but
curtain walling system,blades are placed
used where greater resistance to accidental
above ground floor level,the 45° orientation
in a perimeter frameto form a complete
damage is needed, asthe material better
of the blades allows views through unless
panel which is then fixed into curtain walling
withstandsthe effects of local impacts than
an additional bank of blades is added,which
framing in the same manner as a glazed unit
aluminium,and can also be accommodated
both improvesweather protection and
or metal panel would be fixed.This is par-
within curtain walling systems.
conceals viewsthrough the panel.Vert ically
ticularly useful where a glazed wall has a few
set blades provide a screen that conceals
louvre panelsthat form part of the facade.
views through when seen at an oblique
The louvres can be introduced wit hout the
MCH
112
Details I . Ext ruded aluminium frame 2.Curtain w all carr ier system 3.Extrude d aluminium louvre blades 4. Floor Slab
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Louvre panel fixing det ails
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3-D view of louvre panel fixing to cur t ain wall system
Ver t ical section I :25. Met al louvre systme and fixing elements
MCH
11 3
f1e al a Metal 6: louvre screens
Above and below: Nordic embassy, Berlin, Germany. Architect: Berger & Parkkinen
3-D views showing profiled aluminium louvres and fixing system
MCH
114
3-D view of lo uvre panel set in fro nt of glazed curtain wall facade
System details Metal louvre panels are made in widths
which shading is provided. Since aluminium
minium that provide structural support to
of 1500mm to around 3000mm to suit the
is extruded economically in widths up to
the blades. Clips are linked to rods that form
facades into which they are set. Individual
around 300mm, depending on the profile
part of the supporting frameto the louvres.
blades are support ed by vertical or hori-
design, metal louvres used for solar shading
The rods move up and down, allowing the
zontal framing members alongthe length of
are often made in combinations of curved
louvre blades to be moved to opened and
the blades in order to provide the required
sheet and extrusions linked together to form
closed positions to suit both ventilation and
stiffness in addition to the perimeter frame
a complete shape.The resulting forms of
solarshading requirements. Movement of
required for each panel. Because of the
these blades are also finding an application
the blades is controlled either manually with
required technical performance and visual
as regular louvre blades in facades where
a winding mechanism, or electrically, with
criteria required of louvres, they are made
the increase in scale makes them a more
louvres operated in groups of panels. Panel
as proprietary systems which are adapted
integrated part of the language of metal
sizes are around a maximum of 1500mm
to the requirements of individual projects.
panel facade design. Larger scale louvre
high x 1200mm wide. Glass blade louvres
Doors in louvre panels are usually formed in
panels allow them to be used as both fixed
provide around 70% free area when fully
a similar wayto fixed panels to avoid them
or adjustabletypes on a single facade, where
open.Thermal insulation and lower rates of
beinghighly visible, but usually have larger
the louvres are a less visually obvious part of
air infiltration can be achieved with double
frames to provide the required door panel
the design. Mechanisms for moving louvres
glazed units.The maximum length of panel is
stiffness.
typically comprise pivots set on top and
also 1200mm, wit h blade widt hs of around
Metal louvres are also used for solar
bottom with a sliding arm at the bottom to
150mm to 200mm.The high air infiltration
shading as part of double skin facades,typi-
which the blades are connected to provide
rates associated with glass blade louvres have
cally set 750mm to 1000mm in front of a
louvre movement.These can be hand or
been improved in many years, but do not
glazed outer wall.This application of metal
electrically operated.Aerofoil-type sections
significantly affecttheir performance for semi
louvres has led to them being required
can span up to around 3000mm.
external applications, with which they are
in much largersizes set vertically or horizontally to suit the incident sun angles for
Glass louvre blades are held by metal
usually associated.
clips, usually made in cast or extruded alu-
MCH
115
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Exploded view showing assembly of stick based curtain wall
An essential difference between glazed walls
slabs.These are usually made in stainless
are fixed first,then transoms (horizontals)
and those built in other materials is that the
steel,though mild steel and aluminium can
t hen glazing and capping.The glass is fixed
seals in glass construction form a continu-
be used depending the specific application.
with temporary short clamps fist, until it is
ity that usually requires the installation t o
Brackets are fixed eit her onto the fioor itself,
all properly aligned,then the full pressure
be continuous starting at one point in the
or onto the vertical face of the slab at its
plates are applied wit h their rubber-based
wall and sett ing glazed panels next t o each
edge. Fixing brackets directly onto the fioor
seals.This makes stickglazing slower t o install
other t o continue the assembly.This is dif-
slab suits sit uations in taller buildings,where
than unitised types, but has the advantage of
ferent from other mat erial systems, which
access t o the edge would require scaffolding
fiexibility of installatio n on site. Some glazed
often allow for much more fiexibilit y in their
or moving platforms called 'mast climbers'
walls, such as those used for full height
methods of construction,and which do not
which can be slow t o use and suit straight
glazed walls, may be fixed back t o full height
have any significant influence on the design
facades in simple arrangements. Floor
steel frame rather than fioor slabs. If the
mounted brackets are sometimes set into
steel frame is designed as a single structure
The main types of glazing system that
a pocket in the fioor slab in order that they
that does not have the structural move-
use primarily double glazed unite are stick
can be covered by screed and fioor finishes.
ments associated with slab edge defiections,
glazing, unitised panels, point fixed glazing
Office buildings typically have raised fioors,
this provides the opportu nity to omit the
and window walls. In addit ion,the principles
so the brackets can be fixed directly on the
aluminium structural box section on the
of the building.
of these systems can be made as small-scale
fioor slab. If brackets are set on the side of
back of the glazed wall assembly, and fix the
windows set into openings of walls made
the slab then this done usually to avoid con-
glazing assembly directly t o the support ing
in a different material. Glass blocks can also
fiicting requirements at fioor level, such as a
steelwork.
be considered to be a glazed wall, but fol-
thin fioor build-up, or where brackets cannot
W ith unitised glazing, panels are typi-
lows none of these principles, using a stack
be accommodated in pockets set into the
cally hung from brackets and are fixed side
bonded version of masonr y construction.All
slab. It can also be easier to fix brackets on
by side on a single floor;until the fioor is
thesetypes are set out in th is chapter.
the edge of the slab if scaffolding is used.
complete, or as much of it as can be closed
For all glazed wall types the first opera-
O nce brackets are in place, framing
off. Sometimes gaps are left in glazed wall
tion on sit e is usually to fix the brackets that
members or panels are fixed to them. In
installations on site in order t o allow access
will carry the facade system t o the fioor
the case of stickglazing,mullions (verticals)
directly from out side for building materials
MCH
116
Stick system
Panel system
Point fixed system
Glass assembly systems
Stick glazing between slabs
Exploded viewshowing arrangement of opaque infil panel within stick based curtain wall
Stick glazing between slabs with recessed window
Exploded viewshowing window assembly within stick based curtain wall
Stick glazing in front of slab
MCH
117
Walls 02 Glass systems Exploded view of unitised, double skin system with opening windows
Detail of unitised connection for double skin mullion
Unitised, double skin glazed panel
......
3-D view of glazed vertical louvre set into untised glazing system
MCH
11 8
Unitised, double skin panel with opaque infil
Exp loded view of unit ised glazing panel w it h framing for addit ional o paque inser t s
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I
I 3-D section show ing unit ised panel hung Frame detail fo r unitised system
Frame detail for unit ised syst em w it h op aque glazing
used for work inside the building, depending
Larger scale bolt fixed glazingis installed with
account during the stages of design develop-
on climate and site location.Unitised instal-
glass panels being craned into place with
ment.
fro m fioor slab
lations typically start at the bottom of the
bolts or clamps often already fixed to the
building and work upwards, slott ing panels
glass, making it easierto install.These larger
independent sets of windows and fixed
W indow wallsare installed either as
in one above the other, lifted in place by
installations are typically support ed from a
panels fixed together to form a single frame,
crane.This makes it a fast method of closing
steel frame which is built either by install-
or are fixed back to a structural backing
the external wall, allowing work to progress
ing large prefabricat ed sections, sometimes
wall.W here installed as large-scale window
inside the building at earlier stage than
pre-finished, or by using steel sections which
assemblies,the glazing can be installed as
would be possible with a comparable stick
are first set in place and levelled, then have
complete window panels, sometimes of
glazed installation.
prefabricated support s for the glazing fixed
considerable size.This makes the system
in place, which may also be pre-painted.
surprisingly quickto install,tho ugh the weight
Point fixed glazing is fixed in a variety of ways, depending on size of installation and
Clamped glazing is used typically for glazed
associated with large panels require the use
the method of support. Small scale clamped
walls which do not need t o int erface with
of a substantial crane.Wi ndows frtted to a
glazingover one or two floors may be sup-
internal walls,asan edge frame to the glazing
backing wallsoften have the brackets fixed
port ed at its base, wit h clamped used to
is typically needed in such sit uations.
to the wall in advance, either at the sides for
transmit loads down from the to p panel to
Where a glazed roof forms part of the
narrow windows, or on the bottom of the
the floor below.This methods of installa-
same design,the roof elements are some-
window assembly for wider assemblies.The
tion starts by fixing clamps at floor level and
times installed before the glazed wall in
windows are then sealed against adjoining
setti ng t he glass in place from the bottom
order to provide a shelt er to spaces below,
construction in order to provide a weather-
upward,with either scaffolding or tempo-
allowing the work to proceed from the
tight envelope.The infill glass panels are then
rary supports to hold the glass in place. If
top down,away from materials and equip-
installed afterwards,allowing work to pro-
glass mullions are used rather than a steel
ment being moved in and out of the build-
ceed inside the building while this installation
frame,then the glass mullions are installed
ing below.The sequence of installation can
work is conducted in parallel.
along with the glass panels. If a steel frame is
influence the detailed design of glazed walls
used then this is installed before the glazing.
and enclosures, so this should be taken into
MCH
119
W alls 02 Glass systems I: stick syste ms
- - - - -....
__ _ J Basic capped unit ised glazing detail
Uncapped unitised glazing detail
System design This material system is essentially a sitebased method of forming glazed walls, with
cally immediately above movementjoints, Stick glazing systems comprise extruded
be formed in a variety of structural-based sections,that can vary from a rectangular box
mullions (vertical framing members) and
aluminium sections onto which glazed
section to an I-section to aT-section with a
transoms (horizontal framing members) pre-
panels are set. held in place wit h extruded
blade-like appearance.
pared in the factory wit h the slots and holes
aluminium pressure plates which secure the
In terms of panels set into the fram-
required for assembly and installation on site,
panel to the carrier frame wit h screw type
ing, double glazed units are the most typical
Sticksystems are suitable for glazed walls
fixings.A synthetic rubber-based outer seal
panel used, though insulated opaque panels
with either a wide variety of conditions or
is set between the glass andthe pressure
are used for spandrel conditions at floor
complex geometry which makes the use of
plate.A gasket in the same material is also
level, typically faced in metal or opaqueglass.
prefabricated glazed panels uneconomic.This
set between the inner face of the panel and
Spandrel panels are made either as single
method also has the advantage of permitting
the carrier frame to provide an inner air
sealed panels or as panels wit h a separate
a discontinuity of mullion and transom to
seal.The pressure plate is secured with vis-
decorative front panel.Single panels have the
give an ungridded appearance, while main-
ible fixings at around 300mm centres, which
insulation bonded to the inner face of the
tainingthe internally drained and vent ilat ed
are usually concealed wit h a continuous
glass,with a vapour barrier set on the inside
principles of the system, an essential aspect
cover capping in extruded aluminium clips
face of the panel. Alternatively. the spandrel
of this form of glazed wall. This principle
onto the pressure plate.The cover cap is
panel is formed with an air gap between the
accepts that small amounts of wat er will
sometimes omitted where a more utilitar-
outer panel and an insulated panel behind.
penetratethe outer seal of the curtain wall,
ian appearance is required, but the installa-
The insulated panel is typically faced in metal
but this water is drained away in a chamber
tion of the fixing screws needs to be done
on both sides. Where opaqueglass is used as
immediately behind this seal, and returned
wit h additional care, and holesneed to be
the outer panel, care must be takento avoid
to the outside at the base of the wall.The
planned to avoid visually unexpected results.
dust enteringthe air gap from becoming vis-
overall continuity of framing required in stick
The capping profile can be made in a variety
ible on the outer face if the outer panel is
glazing ensures that the internal chamberin
of flat, projectingor recessed profiles to suit
required to be ventilated to avoid a build-up
the transom can drain into an adjacent mul-
visual requirements. Similarly. the supporting
of heat in the cavity.
lion and that any moisture is drained,typi-
aluminium grid of mullions and transoms can
MCH
120
Stickcurtain walling is constructed by
I
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Vertical section 1:5. Opening window within stick glazed wall
3-D view of stickglazed wall with outer glazed screen
CD
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Details
10. Floor slab
I. Extruded aluminium transom
I I. Floor finish
2. Extruded aluminium mullion
12. Ceiling finish
3. Extruded aluminium section
I 3.Thenmal break
4. Single glazed or double glazed unit
14. Projecting bracketto support
5. Pressure plate
external screen
6. Rubber-based seal 7. Metal honeycomb panel 8. Capping piece Vert ical section I :5.Sticksystem with addit ional outer glazed screen to provide solar shading or aspart of a twin facewall
9. Metal-faced or opaque glass-faced insulated panel
MCH
121
Walls 02 Glass I: stick systems
Corner and angled glazing panel connections
spanning mullions vert ically from floor to
by the use of metal flashings or by special
W ith the wiring concealed within the fram-
floor from brackets fixed at each floor level,
components that form part of proprietary
ing,the visual impact of motors and window
by either hanging each mullion and restrain-
systems, such as synt het ic rubber strips that
opening arms has been reduced significant ly
ing it at the floor level below, or by support -
are glazed into the system on one side ofthe
in recent years.Junctions at floors are closed
ingthe mullion at floor level and restraining
strip, and are bonded directly to the face of
by bringing floor finishes up to the transom,
it at the floor slab above.The hanging mul-
adjacent concrete or masonry surfaces on
which is also set at floor level to close off the
lion option usually allows a smaller mullion
their projecting face.This provides a continu-
gap between floors.The spandrel panel has a
to be used, but this depends on the specific
ity of wat erproofing across the interface of
smoke seal between separated floors, but a
application. Mullion sections are joined from
tw o systems, with thermal insulation and
full fire barrier is required in some countries
floor to floor with a sliding connection that
vapour barrier set behind to form a continu-
where the spandrel panel is required to be
allows the glazing between each floor level
ity of the complete construction.
fire resisting and to provide a barrier that
to move independently while maintaining
W indows are fitted into stickglazing by
stops flames from passing from floor to floor.
the overall continuity of the system.The
applying an additional sub frame within the
Corners are formed,typically, either with a
movement joint is visible in the facade and is
main framing against which the opening light
special extr usionthat allows a glass-to-glass
accommodated either at the junction of the
is closed.The overall widt h of the window
junction at the corner, or has two mullions
mullion and the transom above, or within
frame is usually of similar width to that of the
meeting at a corner and an insulated metal
the length of the transom, usually within
main framing of mullions andtransoms. Both
flashing turning the corner. Parapet copings
the spandrel panel. Brackets supporting the
outward or inward opening windows and
are formed by glazing the bottom edge of
framing are fixed either onto the floor at the
door s are used, with some with their frames
the metal flashing into the top transom and
edge ofthe slab,or on the vertical edge of
silicone bonded t o the glass to reducetheir
foldingthe flashing over the top of the para-
the slab.
visual impact externally,though the frames
pet.Junctions between mullions and adjacent
look similar from wit hin t he building. Electri-
areas of wall in a different material are made
cally operated windows, such as those at
in the same way.
System details Interfaces with openings, edges and different adjacent materials are formed either
MCH
122
high level, usually have a motor in a box that fits within the height of the window frame.
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University Library Delft, Holland,Architect:Mecanoo Architekten
ING headquarters. Budapest Hungary.Architect Erick van Egeraat
Hospital. Madrid. Spain. Architect: Raphael Moneo
3-D view showing flexibility of stick glazing to allow discontinuity of capping pieces
MC H
123
- - -Walls 02'- - - - - - - - - ----. Glass systems 2: unitised glazing Details I. Extruded aluminium transom
2. Extruded aluminium mullion 3. Extruded aluminium section
4. Single glazed or double glazed unit 5. Rubber-based weather seal 6. Rubber-based air seal 7. Floor slab
8. Metal-faced or opaque glass-faced insulated panel
9. Floor finish 10. Ceilingfinish
\
3-D view of glazing panel assembly
Vertic al section 1:5 through unitised transom
3-D view of panel arrangement
MC H
124
Horizontal sectio n 1:5 t hrough uniti sed mullion
Detail of system assembly
Detail of frame assembly
System design as assist in internal drainage.The t erm semi-
gaskets which are pressed t ogether;either
of using prefabricated panels which are fixed
Unitised glazing is essentially a method
interlocking is also used for stick systems
in the form of'fli pper' gaskets or as com-
together on site to form a complete glazed
where large-scale frames, covering several
pressible hollow seals.These are made from
wall. Like stickglazing, unitised glazing uses
bays both vertically and horizontally are pre-
synthetic rubber; typically EPDM. Behind this
aluminium framing to support the glazing,
assembled in the factory and then lifted in
outer seal is a drained and pressureequal-
but where stick glazing is secured to a con-
place on sit e.The glass units and pressure
ised chamber closed off by an inner seal,also
tinuous supporting frame all of which is fixed
plates are then fixed on sit e as per regular
formed typically in EPD M.At the internal
on sit e, unitised glazing is put together in the
stick glazing methods.
face of the panel is an air seal. In hot and
factory.Panels are delivered to site and lifted
The double glazed units in unitised glaz-
humid climates, typically in South East Asia,
into place and set next to one another;the
ing are fixed to the supporting frame either
it is assumed that moisture will find it s way
gaps between each panel being sealed with
from the outside of the panel or the inside,
to the back of the supporting aluminium
synthetic rubber gaskets.These gaskets int er-
to suit the strategy for glass replacement in
frame. Consequently, seals are in horizontal
lock from panel to panel vertically, but typi-
the event of accidental damage.The double
joints to drain moisture from the back of the
cally are separated at each floor level with
glazed units are secured with pressure plates
system to the front face of the panel. where
a continuous horizontal gasket that follows
which are either mechanically fixed to the
it is released t o the outside. In more tem-
the horizontal joint between panels. Some
main frame, or form part of the frame itself
perate climates, unitised panels are sealed
systems have panels which are completely
An alt ernative method of fixing glass is to
in t he mid-depth of the framing,with the
separate structurally from the adjacent pan-
bond the glass unit s to a sub frame which
inner joint, visible from within the building,
els, allowing a damaged panel to be removed
is then mechanically fixed to the aluminium
serving as an air seal only.Any rainwater that
if damages occur; either during construction
frame.This method provides an all-glass
penetrates the outer seal is drained down
or later; but the junction between vertical
appearance on the outside, usual ly wit h a
through the inner chamberand is expelled
and horizontal joints requires special atte n-
recessed joint between panels giving a shad-
at the base of each unitised panel,typically
tion. Other systems are semi-interlocking
ow gap appearance betw een panels.
at floor level. Hor izontal joints between the
on horizontal joints in order to combine the structural capacity of members aswell
Vertical joint s between panels have an out er seal which is usually formed by two
t ransoms formed by the t op of one panel and the bott om of the panel above are
MCH
125
W alls 02 Glass systems 2: unitised glazi ng
~Ill
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Vert ical section I:25 through transparent panel
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® Vert ical section I:25 through opaque panel
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Details I. Extruded aluminium transom 2. Extruded aluminium mullion
3. Extruded aluminium section 4. Single glazed or double glazed unit 5. Rubber-based weather seal 6. Rubber-based air seal
====:!J
7. Floor slab 8. Metal-faced or opaque glass-faced insulated panel
I
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9. Floor finish
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10. Ceiling finish I I. Silicone seal wit h optional aluminium
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Elevation 1:50
formed in the same way, with seals aligned
sliding spigot joint set into the vertical joint
wit h those in the vertical joints to ensure
between mullions.This movement is taken
that rainwater is drained to the outside.
out horizontally in the horizontal joint, typi-
Unitised panels typically include at least one
cally at floor level.
additional transom to provide a spandrel
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MCH
126
In common with stickglazing,unitised
zone at floor level, for example, though
panels have thermal breaks set within the
some systems incorporate an additional
framing in order to reducethe transmis-
transom set against the inside face of the
sion of heat or cold from the outside of the
glass only, so that it is not visible externally,
frame to the inside, or vice versa. Since the
but provides a horizontal edge against which
inner ventilat ed chamber is typically deeper
internal ceiling finishes can be set.
than that used in stickglazing, the thermal
Panels are set so that they span from
Vertical section I:25 showing typical details
corner extrusion
break is positioned accordingly in order that
floor slab to floor slab, and like stickglaz-
the thermal break and double glazed unit are
ing, are either hungfrom a floor slab and
aligned.The overall width,or sight line, of the
restrained on the floor below, or are sup-
unitised panels is greater than those used for
ported on a floor slab and are restrained
stickglazing, from around 80mm to 120mm
on the floor above. Like stick glazing, move-
depending on the application.The greater
ment between panels is provided by a
width often suits the needs of internal parti-
3-Ddetails of corner connections
Horizontal section 1:5 through un framed corner
@
Horizontal section 1:5 through framed corner
tions which are required to intersectwith
made usually with a 45° angled mullion to
the framing members of the facade.
reduce the visual impact and sight lines of the mullion.
System details An essential aspect of unitised glazing
Parapet copings are formed by sealing and waterproofing the gap between the top
isthat the panels use the same perimeter
of the panel andthe parapet wall behind
framing, which can however be of different
with a synthetic rubber seal that is integral
shape and have different materials set within
with the panel.Thermal insulation is used to
them. Corner panels are the most common
provide a complete continuity of insulation
of the atypical panels, and are often the
from wall to roof.A metal coping is set on
most complex to construct in the factory. In
top of the panel to provide protection to
common with stickglazing, unitised panels
the membrane beneath. Elsewhere, most
can have vertical glass-to-glass joints rather
interfaces follow the principles of stickglaz-
than settinga mullion at the corner; provid-
ing, with an integral EPDM strip that can be
ing a visual crispness of the frameless corner.
fixed to project out beyond the edges of the
The unitised frame is stiffened internally to
panels, allowing the strip to be bonded to
compensate for the loss of structural stability
adjacent construction.
of the corner. Regular framed corners are
lAC headquarters, New York, USA. Architect: Frank Gehry & Studios Architecture MCH
127
Walls 02 Glass systems 3: clamped glazing Details I. Stainless steel patch plate 2. Single glazed or double glazed unit to suit applicat ion 3. Siliconeseal 4. Glass fin 5. Support bracket 6. Floor slab 7. Ceiling finish 8. Floor finish 9.Access ladder 10. Clamped glazed wall I I. Inner curtain walling 12. Maintenance access deck
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3-D view of wall assembly with detail of clamp (inset)
System design There are tw o types of'point fixed' glazing used for facades: clamped glazing and
facade system
MCH
128
joint s are sealed with si licone through the
bolt fixed glazing. Both syst ems are used t o
full t hickness of the joint typically with a pol-
increase the transparency of a facade,and
ymer-based backing rod in the mid depth of
this is parti cularly successful in open jointed
the joint. Clamped glazing was the first point
single glazing as used in double skin facades.
fixed glazing system used commercially and
W here double glazed units are used wit h
developed in the I960s, using metal plates
their black edge band and joints between
called 'patch plates' set on either side of glass
unit s, the width is usual ly equal t o that of
sheets at their corners.This techniques is
framed glazing, but the omission of framing
still used,t hough with increasing geometric
provides a visual continuity of glass where
complexity
transparency is required.The all-glass appear3-D detail of clampfixing in outer wall of tw in
surface. W here a sealed facade is required,
The clamped glazing system positions
ance has visual benefits to oblique views
the fixings holding the plates in place such
across a facade where the double glazed
that they pass through the joint s between
units are seen as a continuous uninterr upted
the glass to avoid the additional complexity
surface, made all the more dramatic by
and cost of drilling the glass. Becausefixings
changes in direction provided by corners,
are positioned at the glass edges, rather
as well as increasingly by folds in the glass
than within the glass itself, t he span between
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3-D view of twin wall construction with outer wall in clamped glazing
fixings is higherthan for an equivalent bolt
are formed by setting a synthetic rubber
fixed solution and glass thicknesses may be
gasket. typically EPDM, between the stain-
higherfor a clamped glazing solution as a
less steel plate andthe glass sheet. A bolt is
result.When used in a single glazed con-
passed through one sideof the plate and is
figuration in double skin facades, the glass is
secured into the other plate, usually with a
joined with clamps, plates and brackets, the
countersunk type.
preferred material is stainless steel due to
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Clamped glazing often uses glass fins to
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its resistance to corrosion.The use of plates
provide structural stability, set at 90° to the
allows a more complex geometry of glass to
plane of the glass, typically supported at its
be used, such as in a shingled arrangement
base on the floor slab. Glass fins are usually
of lapped glass panels where air can pass up
in lengths equal to the height of each panel,
through gaps between lapped glass sheets
with a patch plate connection occurring at
while admitting only small amounts of rain-
each horizontal joint of the glass, to form
water into the buffer zone behind. Glass can
a single structural section, wit h the dead
be supported either at the corners, or along
load of each panel transferred to the glass
its edges to suitthe supporting structure for
panel below, in the case of single glazing, or
the glass, which is usually visually lightweight
alternatively to the glass fin behind. Installa-
Vertical section I:50 through cable hung clamped
tions have reached up to around 15 metres
glass facade
in order to maximise transparency. Clamps
MCH
129
ails 02 Glass systems 3: clamped glazing @ Details I. Fixing bracket
1
2. Extruded aluminium mullions 3. Opaque glazing 4. Ground slab 5. Backing wall 6. Inclined and lapped glass 7. Cable support 8. Corner clamp 9. Cast metal fixing bracket 10. Clamp bracket
Plan and section 1:5. Clamping
I I . Metal parapet coping
configurations in cable hung
12.Thermal insulation
systems
I 3. Single or double glazed unit
Detail of lapped glazing connection Section I:I O. Opaque clamped glazed panels.Junctions at ground level, movement joint and panel-to-panel conditions
Rheinisches Landesmuseum. Bonn, Germany, Architect:Archtektengruppe, Stuttgart
Lapped, clamped glazing
Mediatheque, Sendai, Japan,Architect:Toyo Ito & Associates
MC H
130
Sectio n 1:5. Clamp and cable connection
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• 3-D view of co rne r clamped glazSection I:20. Clampe d
ing system
glazing with cast steel
Right: Elevation of cast stee l clamp
clamps held in place by forming part of a co ntinuo us t russ
is clamped to the glass unit above.
in height, though these are flat glass walls or
ings can be set at the corners of glass panels,
those forming vertical walls which are curved
where units intersect, or be set along t he
in plan. Glass panels and fins are joined with
length of joints.The choice of fixing position
accommodate higher amounts of structural
cleats and plates at the corner junctions,and
depends on both the geometry and size of
movement than an equivalent framed glaz-
are usually fixed through holes in the glass
the glazing.
ing system, which has encouraged t he use
rather than through the joints in order t o transfer loads effectively thro ugh the plates.
Clamped glazing is usually able to
of t ensioned cables, usually set verti cally, to
System details
which the glass is fixed. Cables are usually set
Clamping plates usually have a polished finish
Clamped glazing with glass fins is usu-
immediately behind vertical joints to reduce
for ease of cleaning, but brushed finishes are
ally set into a glazing channel at floor level in
their number and visibility, since plates offset
also used.
order to fix the glass in place and support its
from the vert ical joint require either an addi-
dead weight. A glazing channel also forms a
tional vertically-set cable, or a met al bracket
an economic method of fixingglass to a
reliable weat her seal with the outside ground
to connect the two patch plates back to a
continuous supporting frame behind the
level. Supporting glass fins which are sup-
single cable. In supporti ng cable structures,
glass joints as an alt ernative t o the capped
ported at floor level rather than ceiling level
which allow higheramounts of structural
This method of glazing has evolved into
glazing techniques of stick and unitised sys-
are usually set below floor level in order to
movement, doors are required to be set
t ems,with silicone seals set between the
conceal the patch plate brackets, which are
independently of the glazed wall,usually with
glazed units.This makes it suitable for facades
usually set either with the floor finisheszone
a metal frame around the opening which is
wit h complex frame design, particularly
or wit hin a pocket in the floor slab where
fixed at floor level only,and is structurally
when combined with a glazed roof that uses
this zone is insufficient ly deep.The same
independent of the glazed wall.
the same system.Triangular framed glazed
solution is used where the fin is hung from
walls, where the glass is required to have a
the ceiling. Clamp plates are also used for
smooth, continuous surface free of cover
doors to give a continuous appearance to
caps,allow clamps to be fixed through the
the facade. Doors are set typically on floor
joints between the glass directly back t o the
springs, set into the floor,and are supported
supporting structure set behind. Clamp fix-
at the to p of the door leaf with a pivot which
MCH
131
ails 02 Glass systems 4: bolt fixed glazing
Tower Bridge House, London, Uk.Architect:Rogers St irk Harbour + Partners
Details I. Caststeel connector
7. Bolt fixing
2. Mild steel or stainless steel
8. Stainless steel cable
angle bracket
9. Insulated panel
3. Single glazed or double
10. Floorslab/structural wall
glazed unit to suit application
I I. Bolt based cable end
4. Silicone seal
12. Glazing channel at floor level
5. Floor Finish
I 3. Structural column
6. Support bracket
14. Steel arm for lateral support
,
3-D overview of basic bolt fixed glazing system
MC H
132
Exploded view of bolt fixed componentassembly
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Vertical section I: 10. bolt fixed glazing detail
Detail of bolt fixing and 4 point glass connection
System details
System design Like clamped glazing, bolt fixed glazing is
(7)
be fixed back to tensioned cables or rods,
W ith both to p hung and botto m sup-
used for its ability to provide transparency,
allowing a visually lightweight supporting
ported methods of support , bolt fixed glazing
but usually with fixings set within the glass
structure to be used,but which requires lat -
uses a similar fixing bolt which is determined
rather than at their edges. In common with
eral stability to overcome the higher deflec-
by the size of the glass panel,the way it
that system, it was originally developed for
tions associated with cable stru ctures. Lateral
connects to the support ing structure and
single glazing, but is more commonly used
stability is usually provided by forming a
whether the fixing is countersunk or surface
with double glazed units, with their SOmm
vertically-set cable truss from the primary
fixed.The bolt fixing is the mechanical con-
joint width which includes the edge of the
cable supporting the glass unit s, or by adding
nection which is fixed through a hole formed
unit Despit e the overall SOmm black joint
horizont al outriggers from structural col-
in the glass sheet or double glazed unit. Bolts
width,the absence of framing and continuity
umnsto restrain the horizontal movement
can have a disc fixed to each external face
of the reflective surface of glass makes this
of the cables. In common wit h clamped glaz-
of the glass, be countersunk to be flush with
frameless system more visually lightweight
ing,glass fins or mild steel posts can be used
the outer face of the glass, or penetrate only
than framed glazi ng. Setting bolt fixings with-
to support the glazing,typically supported
the inner glass of a double glazed unit. St ruc-
in the glass can have an advantage in reduc-
from their base. Glass fins are fixed perpen-
tural movement and deflections betw een
ing the span of the glass between fixings,
dicular t o the vertical joints between glazed
the supporting structure and the glass are
ensuring that the glass t hickness is optimised
units,with an L-shaped bracket with a bolt
accommodated with a rot at ing swivel con-
t o a greater extent versus supporting the
fixing at each end, with glass panels stacked
nection at the junction of the bolt fixing that
glass at its edges only.
one above the other, using the glass fins to
passes through the glass and the end of the
Wh ere clamped glazing is supported
provide lateral support. Glass fins can also be
threaded rod that projects forward of the
directly onto a support ing structure, bolt
fixed at the t op of the wall or at ceiling level,
glass which is connected to the support ing
fixed glazing can be fixed on brackets which
where they serve as stiffeners in a down-
structure.The rotating joint is allowed to
are cantilevered away from the supporting
stand condit ion,wit h the glass still being
move 12° in all directions away from its regu-
structure, which can be either hung from
supported at it s base. Glass fins have clamps
lar posit ion.The bolt fixings t hemselves can
the top of the wall,or is supported at its
fixed t o them as per the pat ch plate system
vary from t hose with a fully visible thread and
base.These cant ilevered brackets can also
described in the previous section.
nuts, to a fully integrat ed type where all these
MCH
133
als 02 Glass systems 4: bolt fixed glazing
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Section I:I0 Glass panels supported on cables or rods
3-D overview of bolt fixed glazing system supported from cables
com ponents are co ncealed in sleeves. The bolt fixing is secured t o fixing brack-
Corner fixings are made eit her by cant ile-
it ed rotation at th eir fixing point has led to
vering th e meet ing panels out in each glazed
thei r support ing str uctures being structur ally
ets wh ose shape suit s th e geom etry of t he
wall form ing t he corner, and linking th e glass
ambit iou s, w it h a mixture of steel trusses and
inte rsection of four bo lt fixings with the sup-
panels tog ether w it h bolt fixings in a pin con-
cables used t o minimise the amou nt of mate rial needed t o support glazed units.Som e
porting stru cture . In small-scale applicat ions,
nection , or by int ro ducing structu re at the
fixing brackets can be formed from a simple
corner, wit h bo lt fixings being attache d t o a
have horizontally set w ind trusses t hat stiffen
steel angle, wit h one side supporting t he bo lt
primar y member.W here a corner bracket
an all-cable str uctu re, w hile others use full
fixing and the other side fixed to t he sup-
is used in conjunction with a cantilevered
height ver t ical steel trusses w ith additio nal
porting co lumn, or truss, for example. Larger-
junct io n, manufacturers increasingly provide
vertically set cables t o reduce the number of
scale applicat ions typically use X -shaped o r
a limit ed range of standard compo nents,
t ru sses required .T hey also pro vide a fixing
H- shaped con nectors to suit the po sit ion
t hough it is not uncommon for special con-
w hich is separat e fro m the seals betwee n
of bolt s set around the interse ctio n of fo ur
nections t o be provided, partic ularly fo r junc-
glazed unit s,though bot h bolt fixed and
glass panels. Connectors are made as eit her
ti on s w here th e meeting angle is not a right
clamped glazing methods have been pro ved
castings or machined/welded co mpo nent s
angle. Like clamped glazing, bolt fixed glazing
to be highly reliable in their weath erproofing
depending on th e quantity of connecto r s
is sealed between glazed panels w it h silicone
performance.W here clamped glazing is used
and t heir comp lexity.W here several parts
seals,providing a single barrier t o w at er pen-
wit h flat surfaces or glazed w alls of single
are required t o be w elded and machined, it
et ration, but one w hich is reliable if properly
cur vat ure , bo lt fixed glazing has t he possibility
is usually more eco nomic and visually prefer-
undert aken.
of being set on a surface w hich curves in two
able t o use a casting.
MCH
134
Th e ability of bolt fixings to provide lim-
direction s, as in th ose creat ed by cable net
3-D view of bolt fixed w all system
structures. Special care is needed to ensure
o
that the angles of incidence at joints provide
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Glass fixed
advantage is beingable to fix the glass that is
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Glass movable in one direction
visibly forward of the supporting structure, sometimes creating a visual contrast between large structural members and a thin glazed skin set forward of it.This is particularly used ifthe supporting structure is set in one primary direction,giving the appearance of the glass joints inthe opposite direction of span-
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Elevation I: IO. Fixing condit ions for typi cal bolt fixed wa ll
MCH
135
Walls 02 Glass systems 5: glass blocks and channels
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Maison Hermes,Tokyo,Japan, Architect: Renzo Piano BuildingWo rkshop
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3-D detail of glass blocks supported by box section
System design Glass blocks have been used in recent
panels,formed eithe r as open ings in walls
years for t heir qualities of robustness com -
o r as bays of a st ructu ral frame, typically in
bined w it h fire resistance t o form econom ic,
reinforced concrete or st eel.The cont inu-
t ranslucent, glazed wa lls,Their translucency
ous vertical and horizonta l joints of t hese
varies with t he thickne ss of t he w all of the
non-Ioadbearing panels give th eir charac-
individual glass block, w hich can range from
terist ic gridded appearance , w it h panel sizes
solid t o ho llow t ype,T he hol low ty pe has
limit ed fro m around 3600mm x 3600mm
the advantage of slightly greater t hermal
in area, to aro und 4500mm x 4500mm in
insulation and acoustic insulati on, but the
area, depe nding on block thickness.The
th ermal insulation levels are we ll below
panel size can be adjusted in prop ort ion to
th ose expecte d from regular do uble glazed
give a maximum height of around 6000mm
units, so they tend to be used in locat ions
and a maximum width of around 7500mm,
w here this is not a design considerat ion , such
Glass blocks are well suited to pro viding an
as in naturally ventilat ed spaces,T he most
econo mic glazed fire resisting construction,
common block sizes are a nomina l 200mm
One hour fire resisting panels can be made
x 200mm and 300mm x 300mm, generally
in panel sizes of aro und 3000mm x 3000mm
I OOmm th ick, Blocks are arranged in stack
in area,w ith a maximum height or w idt h
bonded rectili near grids th at fo rm individual
of 4000mm. Panels providing fire resistance
3-D view of glass bock wall assembly
MCH
136
Examples of glass blocks in curved applications
3-D sectional detail of glass blocks supported by I-sections
greater than 60 minutes (usually up to 90
glass blocks.An advantage of glass channels is
minutes) require metal channel restraints
that they are made either with a patterned
at the perimeter of the panel due to their
surface characteristic of casting, or be made
greater reliability than cement mort ar or
clear, with no pattern or hue.They can be
si licone seals.
Low-E coated to assist thermal insulation,and
200!300mm
An alternative to glass blocks is cast
when interlocked can be thermal ly insulated
glass channels, a long spanning material which
with proprietary gel to significantly improve
can reach storey height without intermedi-
their thermal perfor mance,though this proc-
ary supports. Channels resemble half glass
ess can be disproport ionat e to the cost of
blocks in section, manufactured in lengths up
the cast glass channels. Solar protection can
to around 7000mm. Most are made around
also be added. Like glass blocks, cast glass
250mm wide and 60mm deep. Channels
channels are known for their properties of
3.Metal edge frame
are set either vert ically or horizontally in a
sound insulation combined wit h robustness.
4. External cladding
single layer, or can be int erlocked by setti ng
W hen st acked vertically, channels can be set
5. Steel fiat or T-section
channels facing one another to form a dou-
out to form a curved wall, a characterist ic
ble layer with smooth internal and external
well known with glass block walls.
appearance.The int erlocked version also provides a U-value similar to that of hollow
Typical glass block dimensions
Details I. Glass block
The relatively poor thermal insulation of glass blocks and cast channels,when
2. I-section or box section
6.Thermal insulation 7. Enclosing wall or adjacent wall 8.Window casement 9. Cast glass channel IO. Floor slab
MCH
137
Walls 02 Glass syste ms 5: glass blocks
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Det ails of glass block connections w ithin window casement
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3-D view of glass blocks set within window casement in w all assembly
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Ho r izontal section I : IO. Connection to
H or izont al section " I O. Connec t ion to
alternat ive wall buildup
supporting structu re
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MC H
138
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Horizont al section I: IO. Glass blocks support ed by w elded sect ions
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Elevation and section I:20. Glass blocks supported by box sections
3-D view of typical glass panel vert ically hung
Section I:20 Left: double skin of interlocking glass horizontal channels. Right: Single skin
compared to double glazed unit s, can lead
combination of these. In smaller openings, a
silicone-based or with metal angle restraints.
to condensation occurring on the interio r
T-section is set into joint s to stiffen the panels
The angles are usually concealed by wall
face of the block,and adequate ventilation
at mid height between floor and ceiling/sof-
finishes, both internally and externally. Flex-
is requiredto avoid this. Consequently,their
fit. Larger panels can be formed by adding a
ible seals are used where a door or window
use remains ideally suited to semi-external
rectangular box section to the backedge of
opening is introduced int o a glass block wall.
conditions in temperate climates, such as cir-
the T-section to form a complete structural
The door is usually fixed at its base only in
culation spaces. Glass block panels fixed into
frame. Some manufacturers offer these mate-
order to allow the block wall t o be structur-
reinforced concrete frames or wall openings
rials as proprietary systems which include
ally independent. but sometimesthe door
are bedded in either mortar or silicone,with
edge framing channels, thoughthe appear-
is tied into the horizontal joints of the glass
flexible joints introduced on the sides and
ance of these can be concealed by adjacent
block wall, depending on the amount of
top edge to allow for structural movement.
finishes.
expected structural movement.
Glass blocks are set within the frame which
Glass blocks usually have bed reinforce-
Cast glass channels are fixed into alu-
formsthe external wall,or on the edge of
ment between joints,typically a metal ladder-
minium extrusions at their ends, and are
reinforced concret e floor slabs. Storey height
type reinforcing strip which is set within the
sealed with silicone-based seals between long
panels on the edge of floor slabs require
joints and is not visible. Silicone is also used
joints.vertically-set channels can be bottom
metal angle restraints at the top of the open-
to bond blocks, with a sealing silicone used
supported, but in horizontally-set arrange-
ing to accommodate the deflection in the
on the external face to provide a weath-
ments, each channel is individually supported
slab.This can be overcome by setting the
ertight seal.Cement-based mortar s are
rather than each channel being supported on
glass blocks forward of the floor slab on a
also used, with the choice of material being
the channel below.As with glass blocks,the
steel frame in the manner of glazed curtain
governed largely by visual considerations.
edge frame can be concealed by wall finishes,
walling.
Corners are formed usually with either the
but cast channels are increasingly being used
structure that supports the panel or special
as a primary material on facades where they
corner panels which form a part of most
are used, as they are not required to be set
System details
proprietary systems, mainly 90° and 45°
into framed panels, and can be used in storey
also be set into steel frames made from
Both glass blocks and cast channels can
corners.Junctions of blocks with adjacent
height form in long lengths.
I-sections, box sections,T-sections or a
walls are formed with a flexible seal, either
MC H
139
---
W alls 02 Glass systems 6: steel windows Det ails I. Outside 2. Inside
3. Rolled steel glazing section 4.Transom 5. Mullion 6. Single glazed or double glazed unit to suit application 7. Fixing bead 8. Fixing lug 9. Projecting transom 10. Rubber-based seal I I. Fixed light 12. Inward opening light I 3. O utward opening light 14.W indow cill 15. Condensation tray 16. Internal finish
Matsunoyama Museum of N atural Science. Matsunoyama.Japan.Architect:TezukaArchitects.
@ Plan I:S. Rolled steel frames glazed Intemally
@
Rolled steel glazing connection detail
Plan 1:5. Rolled steel frames glazed externally
System design Steel framed windows made from rolled sections have been preferred for their thin sight lines when compared to those in alu-
aluminium-based stickglazing. Steel framed windows with thin frames without thermal breaks in thin double glazed
glazed units usually have extruded clipsthat hold the glass in place. Larger scale,thermally broken, windows
minium for small-scale window openings.
units are madewith rolled steel sections to
and doors are used primarily for their ability
However, the thermal performance of the
form windows of a maximum size of around
to provide fire resistance.They are made as
frames is considerably less than thermally
3000mm x 1800mm down to a minimum
pressed steel sections in sizes similar to an
broken aluminium sections, due to the dif-
size of 250mm x 400mm. Fixed lights and
equivalent in aluminium but with slightly dif-
ficulty of intro ducing a thermal break int o
openingwindows can be joined together
ferent profiles governed by the process of
small sections. Larger scale steel windows
withT-sections to provide a supporting
pressing,which cannot provide the complex-
and glazed walls made from pressed steel
frame. Larger-scale steel curtain wallinghas
ity in section of extruded aluminium profiles.
sections, used mainly for their fire resisting
a grid of pressed steel mullions (verticals)
Unlikealuminium windows, where new extru-
qualities, can incorporate a thermal break
and transoms (horizontals) to which double
sions can be made economic for each project,
but their sightlines are similar to those of an
glazed units are fixed with steel pressure
pressed and rolled sections for steel windows
equivalent aluminium window or glazed wall.
plates. Seals are provided with synthetic rub-
cannot produce new sections as easily. Fully
Steel framed windows are either fitt ed into
ber gaskets similar to those used in alumini-
glazed walls are made by fixing individual
wall openings or are joined together to form
um curtain walling systems. Single glazed units
windows into a frame of pressed box sec-
a glazed wall with deeper sections as fram-
have small channels or angle shaped glazing
tionswith integral thermal breaks.There is a
ing members, which is slightly different to full
beadsto hold the glass in place,while double
wide variety of standard sectionsavailable for
MCH
14 0
De t ail of pro ject ing mul lion in st eel glazing
Matsunoyama Mu seum of N at ural Science. Mat sunoyama, Japan. Arch itect: Tezuka Architects.
~ ~
@
Fixed bead with proj ecting
transom :
@
Sect ion s 1:5. Rolled ste el frame s glazed int ernally and exte rnally
th e pressed steel profi les th at support t he Opening
glass, th ough it is more difficult t o develop a
w indow with
pro file for an individual project due t o t he
projecting transom
constraints of pre ssing steel sheet, w hich is expensive to modify for individual pro jects.
Syste m details Outward ope ning lights for bot h w indows in small-scale rolled sections and larger-scale pressed sections have profiles that lap over t he front of t he surrou nding fixed frame, w ith a drip above the wi ndow t o avoid rainw at er finding its way in through th e top of t he
G il detail
frame.A ny water t hat finds its way into t he frame is drained dow n t he sides and out at the bottom. Most win dows have synt hetic rubber seals to both assist drainage and reduce air infilt rat ion t hro ugh t he open ing
3-D view of ro lled steel wi ndow details
MCH
14 1
W alls 02 Glass systems 6: steel windows
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Sections 1:5 of pressed steel doors with thermal breaks. Left: Outward opening. Right: Inward opening
Vertical sections 1:5. Sliding/foiding door with rubber seals
Section 1:5 Pressed Steel window,thermally broken
light. W ith inward opening lights the top of
and glass types. Steel framed windows and
ness where rolled sectionsare used,and with
the window is protected by the top transom
doors are also made as separate itemsfor
thicker horizontal sections in doors where
of the fixed frame.The window is more vul-
glazing into openings in masonry walls. In this
pressed steel sections are used. Corners are
nerable at its bottom edge where it is pro-
instance they are fixed through the frame into
framed with either glazed or glass-to-glass
tected by a projectingcill. W ith steel windows
the adjacentstructural wall.An EPDM foil or
corners in the manner of aluminium curtain
made from rolled sections, any water pen-
silicone sealant is then used t o seal the gap
walling but where the glazing is fire resistant,
etratingthe outer seal runs around a groove
between the steel window/door andthe adja-
panel sizes are limited.Those in small-scale
cent concrete or masonry wall.
rolled sections are formed with eitherT-sec-
in the frame of the opening light and down the sides into the bottom transom below,
Larger-scale glazing has framing with a
tions that meet to form a recessed corner,
where it is drained through weep holesto
continuous indented groove that forms a
or with a square-shaped hollow section t o
the outside.This is similar to the principle
channel into which toggle-type fixings are
form a solid corner. Corners using larger-
of traditional timber windows, but windows
inserted to receive the fixingsthat secure the
scale pressed sections are formed in a similar
made from thermally broken pressed sec-
pressure plates.The synthetic rubber seals, on
way to stickglazing,with mullion profiles set
tions can follow the principles of aluminium
either side of the glass provide a sealed cham-
t ogetherjoined by a thermally insulated panel
framed curtain walling,with a ventilated and
ber behind the pressure platewhich is used
on the surface of the glass.Some manufactur-
pressure equalised chamber behind the outer
to drain away any wat er that penetrates the
ers provide standard corner sections as part
seal which drains moistureaway and backto
outer line of defence.Thisvoid is ventilat ed,
of a proprietary system. Parapets are formed
the outside at the bottom. Opening windows
with transoms draining water at the base
by fixing a folded metal coping into the top
and doors are set into steel framed glazing
of each glazed unit using a synthetic rubber
transom and folding it over the parapet
with an addit ional frame which is visible from
strip that slopes down to drain water to the
behind. Metal fiashings with an EPDM foil
the outside, a principle which is followed in
outside.
aluminium windows and glazed walls. Door
For both small-scale rolled sectionsand
and window lights are formed from pressed
larger-scale pressed sections, doors are con-
steel sections which are folded together to
structed in the same way as windows, but
form a family of profiles to suit different sizes
wit h horizontal rails to provide greater stiff-
MCH
142
behind it are also used to seal steel glazing against areas of adjacent walls, typically of masonry or concrete construction.
3-D view of pressed steel windows thermally broken
Profiled mullion detail
Details I . Pressed steel frame 2. Pressed steel glazing bead 3 Double glazed unit 4. Insulated steel panel 5. Rolling wheels 6. Guide at bottom of door 7. Rubberbased seal 8.Thermal break 9. Pressed steelpressure plate IO. Pressed steel glazing section
Details of alternative cappingprofiles for angled glazing and corner conditions
MCH
143
as 01 Glass systems 7: alumini um windows
(j)
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(
3-D view of opening window set into large scale aluminium window assembly
Vertical section I:5. Opening window detail
System design Win dows made from aluminium are
over those in other materials is their useof
an air seal rather than as a full weathertight
formed either as individual frames set into
extruded profiles which can take up com-
seal.An additional function of the gasket seal
structural openings or are set in groups to
plex shapes in section t o which thermal
is t o provide a continuity with the thermal
form a complete glazed wall where indi-
breaks and seals can be fixed with ease,and
break so that the air temperature of the
vidual lights are linkedt o givethe appear-
within which water can be drained with a
inner chamber is much closert o the internal
ance of an overall modular glazed facade. A
high level of precision.This allows aluminium
temperature than the externalt emperature.
glazed wall, formed as a large scale window
window framesto be relatively well thermal-
Where window frames tend to be
assembly is used typically where the glazed
ly insulated,and have low rates of air infiltra-
narrow and deep in section, in order to
wall is not of sufficient size t o require it to
tion when compared t o other materials.The
accommodate the seals andthermal breaks,
be supported or hung from floor to floor;
main disadvantage,from the visual point of
doors are usually wider in order to provide
which is the principle of stickglazing and
view, is the wide sightlines required for struc-
greater stiffness for the glazed units which
unitised glazing in curtain walling. In contrast
tural reasons in accommodating seals for
they support. Doors were not usual ly ther-
to curtain walling, which is a structurally
int ernal drainage and thermal breaks.Whe re
mally broken until recently, since rigidity and
independent external wall,'window walls'
sightlines are reduced,the overall depth of
durability of the frame is usually the most
have windows fixed onto a structural frame
window is increased to compensate for the
important consideratio n,but t hermal breaks
or backing wall, which is set into a larger
loss of stability of the frame. In common
are becoming much more common in door
structural opening in a facade.Windo w walls
with aluminium curtain walling, extruded
sections. Doors with lower air infiltration
provide the appearance of a curtain wall
aluminium window frames are pressure
rates and a thermal break are made from
combined with the acoustic and fire resist-
equalised and int ernally drained in order t o
window sections rather than door sections.
ing properti es of its backing wall,making it
provide two lines of defence against rainwa-
The increased performance usually results
suitable for apartments, for example.W in-
t er penetration.An outer seal,typically a syn-
in smaller maximum door sizes, at around
dow walls are typically supported at their
t hetic rubber gasket, excludes most of the
2400mm for a thermally broken, internally
base, but can also be top hung or side hung
rainwater;but any wat er that passes through
drained and ventilat ed door. Doors with
is drained away at the bottom of the profile
thermal breaks can reach a maximum of
to the outside.The internal barr ier serves as
around 3000mm to 3500mm wit hout wide
depending on their geometry An advantage of aluminium windows
MCH
144
(j)
(j)
CD
CD
Elevation I : I0, Opening w indow set w ithin large scale aluminium wi ndow sectio n
Vert ical section I : I0, Outw ard opening aluminium w indow
II II
Horizontal section I : I 0, O utward openin g w indows set w it hin large scale w indow assembly
JJ ,",~==== CD
Horizontal section I : I 0, Ou tward openin g wi ndow set t ypical wall construction Vert ical section I : I0, Outward opening aluminium w indow set w ithin t ypical w all construction
Details I , O utside 2, Inside
3.W indow frame 4, Single glazed or double glazed unit to suit applicatio n 5, Ext ruded aluminium section e.Th erm el insulation 7,Timber battens for decoration 8, Opening mechanism 9, Surro unding wall 10, Insulated composite panel I I Flo or construction 12, Roof construction
3-D view of aluminium framing system for large scale w indow wall.
MCH
145
W alls 02 Glass systems 7: aluminium windows
3-D view showing construction of aluminium framed winow wall system
sightlines. Doors with thermal breaks can
opening light, then that shading function is
struction.The EPDM-foil seal is used where
exceed 2400mm high by silicone bonding
largely maintained when the window is in
the window is fitted first, since the surround-
the glass to the frame so that glass assists in
the open position.Thesewindows also help
ing wall must be clear in order to fix it, and
st iffening the frame.The maximum width of
smoke evacuation where used as smoke
a perimeter seal is usually used where the
doors is a function of their height, in order
vents, but an essential characteristic is visual,
window is fitted after the adjacent external
to restrict the overall weight, but a 850mm
in having opening lights in glazed walls which
wall has been completed.
wide door leaf forming a 1700mm wide pair
do not interrupt the visual continuity of
of doors is not uncommon. Minimum width
the overall facade design. Parallel opening
used, opaqueglazed infill panels are set
W here aluminium window walls are
of opening lights is about 250mm where a
windows use a scissor-shaped hinge which
between window panels as a facing to the
double glazed unit is used. Minimum heights
slideswithin the frameto provide a stable
insulated backing wall arranged immediately
of glazed vent ilato rs, such as those set above
support for the open window in any posi-
behind. Metal infill panels are also used,
door s for night time vent ilation,are around
ti on.These opening light s are used with win-
sometimes in rainscreen configurat ion,
250mm to suit the needs of the opening
dows that use stickglazing sections used in
but more typically sealed in a support ing
mechanism. Side hung,top hung,bottom
curtain walls, particularly where the double
framework.W here opaque panels are used,
hung and tilt/turn windows use similar alu-
glazed units are silicone bonded to reduce
opaque panels are fitted to a simple support
minium profiles.
the visual impact of their support ing frames.
as required by rainscreens and composite
W indows and doors are sealed at their
panels rather than a full window wall fram-
System details
int erface with the surrounding walls usually
ing system. In this window wall configuration,
A recent development has been the
with a synthetic rubber strip which forms an
windows are set forward of the opening
introduction of parallel opening lights, where
integral part of the window frames, or alt er-
where the complete facade is required to
windows open in a direction parallel to
natively with a seal betw een window frame
be in a single plane, rather than within the
that of the frame.This has an advantage of
and opening,typically with a silicone-based
opening itself.The gap between window and
increasing the amount of air that is admit-
product. Some synthetic rubber seals have a
opening is closed with metal flashings, which
ted without exposing a complete section of
metal facing for addit ional protection, called
can be concealed with internal finishes.
wall to the effects of both wind and solar
a 'foil',which is bonded t o the adjacent wall,
radiation. If solar control glass is used in the
and is usually concealed by the adjacent con-
MCH
146
3-D detail of aluminium frame in typical window w all system
3-D view of typical w indow w all system
3-D det ail of w indow w all connection to fioor system
,.
CD
Ho rizont al sections 1:5 t hro ugh aluminium win dow wall system showing typic al panel and window details
CD MCH
147
Wa fs 02 Glass systems 8: timber wi ndows
:r II
II
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3-D sect ion through t imber frame top hung w indow
Section 1:5 Ver t ical sliding sash wi ndow
Details I.W indow frame 2. Outside
3. Inside 4. Head S.Ci ll 6. Single glazed or double glazed unit to suit applicat ion 7. Fixing bead 8. Rubber-based seal
Old N icho l St reet, London, U K Architect Maccreano r Lavingto n Architects
MCH
148
3-D section through side hung w indow det ails showing different framing methods
Horizontal section I :5. Sliding sash w indow s
System design In common w it h aluminium w indows,
t ion to avo id being expo sed to the effects of
of the w indow wa ll.
t imber w indows are used either individually
t he w eather. In addition, the high mo isture
w ithin w all openings or are gro uped t o form
movement associated wit h t imber makes t he
span up to two floors, typically restricted by
a comp lete 'wi ndow wall', formed by linking
penetration of the steel supporting struc-
the self w eight of t he panels,w hich are usu-
w indows into a cont inuous arrangement.
t ure through th e exte rnal face of t he t imber
ally suppo rt ed at th eir base.This is due t o the
They are supported by an integra l timber
glazed wa ll more difficult to w at erpro of
need to t ie the frame into large single units
T imber framed w indow wa lls ty pically
frame, typ ically reinforce d interna lly by steel
W here w indows are linked and reinforced
t o avoid t he effects of th er mal movement of
flats o r sometimes supported by separate
wit h a mild steel flat , a drainage gro ove set
th e sections. If timber section s are not t ied
secondar y steel supports in the form of col-
int o the joi nt ensures th at any wat er th at
together; t hey tend to w rap and twi st wh en
umns or complet e frames.W here individual
penet rates t he oute r joi nt is drained away
exposed t o outside elements. Even if t he
w indows are linked together w it h t hin steel
to the outside at the bottom of t he win dow
surfaces are painted or sealed wit h varnish,
reinforc ing plates,the panel size is limit ed t o
or wi ndow w all. Drainage channels are used
any movement due to moist ure wi ll crack the
storey height, and the w indow wa ll arrange-
on all four sides of th e w indow in t he man-
outer finish and allow further moveme nt to
ment is fixed back to th e suppor t ing struc-
ner of aluminium curtain wa lling.The steel
occur.Timber sectio ns are jointed w it h either
tu re of floo r slabs or supporting w all.Where
stiffening rib or br acket does not extend for-
t ongue-and-gro ove o r rebated joint s.Where
t he visual presence of timber framing mem -
w ard of th e dr ainage gro ove to allow w at er
to ngue-and-groo ve joint s are used,the linking
bers is not the preferred expre ssion of the
to be drained away unimpeded. Mullions
material can be a durable hardwood or alu-
facade from the outside, a secondar y steel
and t ransoms (verticals and horizontals) may
minium. Sections can also be bolted together
frame can be set interna lly, ty pically made
be of different depth to suit their individual
if t he sections are of sufficient size, such as
from tu bes,T-sections or box sections to
structural requirements and may be in a dif-
around 75 x 50mm .
reduce th eir visual impact.A lternative ly, th e
ferent wood. Hardw ood s and softw oods can
steel component s can be set w it hin timber
be mixed in a single wi ndow wall construc-
members form ing th e supporting frame t o
t ion, but t he relative mo isture mo vements
System details Inw ard openi ng w indows are inherently
the w indow wa ll, depending on the required
associat ed with each type is taken in account
vulnerable to wat er penet rati on at th e bot-
sizes of the steel member s.These steel com-
to ensure t hat th is movement do es not
tom of t he fram e, whi le outward openin g
ponents are set w ithin t he t imber construe-
adversely affect th e appearance o r stability
frames are w eaker at the head of t he frame.
MC H
149
Walls 02 Glass systems 8: timber windows
o =z;=~~~_ 0
Section 1:5 Sliding doors
Section 1:5 Outward opening casement windows
-
3-D view of timber doors and windows in wall syste m
MCH
I SO
!
-=::::::::-----
-
--------....---::... ::::-.. -
--
CD
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Horizontal section through timber sliding doors
Elevation 1:5 Sliding doors
For this reason,drainage channels are provid-
window during manufacture and are sealed
mon frame design is used for different hinge
ed within the frames, together with weather
against the surrounding wall.There has been
arrangements in openinglights, which gives
seals and weather bars. Like aluminium win-
an increased control of moisture movement
a harmonious appearance to window walls
dows, timber windows usea single section
of the timber used with better controlled
with lights that are required to open in differ-
for all four sides of an opening light, and a
kiln-drying. Treatmentsto timbers are also
ent directions.
single section for three sides of the frame,
changing to avoid toxic runoff while provid-
with the cill being different to drain water
ing some protection against colour fading
against adjacent wall construction wit h metal
away from the window.Timber windows can
from UV radiation from sunlight. Some more
flashings which can be formed either as an
achieve relatively low levels of air infiltration
economictimber windows have traditionally
integral part of the window frame, or alter-
and have vastly improved in their weather
suffered from poor jointing at the corners of
natively be fixed to it with synthetic rubber
Timber glazed walls can be sealed
performance in recent years, primarily as a
the frame.These have been improved across
based seals mechanically fixed to the frame.
result of the useof synt hetic rubber seals and
all window types in recent years with the
Corners can be formed with either a timber
aluminium weather bars.W eather tightness
use of double mortise and tenon joints and
post forming the corner or as a fully glazed
has been enhanced by the use of pressure
wood glueswit h better resistance to heat
junction.Where transoms meet at a corner
equalised rebates in the window section so
and moisture.W here timber windows are
without the benefit of a mullion (vertical)
that any water passing through its outer seal
set into an openingrather than being part
the junction is usually joined with a toothed
is drained away without being drawn through
of a window wall, the most common materi-
junction to ensure that no visible move-
by capillary action asa result of an air pres-
als used are masonry block, brick or timber
ment occurs.The full interlocking connection
sure difference between inside and outside
boarding.With all these materials,timber
between components in these exposed
the framing. The inner synthet ic rubber seal
windows are fixed either into the reveals of
conditions is vit al to the success of timber
also serves as an acoustic barrier. providing
the opening or are fixed into the face of the
glazed walls.
improved sound insulation. Seals between
opening.The position of the window in the
the window and the opening have been
opening has more influence over the junction
enhanced in recent years with the increased
with the surrounding wall than the choice of
useof folded aluminium and UPVC profiles
material for the wall. In proprietary ranges
which are set into a groove around the
of windows from manufacturers, a comMCH
151
ails 02 Concrete I : cast in-situ
D etails I. Conc rete exte rnal wall 2. Co ncrete internal wall 3. Met al lining t o gutter 4.Window fram e 5. Slot formed as part of casting conc ret e. 6. Met al parapet fiashing 7. Single glazed o r do uble glazed unit t o suit applicat ion 3-D view of concrete cast-in-
8. Met al cill, th ough precast
place panels in st ructure
conc rete cou ld be used 9. Int ernal floor slab 10. single conc ret e wall I I. Thermal insulat io n
System design ture within the building as well as prevent
tion,the two linked concrete walls are joined
pouring it into a shape created by formwork
the concrete surface from being seen inside
structurally by concrete ribs which form
makes its construction quite different to
the building.An important development in
limited thermal bridges, or alternatively are
The method of forming concrete by
working with other materials.While metal,
recent years has been an increase in the
linked by stainless steel ties.The use of metal
glass, timber and masonry are made in rela-
provision of thermal insulation set typically
ties reduces the thermal bridging with its
tively small panel and unit sizes, concrete is
within the depth of the construction,allow-
associated risk of condensation and pattern
restricted only by the available formwork
ing the external face to have a visible con-
staining forming on the inside of the wall in
and the amount that can be poured at one
crete finish.
temperate climates.
time.The useof in-situ loadbearing con-
Setting thermal insulation within the wall
An alt ernative method of constructing an
crete walls asa facade system exposes the
allows the thermal mass of the concrete to
in-situ castconcrete wall is to set the thermal
castconcrete asa surface finish.This is in
contribute to night-time coolingas part of
insulation on the inside face of the wall, but
contrast to the useof in-situ loadbearing
an environmental design strategy. Continu-
this results in the loss of the wall'sthermal
walls as backing walls to a different facade
ity of thermal insulation at the interface of
mass.This method has the benefit of econo-
system, where the function of the wall is
concrete and glazed openings is increas-
my. especially where there is no requirement
only as primary structure, while the external
ingly important in order to avoid thermal
for night-time cooling.
skin is non-Ioadbearing cladding.The use of
bridging. In this method of construction,
System details
in-situ reinforced concrete as a self-finish to
diaphragm walls are used with two walls
external walls was popular in avant garde
linked structurally being set either side of a
architecture throughout most of the 20th
rigid thermal insulation core.This allows part
or slightly sloping surfaces such as window
century. but walls were constructed without
of the concrete structure to remain closer
cills are washed off during rain and can be
thermal insulation within the wall depth.
to the internaltemperature of the building,
deposited on the wall below. Consequently.
Instead, insulation waseventually added on
and benefiting from the thermal mass of the
openings, parapets and cills in exposed con-
the inside face of the wall, which both pre-
primary structure as well as permitting the
crete walls have projectingcills and flashings
vents the thermal mass of the concrete wall
internal face of the building to have a visible
to ensurethat rainwater is thrown as clear
from being used to regulate the air tempera-
concrete finish. In diaphragm wall construc-
as possible from the external wall surface. In
MCH
152
Dust particles that settle on horizontal
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Section I:25. In-situ cast concrete wall cast intwo skins with rigid closed cell insulation between skins
CAC Museum Cincinatti, USA. Architect: Zaha Hadid Architects 3-D view showing roof parapet and window details witin cast-in-situ concrete wall system
MC H
15 3
W alls 02 Concrete I: cast in-sit u
.0 . '1'
3-D view & horizontal section I:I O. Concrete wall: Insulation set within wall
Tod's building,Tokyo,Japan. Architect: Toyo Ito
3-D view & horizontal section I:I O. Concrete wall: Insulation set on inter nal face
urb an cond ition s,dust-catch ing surface te x-
wit h grey being associate d w it h archit ectural
associate d w it h pigment addit ives. Smooth
tures are usually avo ided and sm oot h finishes
concre te finishes w hich usually pro vide a con-
and visually consistent natura l finishes are
are often preferred. H ow ever,where protec-
sisten t appearance, when po uring methods
achieved largely by both th e accuracy of
ti ve treatments are applied t o th e external
and condit ions remain con sistent during co n-
mixed proportions including water.
surface of t he concre te t o reduce porosity,
structio n of th e facade.Th e t on e of grey wi ll
Textured finishes can be achieved w it h
th is can give a reflect ivity to the mat eri al th at
vary w it h the cementJw ater rat io, th e poros-
specially formed shuttering boards o r wit h
reduces it s characteristic stone -like appear-
ity of th e shuttering, vibrat ion con ditions,
an addit ional lining sheet containin g th e
ance.
fo rm work stripping t ime and weat her cond i-
t extu re pattern. Polystyrene (one t ime use)
t ions.W hite cement is much more t o lerant
or synt het ic rubb er sheet (multi ple use) are
are cast int o the t op s of win dow reveals
of variat io ns in methods and sit e co ndit ions
commonly used. Recessed joints are usually
t o reduce bot h staining t o t he soffit and to
in providing a consistent w hit e colou r.
introduced betwee n the formwork boards
Drips in t he fo rm of continuou s grooves
reduce t he amou nt of w at er reaching th e
The mo st common finishes fo r concret e
t o avoid uneven and blurred lines at t he
wi ndows . Cills are usually formed wit h a
w alls cast in-sit u are eit her an as-cast finish o r
junction between bo ards.W ashed finishes
metal sheet apro n that helps th row w at er
a w ashed finish. Other finishes are discussed
are formed by applying a deactivat or t o th e
clear of th e w all below, w hile metal copings
in th e sect ion on precast panels: acid etc hing,
exte rnal face of t he concrete, eit her to t he
are usually inclined in o rder t o drain w at er
sand blasting, t ooling and polishing,though
face of the fo rmwork befo re casting or to
ont o the ro of or gutter behind rat her th an
the se addition al finishes can be used on in-
th e co ncret e surface w hen t he fo rm work
dow n th e face of the concrete w all.
sit u-cast concrete .W ith as-cast finishes, t he
has been removed.The deactivator is used to
colo ur variat io ns result not usually from t he
slow down or stop hydration of th e cement,
bearing concrete wa lls is influenced mainly by
cement co lour, but rather from the marbling
and is applied by br ush or spray.T he con-
th e choi ce of ceme nt, w it h fair faced visible
effect of fine particl es of sand becoming
cret e is th en sprayed w it h w ate r or aqueo us
concret e wa lls using either grey or w hite
unevenly distr ibuted during vibrat ion w hen
acid so lut io n to remove the surface, revealing
cement bases to prod uce t he surface colours
t he concret e is po ured in place. Smooth
the mater ial below.
The colour of concrete for in-situ load-
associated wit h each.The physical prop erties
co ncrete is ty pically self-coloured in large
of t hese two cement ty pes are very similar,
areas of facade t o avoid colour variat io ns
MCH
154
Photos illustrating texture that can be achieved through in-situ casting
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Int ernal w all elevation I :50 In-situ cast concrete w all w it h textured effect as above right
Timber/Aluminium form work on upper fioors of building construct ion
Timber form work used t o achieve texture
Elevat ion 1:50 In-sit u cast concrete w all showing how form work can be arranged and cut to form different shaped panels and windo w openings
MC H
155
W a ls 02 Concrete 2: storey height panels
HousingVillaverde, Madrid,Spain. Architect: Chipperfield Architects
3-D view of wall assembly
System design The method of casting in-sit u walls
rather than glazing individual openings
suit road transportation, with a maximum
described in the previous section is one
associated wit h full height precast panels.
weight of around 10to nnest o suit regular
of forming loadbearing construction. With
Non-Ioadbearing precast cladding panels
site cranes. As with in-situ castconcrete
precast panels, walls can be formed as either
typically span from floor to floor; with panels
walls,the thermal insulation can be set either
loadbearing walls or as cladding panels to
supported either directly on the floor slabs
on the inside face of the panels or within
a structural frame. Loadbearing types have
or set forward of them, fixed back to the
a diaphragm wall construction. Panels are
storey height panels'stit ched' together to
floor structure with brackets madetypically
manufactured in flat moulds, with the fin-
become integral with the floor slabs.Junc-
from stainless steel or reinforced concrete.
ished face at t he bottom of the mould when
tio ns are usually pin jointed, wit h structural
The method of fixing panels is very depen-
the concrete finish is required to be visible,
stability provided by other components such
dent on both spatial requirements within
or with the finished face on the top of the
asservice cores elsewhere in the building.
the building and whether concrete nibs can
mould where another material is applied
Precast panels may have a decorative fin-
remain a visible part of the panel design or
such as ceramic tiles, or where metal fix-
ish on one side, with thermal insulation set
are required to be concealed within the
ings for a masonry finish are castinto the
within the panel,or may be used asa back-
internal finishes. St orey height panels can
face of the panel.Where a concrete finish is
ing wallto another facade system such as a
have either thicker edges, to form an integral
formed in the bott om of t he panel,t extured
rainscreen set forward of the panel, where
'frarne' to the panels, or be completely flat,
finishesare formed within the mould, usually
thermal insulation is set on the outer face of
but the later will usually be thicker;and con-
by a synthetic rubber mat or polystyrene.
the precast panel. In addition t o setti ng pan-
sequently heavier. The 'framed' version has a
The shape of the panel is adjusted t o suit
els full height from floor to floor;loadbearing
visual language of framing which can be vis-
the ease of removing the mould when the
panels can also be set horizontally to form
ible from either the outside or the inside.
concrete has been poured in place, but most
structural beams between precast columns,
Due to their self weight, panels are usu-
typically around 1200mm high to provide
ally supported at their base at the floor slab
spandrel panels.This allows full length glaz-
and are restrained at the top of the panel
ing t o be used, set between the t op of the
with mechanical fixings. Panels are usually
panel and the botto m of the panel above,
a maximum of around 3600mm wide t o
MCH
156
panels can achieve sharp lines that do not have an obviously 'moulded'appearance.
---
-------
Plan I:25.Typical wall construction
Details I. Concrete floor deck 2. Precast concrete panel
3.Window 4.Vert ical joint (typically a baffle) between panels 5, Horizontal joint (typically a lap) between panels 6, Drywall/dry lining 7. Concrete floor deck 8, Steel dowel 9. Drywall/dry lining
(])
3-D view of wall assembly
(])
HousingViliaverde. Madrid, Spain,Architect:Chipperfield Archit ects
Vert ical section I:25.Typical wall construction
MCH
157
W a ls 02 Concrete 2: storey height panels
Housing Viliaverde, Madrid, Spain. Architect:Chipperfield Architects
3-D view of wall assembly
System details Joints between panels are similar for
either an extruded synthetic rubber gasket
grinding wheel lubricated with wat er,that removes up to 2mm of the material with
both loadbearing and cladding panel types,
or a wet-applied sealant.Loadbearing pan-
with a common use of either 'open' or
els are sealed with a cement-based grout.
a single pass of the grinder to a honed or
'closed' joints. Open joints have an outer
Closed joints are mostly used in loadbearing
fully polished finish.This exposes the colour
open joint that is narrow but admits small
panel construction where panels are joined
of the aggregate but the surface does not
amounts of rainwater, which is drained down
together with mechanical fixings. Panel fixings
shine naturally varnishes can be applied to
an inner chamber and released backto the
are positioned near the corners, with slotted
achieve this stone-like appearance,Acid
outside at the base of the panel through
fixings used in order to allow for both ther-
etched finishes are well suited to precast
a stepped horizontal joint.This internally
mal movement between the panel and sup-
panels since the amount of acid applied can
drained and pressure equalised system is
porting structure and for adjustment during
be more carefully controlled in the factory
similar in concept to that used in unitised
construction.The cleats are typically fixed to
than can be achieved on site.The outer face
curtain walling. In closed joints the outer
a small channel fixing cast into the concrete.
of the panel is treated wit h hydrochloric
face is sealed with a wet applied silicone or
Panels are lifted into place on site by crane,
acid to reveal the concrete texture beneath,
polysulphide sealant in a similar wayto the
using hooks that are screwed into threaded
which is then rinsed off, havingthe effect of
sealing of joints between bolt fixed glazed
tubes set into the concrete typically on top
revealing the concrete texture immediately
panels. Jointwidths both vert ically and hori-
or on the backface of the panel.The hooks
beneath.Acid etching attacks limestone
zontally for both open and closed joints vary
are unscrewed when the panel is in place,
aggregat es, and sometimes more quickly
from IO-25mm increasing with panel width
and the holes plugged.
than it doesthe cement, while silica-based
up to a maximum of around 6000mm.The
The most common finishes in precast
aggregate remain s.The surface texture
inner chamberbetween panels in vertical
panels are acid etching, polishing, sand blast-
achieved varies wit h the fine aggregate used,
open joints is closed wit h a synthetic rub-
ing andtooling.The lasttwo techniques are
being more granulat ed in the case of silica
ber strip which provides a primary seal.The
discussed in the next section on small pre-
and less coloured in the case of limestone.
interior face of both vert ical and horizontal
cast panels but can be applied equally here.
joints is closed with an air seal formed with
Polished finishes are formed by an abrasive
MCH
158
Details I. Concrete floor deck 2. Precast concrete panel
3.Wi ndow 4.Vertical joint (typically a baffle) between panels 5. Horizontal joint (typically a lap) between panels 6. Drywall/dry lining 7. Concrete floor deck 8. Steel dowel 9. Conrete coping 10.Thermal Insulation I I. Roof construction
Vertical section I:25.Parapet detail
CD I
Vertical sectionI:25 showingtypical details
3-D view of wall assembly
Corner details
MCH
159
ails 02 Concrete 2: sma ll precast pane ls
---..,.
Panel installation
:I![l:- -
One Coleman Street. London, UK. Architect: David Walker Architects
C
Plan and elevation I :25. Glass reinforced concrete (GRC) panels with open joints
System design Small precast concrete panels have a
frame, and at every fioor level in buildings
concrete in place of a fully encased concrete
greater sense of visual variety possible with
with more than one storey. Panels at ground
panel. but this makes it more difficultto stack
a reduced unit size than large panels. While
fioor level are set on a beam edge to a con-
panels andto maintain the economy of the
storey height panels suit larger scale projects,
crete fioor slab or structural beam. Panels
system. Self-supporting stacked panels fabri-
smaller self-supporting and interlocking pan-
are stacked with continuous vert ical joints
cated in thicknesses of 75- 1OOmm can also
els can be stacked together in the manner of
and are restrained by columns. The need to
form the outer skin of a complete cavity wall
composite metal panels. Panels have an inner
restrain panels on their vertical joints results
construction of 200-300mmthickness.The
core of thermal insulation with a finished
in interlocking panels being long in order
inner wall can vary widely in its construction
concrete face on each visible side of the
to optimisethe distance between struc-
from concrete block to light gauge metal
panel. Alternatively; individually supported
tural columns, avoiding intermediary posts
stud wall with an outer wat erproof facing.
rainscreen panels usethe visual language of
that would be required to provide lateral
The cavity between concrete panelsand
stone or metal cassette facades to a back-
restraint. In terms of weight. the long panels
backing wall is 50-75mm,vent ilat ed at the
ing wall in a different material. Small precast
compensate by being low in height in order
top and bottom of the wall.
rainscreen panels are fixed to a backing wall
to ensure their weight can be lifted by a site
either directly with individual fixing brackets
crane,typically with a lifting capacity of 4
formed with narrower joints than those
or onto an aluminium or stainless steel car-
to 6 tonnes. Since the stacked. interlocking
possible in full heightpanels, together with
rier frame, with open joints that follow the
panels have concrete on all sides, both hori-
the possibility of a non-rectilineararrange-
rainscreen principle.
zontal joints and vertical joints usually have
ment of joints. Fixing brackets are similar
a limited thermal bridge which can leadto
to tho se used for stone cladding, but are
porting wallssupported at their base.These
pattern staining as a result of different rates
usually biggerto support the heavier panels.
panels are shaped so as to ensurethey
of thermal transmittance in the material. in
W hile stone panel sizes are typically around
Panels can also be made as selfsup-
Small precast rainscreen panels can be
interlock to provide a stable form of con-
addition to the increased risk of condensa-
1500mmx750mm or 1500mmxIOOOmm,
struction. Panels can be stacked to a single
tion occurring on the internal face.The
depending on stonetype.precast rainscreen
storey height of around 10metres, with
thermal bridge can be avoided by the use
panels can typically reach 1500mmx-
lateral restraint provided by the structural
of metal connections between two skins of
3000mm. Panels are support ed on stainless
MCH
160
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Section I:25.Typical precast concrete wall construction. Left: Panels with drained joint. Right: Panels with sealed joint
Details I. Backing wall 2. Precast concrete panel 3.Closed cell thermal insulat ion 4.Vertical joint open or closed type 5. Horizontal joint open or closed type 6. Internal finish 7.W indow frame 8. Concrete floor deck 9. Precast concrete coping
10. Steel angle I I. Rubber-based baffle I2.W aterproof membrane
3-D view of wall assembly wit h angled precast concrete panels
MC H
161
Walls 02 Concrete 2: small precast panels
----
Panel casting detail
Details I. Backing wall 2. Precast concrete panel
3. Closedcellthermal insulation 4.Vert ical joint open or closed type 5. Horizontal joint open or closed type 6. Internal finish 7.W indow frame 8. Concrete floor deck 9. Precast concrete coping 10, Waterproof membrane
3-Dview of wall assembly with profiled, precast concrete tiles
steel brackets which are fixed either to pri-
the base of the panel provides an integral cill
beneath and forms a damp proof course
mary structure or to a carrier frame that is in
profile to the opening.The concrete facing
(OPC) which is positioned so that it extends
turn fixed to primary structure.Slotted holes
to all sides of the panel provides weather-
at least ISOmm above external ground level,
in the bracket provide adjustment vertically;
tight edges on the jambs and at the head
depending on climate conditions.The ope is
horizontallyand laterally. In common with
of the opening.Windows are set in a posi-
positioned so that the lowest row of panels
stone cladding, individually supported con-
tion which suits the position of the thermal
at ground level appears to sit on the ground
crete panels are supported on short lengths
insulation in the precast panel, typically in the
with its bottom edge either level, or slightly
of stainless steel angle at each fioor level in
middle,but windows are positioned to pro-
above the adjacent ground level or pave-
order to avoidthe possibility of progressive
vide continuity wit h the thermal insulation.
ment.This avoids the need for a ISO-200mm
collapse of cladding panels in the event of a
The closing of parapets is provided by
waterproofed plinth at the base of the wall.
single panel failing or slipping from its posi-
a metal fiashing that covers the top of the
tion. Fixings are designed so that they can
panel and the vertical face of the parapet
small cladding panels. Panels are sandblasted
support the full load of the panels immedi-
wall that may be set behind the panels
with iron filings rather than sand particles,
ately above it in the event of fixings to panels
to close off the roofThe coping is sloped
with the blasting slightly erodingthe face
above failing either partially or completely.
towardsthe roof to ensure that rainwater is
of the concrete, either backto the surface
drained onto it and not directed down the
or more deeplyto the coarse aggregate
facade. A precast copingcan also be used
beneath, resulting in a matt finish.Tooled
instead of metal, but an additional mem-
concrete is a method of texturing concrete
System details Interfaces for individually supported
Sandblasting andtooling are common on
panels are similar to those for stone cladding.
brane is set under both metal or concrete
with chisels or picks to makes grooves or
An advantage of small precast panels isthat
copings to ensure a fully watertight seal.
continuous textures.The textures usually
interfaces of stacked panels with openings,
The base of walls is detailed in a similar way
stop short of corners of wallsto give a crisp
parapets and cills are relatively straightfor-
to other forms of loadbearing masonryA
edge.
ward.Windows are fitted into openings
continuous damp proof membrane (OPM)
relatively easily, since the stepped profile at
extends up from the outside of the structure
MCH
162
StAlbans Pavillion, StAlbans, UK. Architect:MUFArchitects
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3-D view of wall assembly for GRC panels wit h open joints
Section I:IO.Junction at window jamb and at parapet
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Section I:IO. Panel soffit and window junct ions of GRC panels wit h open joints
MCH
163
als 02 Masonry loadbearing wal ls
Bluecoat Art Gallery. Liverpool, UK Architect BIQ Architects
Plan I:I O.W indow jamb connection in loadbearing brick wall
Vertical section I:I O. W indow opening in loadbearing brick wall
System design Loadbearing masonry wallsare used
render to provide the weatherproof skin.An
avoid cracking in masonry walls. Movement
mainly in small scale construction, but in
alternative solution is to set thermal insula-
joints in walls where cement-based mortars
recent years there has been a revival in their
tion within the wall,creating a loadbearing
are used are set typically at 6.0-8.0 metres
use for larger scale buildings asan alternative
diaphragm wall where the brick or block
depending on the required strength and size
t o the language of cavity wall construction.
can be seen on both sides of the wall, and
of wall. In lime mortars the strength of mor-
W alls are most commonly made from brick
also allows the internal face of the wall t o
tars is varied by altering the proportion of
or concrete block. In continental Europe,
be used for night t ime cooling within the
cement and lime which are usedto bind the
ter racotta blocks are more common, but
building.Two skins of brick,typically 2 1Smm
mortar t ogether.Increasing the proportion
are usually rendered on their external face,
to 3 ISmm thick,are set apart, joined by fin
of cement will increase its strength, while
both to enhance their appearance and for its
walls set perpendicular to the main walls.
increasing that of lime increases it s flexibility.
t raditional role as a weathert ight outer layer.
Concrete block wallsare made from skins
with mortar mixes having different propor-
Concrete blocks are similarly protected by
200mm to 300mm thick.The position of
tions of strength and flexibility. In addition,
render. O nly brickwork is fully exposed. rely-
the insulation within the walls, or on t he
the comparatively low wat er permeability
ing on the depth of wall to avoid the ingress
int ernal faceof the wall, allows a straightfor-
of lime gives it greater resistance t o rain
of rainwater.
ward cont inuity with the thermal insulation
penetration than mortar mixes with a high
provided by windows within openings.An
proportion of cement. Lime has the effect of
In brick construction,it is assumed that a 31Smm thick wall ( I Y2 bricks) is the
essential benefit of using loadbearing mason-
making mortars increasingly light in colour
minimum depth sufficient to resist rainwater
ry walls is their ability to avoid movement
with its increased proportion in the mix.
penetration in temperate climates.This is
joints through the useof lime mortar.This
However,mortar colour can be modified by
dependent upon brick density and manu-
traditional mat erial has lower strength than
adding pigments to the mix.W here stone is
facturing dimensions.W ith brick,thermal
mortars used in contemporary cavity wall
used on the outer face of the loadbearing
insulation is set on the inside face to allow
construction but has greater flexibility. allow-
wall,typically facing a brick wall behind,the
the material to be visible on the outside. but
ing it to move more freely without cracking.
mort ar has crushed stone added in place of
with concrete block,the insulation can be
This reduces, or can even avoid the need for,
sand in order t o give mortar its texture and
set on the outside with an external layer of
movement joints which are introduced t o
some of the texture of the stone itself
MCH
164
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Section I: I 0 Floor connection in brick loadbearing w all
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Details I. Loadbearing brick wall 2.Timber framed window
3. Internal plaster finish or dry lining/drywall 4.Thermal insulation
5. Precast concrete lintel
6. Precast concrete cill 7. Concrete loadbearing blocks 8. Damp proof course (DPC) 9. Sto ne facing blocks
10. Floor slab I I. Floor construction
12. Hollow bricks I 3. Roof construction
14. Stone lintel/anch 15. Stone cill
16. Parapet 17. Loadbearing concrete block wall I 8. External finish
3-D view of loadbearing brick wall system
MCH
165
ails 02 Masonry loadbearing wa lls
Plan I:IO.W indow jambs in brick loadbearing wall with stone facing blocks
Section I: IO. Window jambs in brick loadbearingwall with stone facing blocks
3-D section through loadbearing wall with stone facing blocks
System details
face of the wall from the underside of the
often with a more rudimentary brick arch
projectingcill. Where stone is used to form
behind it, concealed by the window frame. In
masonry walls is the need for the structural
cills, the material must be sufficiently impervi-
parapets, the coping piece has a damp proof
requirements of walls to take precedence in
ous or alternatively have sufficient slopeto
course (DPC) set beneath it to avoid rainwa-
the ways openings are formed, particularly
ensure that water runs off quickly. Where
ter being absorbed into the wall beneath.The
where the wall supports both itself and
softer stones are used such as sandstones
DPC is continuous with the wat erproof layer
other elements such as floors and roof. For
and limestones, the material must be suf-
used for the roof immediately behind the
example, the useof flat arches to window
ficiently dense and durable to avoid staining
parapet. In common wit h copings in other
An essential aspect of loadbearing
openings that form the equivalent of lintels
occurring due to water absorption. Cillsare
facade systems,the top is sloped inwards to
to support the wall above result in the struc-
usually made as single pieces to avoid joints
drain water towards the roof rather than
tural requirements beingthe dominating
beingformed which are less imperviousthan
down the facade where it would cause stain-
criterion in bringing componentstogether.
the cill material. A DPC is set under the cillto
ing.The coping usually projects beyond the
There are visual benefits, such as openings in
ensure that rainwater penetrating the outer
face of the wall on the roof side in order to
loadbearing masonrywalls having the ability
cill drains away any water that soaks through
throw wat er clear of the wall.
to reveal the thickness of the wall to give
the cill, particularlyat the joints.The heads
it a massive appearance. Cillsto openings
of openings in loadbearing masonry walls
are formed from either the same material if
are supported by lintels or arches which are
stone is used for the wall or, more commonly,
structural,takingon an appearance informed
precast concrete. Sometimes the timber or
by that primary requirement. In brick con-
metal cill that forms part of the window is
struction, a flat or curved arch is typically
used to form the cill where visual criteria
used to support the brickwork above. In
permit its use. Cills are sloped with a project-
concrete block construction, a reinforced
ing edge that throws the rainwater clearof
concrete lintel is used, which spans the com-
the wall beneath.A throating is also used to
plete width of the wall,while in stone a thin
avoid water running back to the external
arch is used on the outer face of the wall,
MCH
166
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Plans and sections I: IO. W indow opening in concrete block wall illustrat ing applicat ion of insulation to inter ior or exterior of wall system
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30 Finsbury Square. London. Architect: Eric Parry Architects
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Section I:IO. W indow opening in hollow brick wall
MC H
167
-----
ails 02 Masonry cavity walls: I . bri ck
Private residence, Dublin, Ireland Architect: Boyd Cody Architects
Woodward Place housing, New Islington, Manchester. Architect: FAT
Details I. Outerbrick wall (or 'leaf)
10. Inner precast concrete lintel
2. Inner blockwork wall (or 'leaf)
I I. Pressed steel lintel
3.Timber framed window
12. Outer precast concrete lintel or brick
4. Steel/Aluminium window 5.Timber cill
flat arch
6. Cavity closer 7.Internal plaster finish or dry lining/drywall 8.Thermal insulation
14. Roof Parapet 15. Stainless steel tie
9. Air cavity (sometimes omitted where insu-
lation fills cavity)
I 3. Floor Construction
16. Damp proofcourse (DPC) 17. Ground 18. Primary Structure
Isometric detail through window connection
System design Where loadbearingbrick walls usethe
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and vent ilated void behind, wit h an inner
and is restrained at the head by the fioor
overall wall thickness to stop the passage
skin that is wat erproofed wit h a high level of
slab or roof structure above.Taller buildings
of rainwater frorn outside to inside, cavity
thermal insulation.The cavity is vented top
have the inner skin built directly onto fioor
walls use two skins of rnasonry separated
and bottom to ensurethe free passage of air
slabs in the same way, but the outer skin is
by a venti lat ed air gap, where only the outer
through the cavityThis allowsthe cavity to
supported at each fioor level on a series of
skin is saturated wit h water. The inner skin is
remain dryas well asassisting in dr ying out
continuous stainless steel angles, fixed backto
usually formed in concrete block or timber
the outer skin of brick,which can become
the fioor slab.A damp proof course (DPC)
studwork, wit h thermal insulation usually
fully saturated in a rainstorm.The cavity is
is set on top of the steel angle to drain the
set on the external face of the inner skin.
bridged only by openings for windows and
cavity.W eep holes (vertical slots) are formed
Earlierexamples of cavity walls were built
doors, but typically this is done wit h proprie-
in the vertical joints immediately above the steel angle in order to allow wat er in the
by tying inner and outer skins together wit h
tar y cavity closers, which are insulated strips
fioor slabs to form diaphragm walls, so that
that create a thermal break between inner
cavity to drain t o the outside. In addition to
both inner and outer skins performed a
and outer skins.
being restrained at fioor slabs, the outer skin
structural function. Their use was reduced
The outer brick skin is usually only one
is also t ied at intermediary points backto
wit h concern over the thermal bridge cre-
brick thick,typically of IOOrnrn widt h, wit h
the inner skin wit h stainless steel ties.These
ated by linkingthe two skins of brick,wit h its
both skins being supported at ground level,
are set typically at 450rnrn horizontal centres
attendant issues of heat transfer across the
at intermediary floor levels and at the roof,
and 900mm vertical centres.vertical move-
wall and condensation risk. Current practice
depending on the height of the building.
ment joints are provided at around 7500mm
uses the outer skin as claddingto a drained
The inner skin is built off each fioor slab
centres, or are avoided altogether in the
MCH
168
3-D view of assembly showing cavity brick wall fixed to concrete frame
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Plan and vertical section I:IO.Typical connection or restraint to primary structure
MCH
169
W alls 02 Masonr y cavity walls: I . br ick
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Section I :IO.Junction at ground floor level
3-D view of double brick skinned cavity wall system
constr uction by keeping lengths of wall w it hin
int o a vertical OPC set into the jambs of the
t his limit.
opening w hich is in tu rn linked to a OPC set
At roof level there are many variat ions
under the cill to form a comp lete watertight
for eaves junctions , w it h th e t op of t he w all
System details
level as t he bottom of the cavity t ray.
seal to the o pening,wh ich in t urn is drained
maintaining a consistent principle of closing
to t he outside.A similar cavit y tra y pri nciple
t he cavit y at t he t op with a brick or block
inner and outer skins of cavit y w alls can be
is used to drain w ater at roof level and at
th at allow s t he load from t he roof structure
supported separat ely, wit h the outer skin
gro und level. In addit ion, a OPC is used at
to be support ed on the inner skin.A lt erna-
Unli ke loadbearing masonry wa lls,the
requ ired to suppor t only it self H owever,
ground level to avoid w at er being dr aw n up
t ively.t he roof str ucture may be supported
w hen an o pening is formed , t he cavity is
int o t he w all constructio n t o the inside face
on a column set int o the inner skin of t he
closed by a lint el to support t he inner and
of the w all w it hin th e building. OPCs are also
w all or on blockwo rk piers, also form ing part
out er skins at the top of the ope ning, and is
used beneath parapets and copings as w ell as
of the inner skin.The closing of the cavity w all
closed by a cill at the bottom of t he o pen-
at the junction of w all and pitched ro of
at t he t op allows fo r contin uity of th erma l
ing.T he jambs (sides) are closed by either
T he position of the OPC at grou nd
insulat ion fro m cavity w all to ro of structure
returning one of the two skins so t hat the y
floo r level is dependent upon th e differ-
w hile allow ing th e roo f construction t o be
meet, o r by setting an insulated cavit y closer,
ence in height between gro und floor level in
venti lat ed if required, and the top of t he
usually made as an aluminium ext rusion
the building and the adjacent exte rnal level.
cavity in t he w all to be vent ilat ed.A OPC is
filled wit h the rmal insulat ion. Because t he
The OPC in th e oute r skin is set at aro und
set o n t he under side of the brick or block
dow nw ard passage of w at er inside the cav-
ISOmm above ext ernal ground level.The
th at closes the cavity to ensure continuity of
it y is interrupte d by the lintel at t he head
OPC for t he internal skin is set at t he same
wat erproofing betwee n w all and roof Para-
of th e opening, a cavity tray formed fro m
level if th e step up from outside t o inside is
pets are closed at th e t op by a coping, eit her
bitu minou s felt is set above th e lintel to drain
aro und ISOmm. If th e difference bet ween
in masonry o r metal.A OPC is set beneat h
w ate r out of the cavity.Water is drained at
outside and inside levels is around 300mm
the coping to stop t he passage of w at er
th e bottom of th e tra y through w eep ho les
then the OPC is stepped up fro m outer skin
dow nwards from the t op of t he cavity.
in t he verti cal jo ints imme diately above th e
t o inner skin in th e same place but a separat e
OPC.The ends of t he OPC are t ucked dow n
OPC is added to th e inner skin at the same
MC H
170
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i 3-D view through typical timber window connections in brick cavity
wall
I Window assembly:Type D
MCH
171
ails 02: Masonry cavity walls: 2. stone and block
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Thermae Spa. Bath, UK.Architect: Grimshaw Architects
3-D view of junction at ground floor level of cavity wall.
Section I:IO. Typical window at cill and head in stone cavity walll
System design
ordinat ion of stone / block size and floor
are used, the junction between inner skin,
t o floor heights to allow for windows to be
typically concrete block or terracott a block,
set out in the previous t ext on brick cavity
suitably placed. For this reason, alternating
is straightforward with a gap between the
walls.The same principles can be applied for
bands of thick and thin stone are used in
tw o t o allow for structural movement in the
usewhen stone and concrete blockwork are
coursing.This allows horizont al joint linesto
frame. Stainless steel sliding anchors are used
used t o form an outer skin.
be provided at shelf angles, cavity trays and
either in the sides of the inner skin panel
The principles of cavity wall design are
DPCs at ground level without disturbing
where it meets the column, or at the head
skin approximately IOOmm thick.or as pan-
the stone pattern with additional horizontal
where it meets the floor slab.The outer skin
els around 40mm thick bonded to an outer
joints. Unlike open jointed stone cladding,
runs continuously in front of it.The situa-
brickwor k skin.Wh en used as a IOOmm
where the mortar is omitted,the mortar
tion is more complicat ed with a steel frame,
thick skin in order to be self-supporti ng, the
and joint profile have a big visual impact.
where the column needs to be protected
Stone can be used either as an outer
stone becomes expensive, so sandstones
Loadbearing cavity walls used to support
from corrosion from water vapour in the
and limestones are most commonly used.
tw o storey structures on their inner skins
cavity.Typically the column is painted to form
This method suits granites and denser
are very common in housing construction in
a protective coating and thermal insulation
limestones.An essential difference between
Europe and North America. Vertical move-
is set across the face of the steelwork to
the detailing of brick cavity walls and stone
ment joints are provided at around 7500mm
provide a continuity of thermal insulation.
/ block cavity walls is that there are fewer
centres, or else are avoided altogether in
Sometimes the outer skin is restrained with
joints in the material due t o their large size.
the construction by keeping lengths of wall
cavity t ies fixed to the face of the reinforced
Consequently t here are fewer opport unit ies
within these dimensions. Wh en cavity walls
concrete or steel column.This is particularly
to design a damp proof course (DPC) with
are used with large scale building frames in
useful when forming a movement joint in
floor slabs, for example, particularly where
either steel or concrete,the inner leaf is no
lengths of brickwork,or movement joints
shelf angles are used.The smaller unit size of
longer loadbearing and instead the complete
that form part of the building structure
brick makes it a very flexible material when
wall construction forms a cladding to the
which typically occur at columns in the build-
detailing; stone / block requires careful co-
frame.Whe n reinforced concrete frames
ing frame.The vertical movement joint is
MC H
172
3-D views of wall assemblies
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faced cavity wall system
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I . Damp proof course (DPC)
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2. Outer block wall (or 'leaf )
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3. Inner block wall (or 'leaf)
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4.Timber framed window 5. Precast concrete cill
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6. Stone cill 7.Timber inner cill B. Cavity closer 9. Internal plaster finish or dry lining/ drywall 10.Thermal insulation in cavity
..
I I.Air cavity (sometimes omitted where insulation fills cavity) 12. Inner precast concrete lintel I 3.Outer precast concrete/stone lintel 14. Stainless steel tie 15. Roof Construction 16. Floor Construction 17.Timber framed inner skin IB. Steel frmaed inner skin 19. Ground 3-D view of. timber window frame in stone cavity wall
Section I: I O. Typical window at cill and head
MCH
173
W alls 02 Masonry cavity walls: 2. stone and block
---""'
NoLi Housing.Philadelphia.Architect: Erdy McHenry Architecture
Vert ical section I:IO. Typical window at cill and head in block cavity wall system
filled with two part polysulphide sealant that
stainless steel fixings and restraints are usu-
through the top and bolting it to the inner
also matches the colour of the mortar as
ally post-fixed to the concrete. In recent
skin beneath.The coping is cut to receive the
closely as possible and provides a seal that
years, outer masonry skins have been made
balustrade or handrail, unless the uprights
can accommodate the structural movement
as prefabricated panels on some projects
supportingthe handrail pass between the
within the cavity wall.
when fixed backto a reinforced concrete
joints.The adjacent area of flat roof or gutter
wall. Panels of stone, terracotta or even
usually has a waterproofing layer returning
brick are bonded together with mortar and
up the wall. regardless of the roof finish. The
This section discusses variat ions and
then held in a steel edge frame, which is
wat erproofing layer is set into horizontal
System details details additional to those set out in the pre-
fixed to the inner skin.The concrete inner
joints in outer masonry skin.A metal flash-
vious section on brick cavity walls and focus-
skin is wat erproofed with bituminous paint
ing is set into the same horizontal joint and
es on different materials for the inner skin.
andthermal insulation is set on the outside
is set over the top of the wat erproofing
face ofthe inner skin.The steel angle on the
to protect it from damage. Metal copings
the window is usually an integral part of that
bottom edge forms a closerto the window
are used increasingly on parapets in order
inner skin so that a complete enclosure is
below,while the steel on the top edge forms
to matchthe appearance of windows and
formed in timber with masonry used as an
a cill to the window above.The vert ical steel
doors, particularly where metal cills are
outer skin providing some lateral stability. The
angles are usually concealed wit hin the cavity
used.The same principles apply as for con-
outer masonry skin can be returned to form
to give a continuous masonry appearance.
crete copings, with a DPC set on top of the
a reveal up to around 125mm depending
The masonry is sometimes restrained within
masonry wall.Drips are formed on either
When a timber framed inner skin is used,
on the thickness of insulation in the cavity.
the panel by vertical stainless steel rods
side of the vertical face to ensure that wat er
Alternatively the timber window can be set
which are tensioned against the frame to
isthrown clearof the wall.For all parapets,
forward close to the line of the outer face
form lightly prestressed panels.Yertical joints
the wat erproofing layer is continued up the
with a timber cill projectingforward of the
between panels are sealed,typically with a
wall to become continuous with the DPC
wall.This gives the outer wall an appearance
polysulphide sealant.
in low parapets. For high parapetwalls, a
of a brick texture, giving a planarappearance to the material. With reinforced concrete inner skins,
MCH
174
For parapets the inner skin is thickened
stepped DPC is used to drain water back
up when used as a balustrade. A handrail
to the inner skin to ensure that wat er inside
on top of the copingis fixed by drilling
this part of the cavity wall is drawn away.
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Details I. Damp proof course (DPC) 2. Outer block wall (or 'leaf ) 3.Inner block wall (or 'leaf) 4.Timber framed window 5. Precast concrete cill 6. Stone cill 7.Timber inner cill 8. Cavity closer 9. Internal plaster finish or dry lining! drywall 10.Thermal insulation in cavity I I.Air cavit y (sometimes omitted where insulation fills cavity) 12. Inner precast concrete lintel 13.Outer precast concrete/stone lintel 14. Stainless steel tie 15. Roof construction I 6. Floor construction 17.Timber framed inner skin
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MCH
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3-D detail of stone panels on carrier system Details I.Stone panel 2. Backing wall,typically concrete block 3. Stainless steel fixings 4.Timber framed window
7. Internal plaster finish or dry lining/drywall 8.Thermal insulation
5. Stone cill
9.Stone coping 10. Floor construction I I. Roof construction
6.Timber inner cill
12. Extruded aluminium/steel sections
System design thickness for various panel sizes. but this is
fixings are sometimes used depending on the
back either directly to a backing wall or to a
only a general guide and calculation is usually
weight and strength of the panel.
Stone cladding panels are typically fixed
St one cladding can be used as a 'wrap'
metal carrier frame wit h a separat e backing
undertaken for specific facade applications.
wall behind.The useof stone for cladding
Since the material may not already be cut
to a structural frame as well as its more tra-
requires an emphasis in the design stage on
from the quarry at the time of its selection,
ditional use for cladding walls with punched
choosing not only the specific material, but
stone facades can involve longer procure-
openings.The mixture of large stone panels
also setting the range of colours and tex-
ment times than ot her facade systems.
with long narrow panels associat ed wit h
tures of the material.This requires an inves-
particularly on larger projects.The stones
reinforced concrete structural frames gives
tigation int o establishing the physical prop-
used are typically granites. sandstones. lime-
a visual drama not usually associated with
erties of the actual stone to be used if this
stones and slat es, and are once again being
stone cladding until recently. The arrangement
is not already known,to a structural-based
considered as a material that might be locally
of stone panels can imitate traditional pat-
design to establish or confirm maximum
sourced; a material laying in abundance
terns of jointing such as stretcher bond, but
panel dimensions and suitable fixing methods
beneath the region in which the building is
can also benefit from the mechanical fixing
for the proposed sizes of panel.The physi-
to be constructed.
of each stone panel by forming an arrange-
cal properties of the stone may be available from the quarry at an early stage,but some-
Stainless steel is used for stone fixings because of its resistance to corrosion com-
ment that is independent of the backing wall behind. mixing both stone sizes and differ-
times testing is done during the early pro-
bined wit h high strength and rigidity. Fix-
ent shapes in a single wall composition. The
curement stage to ensure that he material
ings have a three-way adjustment vertically,
development of water jet cuttingtechniques
meets the requirements of the building code.
horizontally and laterally in order to align
in addit ion to development of established
The thickness of stone required for a facade
the stone panels accurately. The type of fix-
stone cutting tools has led to a greater vari-
is usually established by structural calculation.
ing used varies with the thickness and stone
ety in the size and shape that remains within
Flexural strength. also called the modulus of
type used. Fixings are usually set at the top
the limits of economic construction.The
rupture, is usually the most significant struc-
and bottom of the panel,with the bottom
introduction oftriangul ar panels in rainscreen
tural consideration in establishing panel size.
fixings being loadbearing and the fixings at
configuration has encouragedthe use of
Codes of practice often set out minimum
the top of the panel being restraints. Side
stone cladding on folded facade surfacesto
MCH
176
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3-D view of stone panels on individual fixings
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MCH
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complementthe geometries used in glazed walls. Finishes for stone have also developed in recent years, with rubbed, honed, polished and flamed finishes for different stonetypes.
System details Joints between stone cladding panels are either of open rainscreen type or are closed with mortar or sealant. Closed joints sealed with mortar or sealant are used where the cladding is supported at each floor level on stainless steel angles with jointed stones. With open jointed stones, each panel is individually supported in a rainscreen construction, where rainwater passing through the joints is drained away down either the back of the stones or down the face of the backing wall, 3-D view of stone panels supported on individual fixings
MCH
178
which is typically insulated.The choice of joint type is partly a visual decision and partly one
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3-D detail of stone panels on carrier system
that ensures adequat e vent ilat ion to the cav-
which can vary along its length by up to
ment joint width is usually around 20mm,
ity between the stone andthe backing wall,
2mm,depending on stone panel size and the
formed as an open joint.Vertical movement
allowing stones to dry properly Closedjoints
cutting machine used.Joint widths of 4mm
joints in the facade, located to correspond
allow the stone cladding to perform in a simi-
are common, but this can riseto around
to movement joints in the building structure,
lar wayto a cavity wall,with venti lation pro-
12mm when required for visual reasons.
are set immediately forward of these move-
vided at the top and bottom to dry the void
Movement joints are set both horizon-
ment joints where they reach the facade.The
behind the stones.Joints in sandstones and
tally and vertically to accommodate move-
distance between joints is typically at around
limestones are usually filled with cement/sand
ments in the building structure. Horizontal
6 metres in a continuous run of stone clad-
mortar or cement/sand/lime mortar. Granites
movement joints are used to deal mainly
ding wit h closedjoints.The joint width cor-
and slat estypically are proprietary sealants
with structural defiections in fioor slabs, and
responds to the expected movement in the
such as two-part polysulphide. Mortar used
are usually provided at fioor level, where
cladding, but where sealed joints are used,
for pointing is made frost resistant when
the stone cladding is support ed from either
the joint width is dependent on the amount
used in temperate climates, and of similar
short lengths of stainless steel angle, or a
of movement that the sealant is required to
strength to the joining mortar;with the struc-
continuous steel angle.The movement joint
accommodate.
tural mortar behind.The maximumwidth
is set immediately below the stainless steel
of mortar filled joints is around 12mm, but
angle, where vertical defiection will occur.
sealant filled joints can exceed this, subject to
Hor izontal movement joints can be set at
visual requirements.Joint widths are partly a
intervals of tw o storeys if a carrier frame is
function of the cutting toler ance of the stone,
used that will span the full height.The moveMCH
179
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System design Terracotta rainscreens are a recent
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I Vertical section I:I O. Terracott a rainscreen fixed to loadbearingconcrete wall
MCH
180
extruded as twin wall sections to provide
development over the past 15 years. and
long spanning panels.The range of glazed
can be seen as a development of brick cav-
finishes has developed considerably in recent
ity walls to a fully ventilat ed version in full
yearsto give a very wide range of t extures
rainscreen configuratio n. Over that time the
and colour mixes derived from contempo-
sizes of terracotta panels have increased
rary potte ry. Terracotta is made from natural
and fixing systems have developed,and have
clay that is first extruded.then cut to the
also been adapted for use as solar shading
required length of panel.then fired in a kiln.
louvres to glazed walls, particularly where
The use of extrusion dies allows the manu-
terracotta is also used as an adjacent wall
facture of t erracott a panels t o be flexible
cladding material.Terracotta louvrestypi-
from project to project.As with aluminium
cally comprise hollow sections reinforced
framed curtain walling,the die creates differ-
internally with aluminium sections to form
ent heights and depths of block while main-
louvered screensthat can match with adja-
taininga hollow interior t o keep the material
cent areas of terracotta cladding.Terracott a
relatively light and easy to handle, allowing
rainscreen panels are fixed either on rails,
long panel lengths to be formed.
into aluminium or stainless steel panels. or onto individual brackets like masonry clad-
System details
ding with concealed fixings.Vertically-set or
Terracotta panels have two extruded
horizontally-set rails are used to suit a range
edges and two cut edges, resulting in panels
of joint arrangements t hat imitate traditional
being arranged on a facade so as to avoid
masonry bonds. or alternatively can be fixed
a cut edge being visible at a corner. This
in a stack bonded arrangementRecently
arises because the surface finish and colour
developed systems have interlocking panels
of the end face will not match that of the
to provide visually crispjoints, and panels
front face.The ends of panels are usually
Det ails I. Backing wall,typically concrete 2.Thermal insulation 3.Terracott a rainscreen 4. Extruded aluminium carrier frame 5. Support clip, typically aluminium 6.Aluminium window surround 7. Metal framed window 8. Internal plasterfinish or dry lining/ drywall 9.Vapour membrane
Construction sequence of terracotta rainscreen cladding system
I0. Roof construction I I. Metal coping 12. Coping support 13. Stone paving
concealed with aluminium tri ms, sometimes at the corners but typically around window openings. Alternatively, special corner shapes can be formed by hand to match the standard extruded tiles, made by a pressing method,usual ly with a maximum length of 150mm on one leg and 300mm on the other. Large corner pieces are made by hand
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by joiningtwo sections together, but these currently produce less reliable results that can lacka straight and crisp edge. In addition, manufacturers often provide extruded cill sections for parapet s and window sections to suit wall constructions of 300mm to 500mm wide. Fired ter racotta is either left in its natural colour or is glazed. A glazed finish can give the material a refiective finish which provides better protection from surface staining. However, water absorption of regular terracotta panels is between 3%and 6%, with a densit y of around 2000kg/m3, making the use of glazes not essential for excluding rainwater but important more for visual reasons. Panels are fixed to support rails which are
MCH
181
W alls 02 Masonry rainscree ns Details I . Backing wall. typically concrete 2.Thermal insulat ion 3.Terracotta shingle 4. Ext ruded aluminium carrier frame 5. Support rail. typically aluminium 6. Rigid insulat ion 7. Glazing suppo rt 8. Met al wind ow casing 9. Metal framed w indow 10. Inte rnal plaster finish or dry lining/drywall I I .Vapour membrane
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I 3-D view of t erraco tta shingles hung on horizo ntal ra ils with proje cti ng w ind ow
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set either verticallyor horizontally, made
around ISOOmm long x 600mm wide x
come with the development of this facade
from aluminium for their abilityto be formed
40mm thick,requiring a more substantial alu-
system.Thinner terracotta panels of 30mm
precisely as extrusions for ease of fixing.
minium support section behind the panels.
thickness are used, in sizes with a maximum
Vertical rails are well suited to 'stack bonded'
The aluminium extrusions, set at the ends
length of around 800mm and corresponding
terracotta, where joints form a rectilinear
of each panel, sometimes project forward of
maximum height of 300mm.These thin-
grid of continuous vertical and horizontal
the terracotta as structural fins to provide
ner panels have maximum corner panels
joints. Horizontal rails are suited to staggered
the rigidity to the support framing without
of ISOmm on one leg and 300mm on the
bonds of panels that imitate the stretcher
requiringgreaterdepth in the cavity zone
other leg.The minimum sizes that can be
bond used in traditional wall construction
behindthe terracotta.Where used, the pro-
accommodated with the vert ical rail system
where vertical joints are not continuous. At
jecting fins give the facade a characteristic
are terracotta panels around 200mm long
least twice as many vertical rails are needed
appearance of vert ical bays of panels, where
x 200mm high, with a thickness of 30mm
as those for a stack bond arrangement. Since
only vertical backing supports are used,
to 40mm.Windows and doors are set into
horizontal joints are continuous, horizontal
divided by the visible edge of the aluminium
terracotta rainscreen cladding by fixing them
rails are used to fix courses of terracotta.
support. Corner pieces can be made in sizes
to, and sealing them against,the backing wall.
Jointwidths vary from 2mm to around
of 2S0mm x 300mm high, which often do
Aluminiumtrims used at corners and edges
IOmm, depending on the size of panel and
not correspond with the maximum length
of the panels can also be used to close the
type of fixing system chosen.
that can be manufactured for the planks,
gap between terracotta and window, with
but this constraintwill no doubt be over-
the trim on the bottom edge of window
The largest panels are planks up to
MCH
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openings useid to provide a cill. W indows and doors are positioned to form a continu-
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ity of weather proofing, and are typically set back from the face of the terracotta panels, with the t rim providing a crisp edge from a
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from either folded aluminium or rolled steel channels.The flat, planar nature of terracotta has led to the increased omission of reveals
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around window openings by pushing the window frame forward to align wit h the face of the terracotta panels, with insulated panels closing the gap between the window
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and the backing wall.Where terracotta is introduced as the material to form a reveal, corners are mitred with open joint s if special corner panels are not used.
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Vertical section I:20.Terracott a shingles fixed to concrete load bearing wall
MCH
183
Det ails I .Translucent Polycarbon ate cladding panel. insulated 2.Thermally broken extruded aluminium framing
3.W indo w inserted int o framing 4. Insulated comer panel 5. Ad jacent wall
3-D detail of composite cladding panel corner assebly
3-D view of window assembly within composite panel
System design The use of plastics is based on both
However;like aluminium it deflects consider-
way t o glass) with a secondary support ing
proprietary systems and tho se developed by
ably under high loads and requires stiffening,
structure behind, or alternatively by set -
manufacturers for specific projects. Plastics
but is more rigidthan other plastics. GRP is
ting thermally broken aluminium extrusions
are resinous, polymer-based materials, used
not combustible and can reach one hour fire
within the depth of the panels.That allows
in facade systems asthe primary material in
resistance in some cladding applications. GRP
them to be fixed together in the manner of
both sealed cladding panels and rainscreen
panels are formed by laying glass fibre cloth
composit e metal panels. Panels are also stiff-
panels.As sealed cladding panels their use
into a mould and coating it with resin and
ened internally wit h aluminium I-sections or
has been enhanced by the successful use of
catalyst, or alternatively spraying a mixture of
T-sections where large scale panels are used.
proprietary systems which combine lightness
glass fibre and resin into a mould.The face of
The arrangement of the framing can provide
in weight with high levels of thermal insula-
the mould is coated with a releasing agent
differing amounts of translucency across a
tion with panels of visuallyelegant appear-
to allow the GRP to be removed when it
panel, where some of the framing is either
ance. Concerns about the long term weath-
has set hard.
partl y visible, or completely concealed.
ering aspects of plastics,with their t endency
GRP panels are characterised by their
In addition to proprietary panels, GRP
to det eriorate noticeably with time, have
lightness in weight combined with being
and polycarbonate (discussed in the next
been largely addressed by manufacturers.
manufactured by moulding,allowing t hem to
section) can be used to form larger scale
The materials used are principally glass rein-
be made in large panel sizes, up to 6000mm
panels which are made by fabricato rs for
forced polyester (GRP), polycarbonat e and
x ISOOmm. Panel thicknesses are usually
individual projects.Thesetypically comprise
UPVC.This section discusses the use of GRP
70-7Smm t o provide structural stability and
two sheets of either profiled GRP or poly-
in sealed cladding panels which is the most
high levels of t hermal insulation. In common
carbonate fixed eit her side of met al framing
common material used. GRP is a composite
wit h metal composite panels, GRP panels
spanning floor to floor;or full height with
material made from thermosetting polyester
have undergone much development in
some additio nal restraint, to suit individual
resins, which set hard and do not melt when
the use of adhesives t o avoid delamination
projects.The main issue from the visual point
re-heated,that are mixed with glass fibre
between the outer skins and the insulation
of view is the choice of thermal insulation,
mat.This composite mat erial has high tensile,
core. GRP cladding panels can be made
which can provide either translucency or
shear and compressive strength combined
either as separate panels glazed into an alu-
opacity.W here translucent sheet is used, the
with lightness and resistance to corrosion.
minium pressure plate system (in a similar
insulat ion itself can form the primary visual
MCH
184
Exploded view of polycarbonate composite panel construction
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Horizontal section I:IO. W all assembly showing typical details
MC H
185
Walls 02 Plastic I: plastic-based cladding
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3-D detail showing connection between composite panel and cavity wall Composite panel junction detail
Details I.Translucent polycarbonate cladding panel, insulated 2.Thenrnally broken extruded aluminium framing 3.Window inserted intoframing 4. Insulated corner panel 5.Adjacent wall expression of the facade panel rather than
around a window, Integrating the window
or;alternatively, framing for stickglazing
the plastics, Natural materials such as straw
frame into the extrusion that supports the
curtain walling. Some manufacturers provide
bales and wool have been used to this effect,
GRP panels avoids the risk of leaks associ-
extruded I-sections, similar to those used in
ated with single silicone-sealed butt joints
GRP cladding, to clip the twin wall sheets
when a separate window frame and panel
to provide a completely lightweight system.
frame are fixed together.The integrated
This is a very economic form of cladding
minium framing is set within the panel form-
window frame allows water to be drained
which can be screen printed to create visu-
System details When formed as translucentpanels, alu-
ing a visible grid resembling that of tradition-
from the frame, GRP panels can be glazed
allydramatictranslucent facades.As with
alJapanese Shoji screens.These internal ribs
into large structural openings, from floor to
profiled polycarbonate sheet, other standard
are typically set out on a grid of between
ceiling for example, or can form a complete
components are not usually manufactured,
around 300mmx300mm to 300mmx600mm
glazed wall, restrained by a secondary steel
and folded aluminium sections are used for
centres.The void between the two skins
frame.When glazed into an opening, the
drips and parapet copings instead of polycar-
of the panel can be filled with translucent
edge T-section aluminium profiles are sealed
bonate sections, which are expensive to pro-
insulation quilt to increase thermal insulation,
against the adjacent concrete floor slab with
duce as new profiles. Although plastic-based
while still allowing a diffused light to pass
silicone,at both top and bottom.When
panels are usually made as panels fabricated
through the panel. Lighttransmission with-
fixed to a secondary support frame, panels
in a factory and fixed together on site in an
out additional thermal insulation istypically around 15%, with a U-value of I.5W/m 2 OK,
are supported at each floor level on metal
extruded aluminium glazing system, they can
brackets in either aluminium, mild steel (if
also be formed on site by fixing plastic-based
similarto an argon filled double glazed unit,
internal) or stainless steel (if exposed to the
sheeton either side of metal framing sup-
and a shading factor of 20%, which provides
weather).Cills and copings are formed with
ports.The cladding may be formed into pan-
a high level of shading for a glass-based wall.
the methods described in the section on
els or asa continuous wall structure.The use
Windows can be glazed into the panels, giv-
metal composite panels.
ingthe possibility of a rich mix of windows,
Where twin wall polycarbonate is used
of translucent insulation as an infill material that is not fully bonded to the supporting
in conjunction with other plastic-based
plastic skins provides considerable possibili-
need for complex framing.Window frames
panels, the material is fixed with either con-
ties for innovation.
can form part of the T-section extrusion
ventional aluminium framing for windows
doors andtranslucent panels without the
MCH
186
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Walls 02 Plastic 2: plastic rainscreens
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3-D section detail of polycarbonate rainscreen
@ Det ails I. IOmm plywood sheathing 2. Breather membrane
3.Vertical timber battens ~
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5. Profiled polycarbonate cladding (orientated vertically) 6.Composite timber joist 7.Thermal insulat ion
8. Internal dry lining 9.Timber framed window 10. Horizontal t imber battens I I. Screw fixing with plastic spacer 12.Aluminium window surround Vertical section I : 10. Polycarb onat e rainscreen cladding
MCH
188
I 3. Roof construction
3-Dcutaway details of polycarbonate rainscreen
System design is used in cladding for its translucency and
though the visual effects of dust settling
variety of types reflecting the overall range
transparency, achieving up t o around 90%
on the rear face of the rainscreen, and any
made in other materials: flat panels, cassette
light transmission.The material is extruded
periodic cleaning they may require, varies
panels, profiled sheet and shingled tiles. Plas-
or moulded (from polymer-formed gran-
between facade applications.
tic panels are used as either outer screens
ules) to form sheet materials that are flat
Plastic-based rainscreens are use in a
System details
to glazed walls, typically as solar shading,or
or profiled. Polycarbonate has a tendency
as rainscreen panels to an opaque wall.The
to yellow with age, which can be overcome
materials used are either polycarbonate or
with an acrylic coating. It is also used for its
around 2000mm x 3000mm and 2000mm
glass reinforced polyester (GRP).The use
high strength and impact resistance,ductility
x 6000mm, in thicknesses from around
Single layer polycarbonate sheet sizes are
of GRP is discussed in the previous section.
and lightness in weight However;because
3mm to 8mm. Profiled sheets are produced
Acrylic and UPVC,while softer than both
the material is combustible, its use in facades
in lengths up to around 10 metres, around
these materials, are used for window frames
is limited. It is also less durable than glass,
1200mm wide,with thicknesses around
and special moulded elements. In addition,
scrat ching easily which makesthe surface
Imm.Whe n opaque colours are used, rather
composit es are used for cladding panels,
dull with t ime,and has highthermal expan-
than the translucent or clear types, hook-on
made from thermosetting polymer resins
sion, up to 20% more than glass. Opaque flat
fixings can be secured to the rear face of the
mixed with cellulose fibres to provide sheet
sheet is fixed as rainscreen cladding panels,
panel, secured t o vertically- or horizontally-
materials with high durability which fade
made in a wide range of colours, Sheets are
set rails without the fixings being visible. Pro-
little in sunlight.In common with rainscreens
fixed either at their corners with an alumini-
filed sheets are fixed with selftapping screws
in other materials, panels or sheets are
um clamp on both sides, or with visible point
sealed with a weathertight washer and
fixed wit h either visible point fixings, verti-
fixings. Generally, plastic panels can be used
lapped on all sides, in the manner of profiled
cal/horizontal rails with partially concealed
with the full range of rainscreen configura-
metal sheet.This technique creates a shadow
framing members, or partially interlocking
tions of other materials, including the lapped
where they lap, which can be masked by
panels where there is no view through the
construction of timber boards and shingles.
the support structure behind, or may even
joints. Polycarbonat e is a thermop lastic,that
Like sealed plastic panels, plastic rainscreen
contribute to the overall visual effect. Cill,
is to say it melts at high temperatures,which
panels have the benefit of translucency.
drip and coping profiles are made from
MC H
189
Walls 02 Plastic 2: plastic rainscreens
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Details I.Opaque polycarbonate cladding panel 2.Thermal insulation 3.Concrete loadbearing wall 4. Internal plaster finish or dry lining 5.Waterproof membrane 6. Extruded aluminium carrier frame 7.Thermal break
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anyof the typical materials used: extruded
ods as flat sheet with thicker sheets being
x 1800mm in thicknesses from around Smm
aluminium, extruded UPVC or GRP. Profiled
supported up to around 1800mm centres.
to 12mm. Corner panels and parapets are
sheetcan be curved to a minimum radius of
Panels can be curved by setting them into a
also manufactured in the same material. Plas-
around 4000mm for a sheet of 50mm thick-
pre-formed aluminium edge frame, when the
tic-composite flat panels can be fixed with
ness, making it possible to create complex
material can be curved to a minimum radius
visible fixings or concealed point fixings.
geometrieswith an economic translucent
of 1500mm for twin wall sheets and around
material. Profiled polycarbonate sheet is
4000mm for the thickest sheets.
also made in a translucent white colour to
Plastic-composite flat panels typically
Polycarbonate is generally a rnore expensive material than GRP, making GRP rnore suitable for lower cost applications.
provide a light transmission of around 45%
have a mixture of around 70% softwood
However, GRP has one advantage over all
and in grey colours with light transmission of
fibre and 30% resin, manufactured at high
the other plastic-based materials, which is its
around 35%. Multi-wall polycarbonate sheet
temperature and pressure to provide
abilityto be moulded easily and economi-
can also be used for rainscreens, where its
coloured panels of smooth and almost
cally for small scale applications.When used
main advantage is the abilityto provide large,
impervious surface. Although the finish
as rainscreen panels the material needs a
flat panels as well as its inherently high level
colour is formed by using pigmented res-
top gel coat to avoid its fibres being seen.
of thermal insulation.Thicknesses range from
ins as a top coat in the mould,the colour
The abilityto see the fibres through the
4mm to 32mm in sheet sizes from IOOOmm
extends allthe way through the material,
material make it very unsuitable for transpar-
x 6000mm to 2000mm x 7000mm.The
allowing cut edges to be visible. Plastic-
ent or translucent panels, but for moulded
material can be screen printed or coated to
composite panels have high UV resistance,
rainscreen panels it is possible to introduce
provide a wide variety of colours on a large
high colour stability, high fire resistance and
some 3-D modelling into the facade panels.
format sheet. As with flat sheet, the material
can be cut and drilled eaSily, allowing them
GRP can be bonded to honeycornb panels
can be coated to give UV protection on one
to be used as overlapping shingles.Their high
formed in the same material to produce
side or both sides to avoid yellowing.The
impact resistance makes them well suited to
large panels with high fire resistance.
sheet material is used in increasing numbers
conditions susceptible to damage.The mate-
of walls, from twin wall to five or six walls
rial is made in sheetsizes from 3600mm x
thick.Panels are fixed using the same meth-
1800mm, 3000mm x 1500mm and 2S00mm
MCH
190
3-D view of opaque polycarbo nat e panels fixed to concrete loadbearing wall
3-D fixing detail of opaque polycarbonate panel
MCH
191
W alls 02 Timb er I: timber frame
Framing
Sheathing Harmood Children's Centre,London, UK, Architect: Greenhill Jenner Architects
Boarding arrangements A. Feather edge boarding B.Tongue-and-groove boanding
C.Tongue-and-gnoove boanding with inserts D. Shiplap boanding
Cladding
Assembly sequence
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@
System design There are two enduring generic forms
exposure and location, but mostly these pan-
escape t o allow the timber wall t o release
of loadbearing timber frame that use small
els are clad with an additional material on
and absorb moisture with changes in the
section timbers to form framed loadbearing
the outside to provide weather resistance.
weather. O uter t imber cladding boards are
walls: the platform frame and the balloon
Another system, where plywood is bonded
then fixed on the outside of the breather
frame. Both the platform frame and the bal-
t o each side of a rigid insulation panel, called
membrane,Traditionally, timber cladding was
loon frame are based on softwoo d sawn
structural insulated panels, or 'SIP' panels,
used to st iffen the structural frame by fixing
t imber sections.The platform frame compris-
provides a solid panel where the insulation
the boarding directly to the frame, with a
es studs spanning from floor to floor,with
holds the structural plywood sheets in place,
breather membrane set between the frame
the timber floor structure being supported
allowing timber wall construction to be thin-
and the timber boards as a weatherproof
at each storey height set of timber frames.
ner and lighter.
layer. More recent ly, the timber cladding is
The balloon frame,which is now used to a
Timber frames comprise studs (vertical
fixed to battens set forward of the breather
much lesser extent, is enjoyinga revival in
sections) fixed to rails (horizontal members)
membrane, or waterproofing layer, to ensure
light gauge steel sections.This method has
which are clad wit h plywood sheathing to
that the timber is ventilat ed on both sides.
vertical framing members which are con-
provide lateral bracing,typically 12mm-
The inside face of the timber framed wall
tinuous, with the intermediary floors being
18mm thick,depending on panel size and
has a continuous vapour barrier set (in tem-
supported by t he wall running continuously
loads.Timber boards can also be used as
perate climates) on the warm-in-winter side
past it.A recent development has been in
sheathing, but this is an expensive solution.
of the wall.The inner face of the wall is then
'solid' construction rather than the framed
Framing members are typically formed from
finished with a dry lining,
type. Laminated structural timber has been
IOOxSOmm softwoo d sections at 400mm
developed to makewall panels as complete
vertical centres which are nailed together.
is made in panels up to approximately
proprietary systems where the material is
Voids between the framing members are
16000mm long,3000mm wide and to a
glued together t o make full t imber panels.
filled with thermal insulation.A breather
maximum thickness of around SOOmm, vary-
Solid laminat ed structural timber
Thermal insulation is added to one side of
membrane is then fixed to the face of the
ing between propriet ary systems.The main
these panels, with the possibility to expose
sheathing layer.This provides a waterproof
benefit of the system is that it provides an
eit her t he outside or inside, depending on
barrier which also allows the vapour to
alternative t o steel and concrete frames for
MCH
192
Vertical section I :20. Roof junction
Details I.Timber boards 2.Timber battens 3. Plywood sheathing 4.Timber studs S.Timber rail 6. Breather membrane 7. Engineered floor joist 8. Damp proof course 9.Vapou r barrier 10.Timber floor I I. Concrete ground slab 12. Internal plasterfinish or dry lining/drywall 13.Thermal insulation quilt set within timber frame 14.Timber framed window IS.Timber cill 16.Air gap 17. Roof buildup
/
I /
/
I /
I
/
Vertical section I:20 showing typical details
3-D cutaway section showingtypical wall construction
MC H
193
ails 02 Timber I : timber frame Details I.Timber boards
9.Vapour barrier
2.Timber battens
10.Timber floor
3.Plywood sheathing
I I. Concrete ground slab
4.Timber studs
12. Internal plaster finish or dry lining/drywall
5.Timber rail
13.Thermal insulation quilt
6. Breather membrane
14.Timber framed window
7. Engineered floor joist
15.Timber cill
8. Damp proof course
16.Air gap
3-D cutaway section showingtypical wall construction
Vertical section I:20. Flat roof connection
Plan detail I:5. Outward opening window
Plan detail I:5. Inward opening window
MCH
194
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r.
Examples of vert ical and horizontal cladding anrangements
Privateresidence, London, UK.Archit ect: Lynch Architects
largerscale projects.This panel system has
to provide support between pads.W here
brick wall.The void beneath the timber floor
recently been used for buildings up to eight
an expression of a concrete floor slab is
is ventilated wit h air bricks that encourage
storeys high, providing loadbearing walls in a
required, the edge of the slab is covered
cross ventilat ion.This avoids stagnant air in
single material which is light in weight. Struc-
wit h thermal insulation,wit h an additional
the void from damaging and eventually rot-
tural insulated panels, with integral insulation,
outer protection,typically a thin concrete
ting the timber floor.
are made in panels up to approximately
facing panel.The timber wall frame is usu-
Corners, both external and internal
6S00mm long, 1200mm wide and in thick-
ally set on a continuous timber section at
type,are formed typically with a timber
nesses up to around ISOmm, depending on
ground level, which is first fixed to the con-
bead set so that the timber boards on both
the manufacturer. Curved wall panels are
crete slab to provide a level surface to set
sides butt into it. If a breather membrane is
madeto shallow radius.They are used typi-
the timber in place.A damp proof course
used behind the cladding, then an additional
cally as a direct alternative to traditional tim-
(OPC) is set beneath the continuous tim-
waterproof flashing is added to the corner.
ber framed construction, and like laminated
ber base plate usually extending down the
This is formed in a durable polymer-based
timber panels, are set to become more
vertical face of the concrete slab where it
sheetor metal sheet. Alternatively, the
widely used in timber construction.
connects with the damp proof membrane
boards can be allowed to makea corner
(OPM) beneath the concrete slab or the
with a butt joint, and an additional L-shaped
System details
vertical face ofthe basement wall.The OPC
timber trim , formed from two separate
is also made continuous wit h the OPM set
timber sections, is added on the face of the
ber cladding is terminated at ground level
on top of the concrete slab.Where concrete
corner to protect the exposed end grain of
at a minimum of ISOmm above external
foundation pads are used,the timber beam
one of the sides forming the corner. Boards
ground level.The cladding is usually sup-
is set into stainless steel shoes fixed to the
can be joined with a mitred joint (45°)
ported at ground level on a concrete slab or
pads.Timber can also be supported on brick
without any cover strip but the timber used
edge beam that forms part of the concrete
walls set at a minimum of 150mm above
must be of the highest quality to avoid the
wall.Alternatively,the wall can span between
external ground level and be support ed on
joint opening up with moisture movement. A
concrete pads at 3000mm-5000mm centres,
a concrete strip foundation or ground beam.
waterproof layer or flashing is set behindthe
with timber beams at the base of the wall
An insulated raised floor is then set into this
mitred joint.
For all these timber wall types,the tim-
MCH
195
al s 02 Timber 2: clad ding panels
Exploded diadram show ing assembly of timber cladding panels
System design windows set into the panel behind.This can
inner chamberformed between two adja-
widely used in recent years as a method of
create a visually rich mix of timber panel
cent panels. Any rainwaterthat penetrates
cladding steel and concrete frame buildings
assemblies that usea single timber species.
the outer seal, which is also kept open in
with prefabricated, factory made panels that
However; the highermoisture movement
some designs, is drained down an inner
have a natural finish.They are also used in
associated with timber has the consequence
chamberwhere the water is discharged
twin wall facades, or 'double skin facades'
of requiringjunctionsbetween cladding
through the horizontal joint at the bottom
where an inner timber wall with window
panels to provide an allowance for both
of the panel. Where timber cladding is used
openings has an additional glazed screen
structural movements and moisture move-
in twin wall construction as an inner wall to
set approximately one metre in front of it
ments both between cladding panels as well
an outer glazed wall where the outer wall
to provide a thermal buffer to reducethe
aswithin the panel itself
provides a thermal buffer; the outer screen
Timber cladding panels have been more
effects of heat and cold at different times
Where timber cladding panels are set
provides protection by allowing the material
of the year; as well as allow the windows
forward of floor slabs in the manner of
to maintain its appearance without full expo-
to be opened in taller buildings. Where
glazed curtain walling, panels extend from
sureto outside conditions, other than the
timber cladding panels are fixed to a timber
floor to floor;either hungfrom a floor slab
effects of the sun which cause the timber to
frame, or structural laminated frame, the
or;more typically, supported on it at floor
change colour.
cladding panels can be set between timber
level.Vertical joints between cladding panels
When cladding panels are set onto
columns as well as in front of them to give
have a stepped joint to allow for deflections
floor slabs, and restrained at the slab above,
a combined timber frame and panel build-
in floor slabs between panels, following prin-
timber posts that may form part of the
ing using a single primary material system.
ciples of glazed curtain walling.This stepped
structure can also be set between panels
Thesecladding panels are typically faced in
joint is covered on the outside with timber
rather than inside the building, since there is
timber boards in rainscreen configuration.
boards, set forward of the face of panels
no significant thermal bridge from outside
A recent addition to the language of timber
on battens in rainscreen configuration.The
to inside, allowing the structural frame to be
rainscreens has been the use of thin slats to
construction of panels followsthe same
exposed on the outside. Cladding panels are
create a degree of translucency in timber
principle of timber cladding described in the
set into openings in laminated timber frames,
screens, particularlywhen set forward of
previous section. Horizontal joints have an
with panels supported at their base on the
MCH
196
Details I.Timber boards 2.Timber battens 3.Plywood sheathing 4.Timber panel frame 5.Timber louvre 6. Breather membrane 7.Timber framed window (fixed) 8.Vapour barrier 9. Profiled metal cover strip 10. Floor construction I I. Air gap 12. Internal plaster finish or dry lining/drywall 13.Thermal insulation quilt 14.Timber framed window (out-
Elevation of timber cladding panels showing relationship with structural frame
ward opening) IS.Timber cill
Framing
II
~
II
Sheathing •
III
jill
I
II
IIII
II
Cladding
3-D section of timber cladding panel
Assembly sequence
showing integrated window
MCH
197
ails 02 Timber 2: cladding panels
lil~1
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3-D view of connection between timber cladding panel and supporting frame
-
Vertical section I:I0 through timber cladding panelsshowingtypical details
beams set beneath. Floor decks in timber
rainscreen applications. W here less expen-
are then fixed to the side of the laminated
sive, less durabletimbers are used, higher
timber beams.Timber panels are fixed at
levels of both protection and maintenance
their base to the beam beneath, but have a
are required. Softwood boards are made
lateral restraint at the top to allow the slab
usually in 250mm widths, with trimmed
and panel above to deflect without damag-
boards with profiles routed into them usu-
ingthe panel below.A metal flashing at the
ally trimmed down to 150-200mm widths.
base of the panel drains water and throws it
All timbers vary in moisture content with
clear of the beam beneath in order to avoid
changes in temperature and air humidity,
staining of the timber beam.The outer tim-
this being one of the essential aspects to be
ber rainscreen cladding is set flushwith the
considered in timber detailing. Most timbers
outer face of the laminated timber frameto
used in cladding will have a moisture content
avoid any views into the waterproofing layer
from around 5% to 20% when in use. Similar
behind.
levels are found in timbers from timber sup-
System details
or'seasoned'.The most common types of
pliers, and are classified as 'dry','kiln dried'
Both softwoods and hardwoods are
MCH
198
jointing of boards is'ship lapping'where tim-
used for cladding panels, with durable hard-
ber boards are set horizontally and lapped
woods being more commonly used for
over one another wit h the upper board
3-D view of cladding panel assembly with built in opening window
3-D view of timber cladding panel consisting of fixed glazing and louvre screen lapped over the top of the board below to
ter; or wood stains and paint. Paints can be
protect it from rainwat er ingress. Ship lap-
oil-based or acrylic,while preservatives are
ping can be assisted by the use of'feathered'
clear and can be used asa finishthat does
or wedge-shaped boards to give the lapping
not appreciably change its appearance. It
a more elegant appearance.Tongue and
can also be used before staining or painting
groove boards are used to give a continuous
the timber. Preservatives help to prevent
flat appearance,while having the advant age
moisture absorpt ion as well as reduce fungal
of locking boards to gether into a continu-
growt h,enhancingthe life of the timber but
ous plate-li~ structure. Boards are typically
not preventingthe material changing colour
around 20mm thick, made as long as pos-
and fading to its characteristic silver grey
sible at around 3000mm- 3500mm,to avoid
appearance.An essential issue in the use
vertical joints which are a potential source of
of timber cladding panels and rainscreens
rainwater penetration except in rainscreen
is the coordinat ion of timber types and fin-
configuration.Timber cladding is finished
ishes used for windows,doors, visible panel
with the timber being left either as supplied,
framing and rainscreen cladding, in order to
wit h preservative applied or injected by the
give a controlled visual appearance that will
supplier, or alternatively is given coats of
weather consistently together.
preservative in clear,stained.or opaque finish
Carmarthen Place. Londo n, UK.
on site wit h preservatives t hat repel rainwa-
Arch itects in Residence
MCH
199
ROOFS Trends in roof design Metal roofs I Metal standing seam 2 Profiled metal sheet 3 Composite panels 4 Rainscreens 5 Metal louvres Glass roofs I Greenhouse glazing and clamped glazing 2 Silicone-sealed glazing and roofl ights 3 Bolt fi xed glazing 4 Bonded glass rooflights Concrete roofs I Concealed membrane 2 Exposed membrane 3 Planted roof Timber roofs I Flat roof: mastic asphalt coverings 2 Flat roof: bitumen-based sheet membranes 3 Pitched roof: tiles Plastic roofs I GRP rooflights 2 GRP panels and shells Fabric systems I ETFE cushions 2 Single membrane: cone-shaped roof 3 Single membrane: barrel-shaped roof
MCH
20 I
Roofs 03 T rend s in roof design
An overview of roof systems the visually refined and very water tight
required to be sufficiently rigid and resistant
to be either of traditional appearance, as
standing seams which are 'zipped' together
to impact damage from occasional access.
with tiled and slated pitched roofs, or else
by machine on site. Since the introduction
Composite sheets with a plastic core and
completely concealed asflat roofs, they are
of 'zip up' sheeting,the difference between
thin metal outer facings are popular in this
now increasingly considered to be a part of
profiled metal and standing seam systems has
regard since they achieve high levels of flat-
a completely visible envelope design which
reduced, with new hybrid systems having a
ness and are flexible enough to withstand
is as visually important as the extemal walls,
lining panel system which can be fixed with
foot traffic, usually when aluminium sections
both in their appearance and their techni-
metal sheets, some of which are being hung
are silicone-bonded on the underside of pan-
cal performance. In recent projects, walls
down from the roof level without scaffold-
els. Perforated and slotted metal sheets are
and roofs are taking on a single form, with
ing. This makes large roof spans, particularly
also being used as metal rainscreen panels,
the same construction methods, materials
at high level, such as in covered sports halls,
partly shaping the expression of the building
and detailing used on both walls and roof
much easier to construct since scaffolding is
envelope in forming a continuity between
The increased technical performance and
not required.
different parts of a roofscape, ranging from
W here roofs were once considered
long term reliability of roofing materials of
Composite roof panel systems have been
covering air extract terminals, rooflights and
alltypes has led to a much more ambitious
in development since the I980s, wit h panels
gutters to producinga (seamless) smoot h
design approach. However, an essential
that provide an intemal ceiling finish and
continuation of the facade below. These
difference between facades and roofs is
outer roof covering in single panels that are
rainscreen panels can also accommodate
that facades have rainwater running across
semi-interlocked, with either a lapped metal
complex geometries wit hout having to make
their surface, but roofs can be submerged
joint between panels or a metal capping
individual composite panels to achievethe
in wat er during rain. A roof has to be com-
that clips over a standing seam-type joint.
same visual effect. Although such panels are
pletely sealed in areaswhere wat er can
Composite panels are now being used as an
an additional roof covering rather than being
collect, such as parapetgutters, with the
insulated structural deckto a separate water-
formed entirely from metal, they can provide
assumption that rainwater will be expected
proof membrane set on top. W hile lack-
varying amount s of translucency andtrans-
to remain on the roof if the rainwater out-
ing visibility of metal faced panels, they are
parency in a single metal layer that can reveal
lets become blocked.
very adaptable and economic, with thermal
its depth both from inside the building and
insulation not only filling the voids between
from outside.
Metals
peaks and troughs of the metal sheeton its
The increased reliability of jointing together wit h the increased use of aluminium sheet, with it s increased flexibility,
A change over the past 10years which
underside but also providing some structural
has influenced all types of metal construc-
stability.
tion is the increased quality of the finishes.
Metal rainscreen panels are a recent
instead of steel sheet has led to more
addition to metal roofing systems. They
The quality of powder coating has improved enormously, with greater durability and
adventurous roof forms without affecting
do not usethe outer seal as a first line of
colour-fastness, so that it competes strongly
the waterproofing performance. By the
defence against rainwater penetration but
with the more expensive PVDF finishes. Con-
early I990s profiled metal roofs were using
rather as a protection to the membrane
sequently, the main constraint in the design
standing seam joints,which combined the
beneath against the effects of the sun as well
of metal roofs in any of these systems isthat
as foot traffic. Metal rainscreen panels are
metal sheet is produced in widths of around
long span capability of profiled sheet with MCH
202
1200mm or 1500mm, from which most
this method, a metal channel is set into the
fixings on its extemal face. While bolt fixed
metal panels in facades are made, but is usu-
edge of double glazed units, with the units
glazing can conceal the fixing bolt within the
ally available in long lengths where coil mate-
being set flush with one another along the
double glazed unit on one side, structural
rial is used, that is, where the metal is rolled
horizontal joints. The units are then secured
silicone glazing has no visible structure at all,
into a long coil in the factory. Thicker plate,
with metal 'toggles' held to the metal chan-
with supporting glazing bars being concealed
at 4mm thickness and above, is made in flat
nels within the depth of the joint, and fixed
within the width of the joint behind the
sheet form, at around I OOOmm x 2000mm
to an aluminium frame below to provide a
extemal seal. This has led to greater freedom
mechanical fixing. The flush horizontal joint
in the forms used for rooflights in this tech-
in size, with
larger sheets being more difficult
to obtain easily in large quantity. Working
between units is then sealed with silicone.
nique, where the position of the glazing bars,
with the width of the coil in forming joints,
The aluminium frame onto which the glass
and how they intersect, does not have to be
and allowing for the folding or tuming of the
is fixed has ventilated drainage channels to
considered in rooflight design. Bonded glaz-
material at the joints, is the main constraint,
take away any water that passes through
ing has encouraged the use of structural glass
but the material can be curved and folded
the outer silicone seal. With the develop-
beams, which suit well a structurally glazed
economically in a durable material.
ment of silicone bonding techniques, the
rooflight. Most bonded glass rooflights with a
double glazed unit can also be bonded to
gently sloping, but planar surface are derived
aluminium profiles which are mechanically
in part from examples of glass floor decks
fixed with screws to a supporting frame. The
and staircases used in buildings that have
have been in use for the past 25 years, the
joint between the glass units is then sealed
been developed over the past I 5 years. A
Glass Although drained and ventilated systems
issue of the water tightness of the horizontal
with silicone in the same way as the previous
new addition is to bond point fixings directly
joint, running perpendicular to the fall of the
example. An altemative approach has been
to the inside face of the glass, with brackets
roof, has been undergoing continual develop-
to introduce horizontal glazing bars with
and support systems used for regular bolt
ment. Glazing bars have been used to sup-
pressure plates that are shaped to allow as
fixed glazing.
port glass down the slope of the roof where
much water to drain down the roof as pos-
they do not impede the passage of rainwater.
sible, and accepts that the same water will be
Horizontal joints have been supported with
trapped behind the upper edge of the pres-
Developments in waterproofing mem-
stepped joints where water runs off the top
sure plate. Small amounts of water that find
branes for concrete roofs over the past 25
Concrete
of the upper glass down onto a lower glass.
their way through the outer seal are drained
years have focused on increasing the flex-
The glass is traditionally secured with clips
away within the system back to the outside.
ibility of the material used. Asphalt, a well
and is sealed with a proprietary sealant. This
Both the recessed fixing method with a sili-
established material for concrete decks, suf-
joint is difficult to seal reliably in order to
cone seal, and the modified pressure plate
fered traditionally from an inability to take up
achieve water tightness for higher wind pres-
'toggle' system have been proved reliable in
movement from either the building structure
sures, and is difficult to adapt to a drained
their performance.
or from solar gain when exposed to the
and ventilated system. This issue has been
Bonded glass rooflights are a recent
effects of the sun. A solution to this problem
resolved over the past 20 years with the
development in glazed roofs, where dou-
has been the 'inverted' roof configuration,
development of silicone sealed glazing that
ble glazed units are bonded directly onto a
where thermal insulation is fixed above, rath-
was originally used in glazed curtain walls. In
lightweight metal frame that has no visible
er than below, the waterproof membrane
MCH
203
Roo s 03 T rends in roof design
in order to keep its temperature cool and
being used on substrat es such as folded steel
relatively constant. Pebbles or paving slabs
sheet decks and foam insulation-clad roof
slated and shingled roofs usetwo lines of
are set onto the insulation. In addition, the
decks where there is a strong modellingof
defence against rainwat er penetration. where
introduction of polymers into asphalt to pro-
the fonm of the roof structure seen either
the outer layer is the outer line of defence
vide great er flexibility has led to the material
from inside or from outside the building.
to, and protection for, a waterproof mem-
being easier to apply on site, particularly as
Membranes are required to accommodate
brane or breather membrane beneath.
not, until recently, playa part. Modem ti led,
t orch-on membrane sheet rather than in liq-
more structural movement and higher tem-
uid applied fonm. However, polymer materi-
peratures combined with an extemal wearing
recent development. This technique is a
als, mainly thenmoplastics and elastomers,
surface that can be walked upon without
hybrid of lappedtile roofing and standing
are becoming more economic. Polymer
reasonable risk of damage, for maintenance
seam facades, and can be used to fonm both
materials have t he advantage of increasingly
access.
wall and roof in a single system that is both
being able to be exposed to sunlight, which is leading to roofs being covered in a few of these materials asa self-finish, with some
The use of metal shingles has been a
economic and able to deal with a variety
Timber Timber-based roofs have developed over
of fixing angles. W hile shingles or t iles are hungfrom their top edge, metal shingles are
buildings takingthe membrane down the
the past 20 years to improve their thenmal
folded over into a seam on t heir sides and
facades to fonm a complete building enve-
insulat ion perfonmance. So called 'cold' roofs,
lower edge, or edges, if the shingles are not
lope. Where a smoot h or level insulated
with the insulation set at ceiling level with the
rectilinear, but are set at 45° t o the verti-
substrate can be fonmed, these waterproof-
roof void being ventilated, continue to be
cal, for example. The top edge or edges are
ing layers can be fixed in a similar way t o
used, but 'warm' roofs have undergone much
fixed with nails or screws with the shingle
fabric membranes, welded together in the
development in order to properly deal with
immediately above being lapped over the
factory to fonm a membranewith straight
the needs of ventilation to avoid condensa-
top of t he nailed fixing in the manner of tiling.
and crisply fonmed joints t hat can fonma vis-
tion occurring within the roof construction.
This fixing method securesthe shingles on all
ible self-finish to a roof, with an appearance
Some manufacturers prefer t o have no ven-
sideswhile retaining a visual lap, allowing the
similar to that of fabric 'tent' membranes.
tilation within the roof construction where
shingle to be fixed in any position, even in
This change from roof membranes which
it cannot be easily provided by using a high
a soffrt condition. The fixing method usually
are kept concealed, due to their poor visual
perfonmance vapour barrier on the inside
follows rainscreen principles by assuming that
aspect, t o ones that are now capable of
face of the wall construction immediately
rainwater will pass through the joints, which
being a visual part of the design.
behind the intemal finishes. Manufacturers
are drained in a ventilat ed cavity behind.
also provide increasingly better perfonm-
Metal shingles are economicto fabricate,
polymer-based membranes, or polymer
ance vents to ensurethat air can be drawn
since they can be cut easily from sheet metal,
modified asphalt sheet, are beginning to be
thro ughthe void between the roof tiles,
from aluminium, mild steel, copper or zinc.
used as materials in their own right rather
slates or shingles, and t he breather mem-
In addition, ti les can be fonmed t o a curved
than imitatingthe appearance of traditional
brane or roofing felt that is set above the
shape in a press to give a very textured
roof t iles or shingles. The more refined fix-
thenmal insulation. Most of the effort in ven-
facade with a three-dimensional quality that
ing t echniquesthat are being made available
tilating pit ched roofs of this type is in trying
has yet to be explored.
by manufacturers will assist in this change.
to retain the appearance of traditional roofs,
W aterproof membranes are increasingly
where ventilation ducts and boiler flues did
O n pitched roofs, visually exposed
MC H
204
Plastics
Translucent plastics are used mainly both to imitate the appearance of glass roofiights
Fabrics The use of woven textiles made from
approach is that it relies on a constant supply of air to hold the roof in place rather than by
as fiat sheet materials, and to form composite
polymers has been focused on its applica-
a supporting frame. This method has been
panels. This is gradually changing as plastics
tion to form tent-like roof forms. Tent-based
adapted as small 'cushions' or 'pillows' filled
are no longer seen as economic substitutes
structures stretch a single membrane sheet,
with air to provide an insulated fabric mem-
for other materials but as construction mate-
which is waterproofed on its extemal face,
brane roof. The most visually striking exam-
rials in their own right. Earlier examples of
over a supporting structure that may use a
ples use ETFE foil which is both very durable
plastic roofiights suffered from the effects of
mast to support the tent, and cables to hold
when compared to other polymer fabrics,
colour fading or of yellowing in transparent
the membrane in position, in the imitation
and also highly transparent. While this can
/ translucent roofiights. The materials and
of a traditional tent. This has led to devel-
be a disadvantage in roofiights where some
finishes used in bonding are superior to those
opments in the connection of membrane
amount of solar shading is usually required, it
used previously, ensuring that colour fading
to cable and restraint of cables to adjoin-
is ideal for many facades and is finding use in
is far less pronounced than it was. A greater
ing structure. Altematively, membranes are
complete building envelopes, where wall and
acceptance of plastics as durable and capable
stretched over more sculptured supporting
roof is formed from a mixture of transpar-
of being moulded economically to complex
frames, which are derived more from the
ent and translucent panels. These panels are
shape has prompted a revival in roof design.
established language of building construc-
infiated, fixed to a permanent air supply that
Some panels have been used as translucent
tion rather than from the masts and cables
periodically refreshes the cushions with more
rainscreen panels with lighting or graphic
of tent-based roofs. The design life of these
air to maintain the pressure required to give
displays set beneath the outer plastic skin.
roofs is gradually increasing as both a result
them structural stability. The use of fabric is
The essential difficulties for plastics remains
of observing earlier examples and develop-
set to grow, with air cushions that can be
in their perception as being less durable
ing them, as well as an improvement in the
used in conjunction with extemal solar shad-
than either glass or metal, for which polymer
performance of the protective coatings
ing or intemal screen walls in a variety of
materials are seen as economic substitutes.
applied. The introduction of double layer
twin roof or twin wall applications. Like sheet
This perception will change only when more
membrane roofs will no doubt change
plastic materials, ETFE cushions are becoming
complex geometries of extemal envelopes
their use from purely weather barrier to a
liberated from the design language of glass
are demonstrated in buildings which could
thermally insulated roof, making them more
rooflights, with more complex geometries to form curved roofs. Loadbearing air cushions,
not otherwise have the budget available for
attractive for roofs to intemal spacesthan
such work in other materials. Working with
shelters for extemal spaces. More translucent
which do not require any supporting struc-
plastics and composites is still undertaken
insulation materials reduce the amount of
ture, are in their early stages of development
in relatively small-scale workshops, where
light transmission lost through these roofs,
and application, and we are likely to see
mock-ups can be produced easily and eco-
with research being undertaken to form an
much of this development in roof structures
nomically, allowing an interaction between
economic and highly translucent thermal
and self-supporting envelope structures in
designer and fabricator that is more difficult
insulation material that would suit double
the coming years.
in larger scale factory-based methods where
layer membranes. An altemative method
repeatability of large numbers of identi-
of insulating membranes is to fill the gap in
cal components still dominates production
a double layer membrane roof with air to
methods.
form an inflatable roof. The concem with this
MCH
205
Roofs 03 Metal roofs I: metal standing seam Details I, Metal sheet 2, Standing seam joint 3. Breather membrane 4, Thenrnal insulation 5, Substrate, typically timber/ metal rafters wit h plywood facing 6. Vapour barrier 7. Drywall/dry lining if required 8. Outerstanding seam sheet 9. Inner lining sheet
10. Clips at centres I I. Folded metal gutter 12. Curved eaves sheet 13. Extemal wall 14. Structural frame 15. Outersheet fixing bracket 16. Rooflight 17. Metal flashing I8. Ridge piece
Uji-an Tea house, Tokyo, Japan Architect: Arata Isozaki and Associates
3-D section through metal profile roof on timber structure
System design Standing seam roofs are increasingly
These applications makethe use of prefab-
of the water draining down it. Rainwater
being used for industrial and commercial
rication both unnecessary and uneconomic,
is avoided being drawn through the joint
buildings where concealed fixings and low
due to the time saved by fomning junctions
by capillary action by one of two methods,
roof pitches are required for visual reasons.
and edges on site. The use of a single sheet
where the joint is either sealed or ventilated.
The main advantage of standing seam roofs
metal profile and angle support clips used
In a sealed joint the seam is pressed tight, as
over profiled metal roofs is that almost no
in prefabricated methods is typically too
in a traditional lead or copper roof either by
fixings pass through from outside to inside
infiexible for such conditions. This traditional
folding the metal over itselfto fomn a thin
the construction. This givesthe roof surface
method of fomning standing seam roofs has
seam, or by fomning the metal over a timber
a visually crisp appearance with very few
timber boards or plywood sheet used to
roll or section. In a vent ilated joint, a small
visible fixings, The standing seams allow the
fomn a continuous substrate, or support-
gap is left between the folded sheets to allow
technique to be used on very low pitch
ing surface. Standing seams are fomned by
air to pass through but not rainwater.
roofs, The traditional method of fomning
timber strips of rectilinearor curved sec-
a standing seam roof is to set the sheet
tion which are set at 450-600mm centres
the most common configuration isto fix the
onto a timber substrate, and to fold the
down the slope of the roof, corresponding
brackets supportingthe outer sheetto a set
long edges of the metal upwardsto fomn a
to the width of the sheet metal used. Sheet
of metal purlins. A metal liner sheet is set
standing seam joint. However, this method
metal is laid alongthe length of the roof
below the purlinsto support the themnal
For prefabricated standing seam roofs,
is increasingly giving way to prefabricated
from top to bottom , with the sides of the
insulation quilt, set between the purlins. A
systems where the sheet metal is folded to
sheet folded up and over the timber battens.
vapour barrier is set between the insulation
a specific profile either in a factory or on site
Successive strips of metal sheet are lapped
quilt and the liner tray on the wamn (in win-
with a rolling machine, The folded metal is
over the next to fomn a continuous sealed
ter) side of the themnal insulation. An alter-
then secured with a clip-based fixing system
surface. The standing seam joint is produced
native configuration is to have a full structural
rather than onto a continuous substrate.
by folding the metal together to create a
deck with insulation set on top and an outer
seal. Becausethe roof is fomned, effectively,
(upper) sheet supported on brackets set
is well suited to smaller-scale applications,
as a series of linked gutters, the standing
onto the structural deck. In hot, humid
or where complex geometries are used.
seam between each gutter is above the level
countries an additional vapour barrier is set
The site-based method of fixing sheet
MCH
206
Vertical section I:IO. Typical roof assembly without acoustic layer
Vertical section I:I0 Typical roof assembly without acoustic layer
3-D cutaway view of typical roof assembly
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Vertical section I: IO. Ridge with recessed flashing
Vertical section I:IO. Ridgewith flashing
CD 3-D view of sheet metal on timber roof The Core. Eden Project, UK. Architect: Grimshaw Architects
MCH
207
Roofs 03 Meta l roofs I: metal standing seam 3-D view of folded eaves and ridge junction
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Vertical section I:IO. Folded Eaves Walt Disney Concert Halll, LosAngeles, USA Architect: Frank Gehry
on top of the insulation where the risk of interstitial condensation is from the outside
brackets are usually made from extruded
as well as the inside.
aluminium in order to provide a profile that
For both site-based and prefabricated
is both thick enough to fonnn a rigid con-
construction methods, the roof pitch can
nection and sufficiently precise in section
go down to 1°, after taking into account
to retain a given standing seam profile in
any structural deflections that would further
place. Metal sheet is fonnned in long lengths
reducethis angle. Metal sheets can be made
of folded trays which are then fixed onto
up to 40 metres in length, but road trans-
the support brackets. Finally the standing
port is difficult, being considerably longer
seam joints are crimped to fonnn a seal, usu-
than a trailer length. For largerprojects,
allywith a 'zip up' tool that travels alongthe
long sheets are fonnned on site with a roIl-
joint and across the roof, sealing the joint as
ing machine that can fonnn the profile of the
it movesalong.
standing seam sheetto any length required, Vertical section I:IO. Monopitch ridge
or to purlinswith self-tapping screws. The
the profile being fonnned from metal coil.
Standing seam sheets can fonnn shallow curves by gently bending the metal on site, or altematively by curving the sheets in the
System details Support brackets are usually T-shaped and are fixed either to the structural deck
MCH
208
factory, to give a smooth appearance. Small radius curves are fonnned by crimpingthe sheet in the factory, where the material is
~/ 3-D view of metal roof show ing eaves wit h curved gutter
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Vert ical sect ion I: IO. Eaves w ith curved gutter
mechanically fonrned with small local folds.
as bull nose profiles, the metal panels are
Sharp folded comers are made by welding
usually designed to be drained and vent ilated
tw o sheets t ogether along the fold line.
to the exterior, and the line of wat erproofing
Ridges are fonrned by a variety of methods, the visually sharpest being a ridge line
continues up the extemal wall to the underside of the standing seam roof.
fonrned as a standing seam joint with the
Section I : I0 Parapet gutter at abutment
seams meeting the ridge being tenrninated to avoid the need for visually bulky filler pieces which could be seen from below. Valleys are fonrned by lapping the ends of the standing seam roof into a folded metal tray fonrni ng a continuous gutt er. Eaves are fonrned in a similar way, with a gutter set at the edge of the roof. Increasingly, gutters are being int egrated int o roof fonrns in order to avoid a weak visual line fonrned by a gutter which is not continuous with the smooth lines of the roof. W hen additional closer pieces are used, such
3-D view of metal roof at abutm ent
MCH
209
Roo s 03 Metal roo fs 2: profiled metal sheet
Atelier and House, Bwa-Cho, Japan. Architect: Shuhei Endo
System design The main advantage of profiled metal sheetover other metal roof types is the
on the geometry of the roof. Profiled metal sheet provides a continu-
some breathing thro ughthe ribs of the profiled sheet. This helps to keepthe insula-
ability of the material to span economically
ous weatherproof skin with the ability to
tion completely dry. Becausethe inner lining
up to around 3.5 metres between primary
be curved in one direction, where the sup-
sheet presents a hard surface under the roof,
structural supports. This self-supporting abil-
porting structure beneath requires only a
perforated sheets are usedto improve sound
ity of the material, combined with its weath-
few structural members to be curved, and
absorption. Sound is allowed t o be absorbed
er resistant, painted coating applied during
most framing can be straight.The material is
partly by the insulation quilt. This helps to
manufacture, makes it able to be used as
lapped on all four sides like metal standing
reduce reverberation, particularly in noisy
both a substrat e material for a finish in a dif-
seam roofs. The laps are made long enough
intemal environments. A vapour barrier is set
ferent material set onto it, or as a single layer
to avoid capillary action through the joint.
between the thermal insulation and the thin
structural and weat herproof material. W hile
This simple jointing system provides large
layer of acoustic insulation beneath. Profiled
standing seam roofing, with its high project-
areas of reliable, weathertight roofing that
metal sheet roofs have the ability to conceal
ing folds, is suit ed to long, straight, or gently
can be installed quickly. In common with
the supporting structure within the depth of
curving spans, profiled metal sheet can both
standing seam roofing, profiled metal roofs
the roof construction. This gives a smooth
span between supports and form complex
can be used as a roof covering in eit her
finished appearance to the inside faceof the
geometries. It is this flexibility of being both
sealed or ventilat ed construction. Vent ilation
roof. An outer metal sheet is supported on
structural deck and wat erproofing layer that
is used mainly where a timber supporting
metal roof purlins, and an inner lining tray,
has an advantage where the interior finish is
structure is used, where the timber is venti-
which supports the thermal insulation, is
designedto be in a different material, such as
latedto avoid rot in the material from moist
fixed to their underside. Sheets are fixed with
dry lining or decorative boarding. In recent
air in the void that would otherwise be
self tapping screws which, in addition to fixing
years roof pitches have greatly reduced to
trapped wit hin the construction.
the sheets t o the supporting structure, are
In sealed roofs, the thermal insulation
also required to be weathertight. A vapour
visual reasons. Most profiled sheet is laid to a
usually fillsthe voids in between the inner
barrier is provided on the warm (in winter)
minimum pit ch of around 4°. Standing seam
and outer skins, but ventilators are often
side of the insulation, between the liner tray
provided at the ridge and eaves to allow
and the thermal insulation. Laps between
makethe roof as flat as possible, usually for
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roofs can go down to a 1 pitch, depending
MCH
210
,I Vertical section I: I O. Concealed gutter detail
Details I. Outer standing seam sheet 2. Inner lining sheet 3. Clips at centnes 4. Plywood substrate 5. Breathermembrane 6. Thenmal insulation 7, Folded metal gutt er 8. Curved eaves sheet 9. Extemal wall 10. Standing seam joint I I. Stnuctural frame 12. Outersheet fixing bracket 13. Rooflight 14 Metal flashing 15. Ridge piece 3-D section thro ugh roof constnuction using profiled metal sheet
Vert ical sectio n I: 1O. Typical profiled metal 3-D view of profiled metal roof construction
sheet roof construction
MCH
211
Roofs 03 Metal roofs 2: profiled metal sheet
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3-D section through typical valley and ridge construction
profiled sheets along their top and bott om
beneat h the profiled sheet. Closer strips are
is not possible in profiled sheet, and instead
edges are sealed wit h butyl sealant strip. Two
used to seal the gaps in the profiled sheet
a folded ridge piece is fixed to the upper sur-
strips are normally used, one at the end of
where it meets the ridge cover strip set on
face of the profiled sheet. The gaps between
the extemal lap and the other at the top end
top of the profiled sheet.
the ridges and troughs of the profiled sheet
of the intemal lap.The outer seal provides
Parapets are formed by creating a gut-
are filled with a proprietary metal filler piece,
protection against capillary action of rain-
ter at the base of the profiled sheet,t hen
usually forming part of the manufacturer's
water being drawn up into the lap between
continuing the line of the gutter up to a
system. Ventilated roofs do not require this
sheets, while the other provides a vapour
parapet coping with laps over t he top. The
filler piece, with the resulting gap between
barrier that avoids moisture, generated inside
gutter is formed from a single folded sheet
the folded ridge sheetand the profiled sheet
the building, from condensing in the joint Self
to avoid the possibility of leaks, and is lapped
being usually sufficient to provide ventilation
t apping screws that hold the sheets in place
under the vertical sheet that forms the seal
into the construction.
clamp the two sealed surfaces together.
between gutter and coping. Parapets in pro-
Sheet s are normally lapped ISOmm over one
filed metal sheet are often used where the
another, while laps between sheets on their
extemal wall is formed in a different mate-
side edges are made with a single lap of pro-
rial, so that the parapet forms a visual break
file, with a single seal of butyl tape set at the
between them. However, many profiled
centre of the lap.
met al roofs are used in conjunction with walls in the same material usinga concealed
System details Ridges at the junction of a double pitched roof use a folded metal strip to form
gutter that allows wall and roof to be continuous. Ridges and valleys are formed using the
a continuous ridge sheet. These sheets can
same methods discussed in the previous
be folded on a straight line or formed t o a
section on standing seam roofs. But where
curved line.The void beneath is filled with
standing seams can be cut down to form a
thermal insulation in addition to that used
flat ridge without a projecting ridge piece, this
MCH
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Vertical section I:20 Ridge with flashing
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5. Breather membrane 7. Folded metal gutter 8. Curved eaves sheet 9. Extemal wall 10. Standing seam joint I I. Structural frame 12. Outersheet fixing bracket 13. Rooflight 14 Metal flashing 15. Ridge piece
Vertical section I:20. Prefabricated valley gutter
MCH
213
Roofs 03 Metal roofs 3: Composite panels
-
3-D view of verge with parapet upstand
System design There are two types of composite panel
bonded to a foam-based insulation that fills
combine the separate components of
used for roofs: double sided panels and sin-
all the voids in the profiled sheet, providing
profiled metal sheet have two joint types:
gle sided panels. The first is a development
a smooth, flat upper surface. The depth of
a double seam wit h a cap on top in the
of profiled metal sheet, where outer sheet,
the panel is determined by both structural
manner of standing seam roofing, or a single
thermal insulation and inner sheet are com-
requirements and the U-value required, var-
projecting lap of metal profile that forms a
bined into a single panel. These are used in
ying the thickness of the thermal insulation.
lapped connection with the adjacent panel.
pitched roofs and have an appearance very
The upper face of the panel is waterproofed
W it h the first method, panels have raised
similarto that of profiled metal roofs. Their
with an independent membrane, typically an
edges on their long sides running down the
main advantage over profiled metal roofs
elastomeric type that requires no upstands
slope. The raised edges are butted together
is the speed of erection on site, but they
or special joints between sheets. Panels
and sealed wit h butyl tape. A metal capping
are usually a little more expensive than an
are usually set butted up to one another,
is fixed over this joint to provide a weather-
equivalent profiled metal sheet roof Single
with the gap between panels filled with
tight seal which sheds wat er onto the panels
sided panels consist of profiled metal sheet
foam-based thermal insulation. A separating
either side of the joint, givingthis method
bonded to one side only of a layer of foam
layer is usually set between the waterproof
a distinct appearance of wider joints. The
type thermal insulation. The insulation is laid
membrane andt he insulated panel to allow
second method has an uninsulated rib of the
face up to receive a separate waterproofing
movement to occur freely in both the mem-
outer sheet projecting from the panel on
layer, typically a single layer membrane. The
brane andthe composite panel substrate.
one long side which laps over the adjacent
membrane isthen typically finished in rain-
The membrane is often protected with a
panel. This gives a continuous ribbed appear-
screen panels or smooth pebbles, depending
lightweight covering of smoot h pebbles
ance to the roof that is visually no different
on the geometry and required appearance
that can be walked upon for maintenance
on its outside faceto profiled metal roof
of the roof. This second panel type can be
access without puncturing the surface. Metal
cladding. Both methods have lapped joints
used on nominally flat roofs.
rainscreen panels are also used to protect
on their short (horizontal)edges, where an
the membrane from the effects of direct
uninsulated edge projects down to form a
Single sided composite panels have a single sheet of profiled metal on the lower loadbearing face of the panel which is
MCH
214
sunlight. Double sided composite panels which
lappedjoint very similar to that used in profiled metal roofs. These horizontal joints are
(3) _ - - - . - . .....- - - ' . - . . ....- - - ' - ' - - - - ' - ' - - - - ' - ' - - - . . " . - . . ...- - - ' r " " ' ' - - - - - r " "
Vertical section I : I0 th rough composti te panel showing panel to panel junction
3-D view of vert ical section through parapet edge and folde d metal gutter betw een panels
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Details I , Met al rainscreen panel
CD
2, Single layer membrane 3, Composite Panel 4. Folded metal coping 5. Purlin or structural beam 6. Secondary Purlin 7. Folded metal gutt er
8. Folded metal drip 9. Metal fascia panel
3-D view of panel connection
10. Extemal Wa ll I I . Outer sheet fixing bracket 12. Panel I
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3-D view of composite panel suppo rti ng rainscreen panel
MCH
215
Roo s 03 Metal roofs 3: Com posite pane ls
Sainsbury Centre for Visual Arts, Norwich, UK Architect: Foster Associates.
also sealed with butyl tape to avoid capillary
The flashing is profiled to matchthat of the
either by folding it outwards and sealing it
action from rainwater outside, andto pre-
panels onto which it sits. The gaps are then
or by folding the t op edge inwards, up the
vent the passage of water vapour into the
closed with a profiled filler piece as used in
underside of the panel. Unlike eaves gut-
joint from inside the building.
profiled metal roof construction. The ridge
ters, parapet gutters are thermally insulated,
flashing has visible fixings which are difficult
forming part of the extemal envelope. The
System details
to conceal, so that precise positioning is
gutter is usually prefabricated to form part
essential t o the overall visual appearance
of the overall composite panel system. The
Ridges and folds of single sided panels are formed in the same way as the panel to
of the ridge. The gap between the panels
gutter shape, in cross section, is formed to
panel joints, filled typically with a foam insu-
is filled with thermal insulation on site, with
provide continuity in the t hermal insulation
lat ion applied by injection on sit e. The mem-
eit her mineral fibre quilt or, more frequent ly,
from roof panel through t o the adjacent
brane sheets are usually joined at the fold in
with the same foam-based insulation usedto
parapetwall.
the roof, and a strip of the same material is
manufacture the panels. Insulation is injected
The t ops of parapets are closed with a
bonded along the joint to provide a weath-
into the gapt o provide a U-value to match
pressed metal copingthat is folded down
ertight seal. At parapet gutters of single
that of the adjacent panels.
over the face of the extemal wall and the
sided panels, an upstand is formed in the
The inner face of the panels forming the
inside face of the parapet to provide a com-
same insulation material as that used in the
ridge is sealed with a folded metal sheet.
plete weathertight seal. The top of the cop-
composite panels, the upstand being bonded
typically fixed to adjacent roof purlins and
ing is usually inclined towards the inside face
t o the composite panel beneath. The outer
sealed against the inner face of the compos-
of the wall, into the gutter, to avoid dust
edge of the upstand is sealed and stiffened
ite panel to provide a continuous vapour
settl ing on horizontal surfaces from being
with a metal strip fixed to the underside of
barrier, This inner trim is made either flat or
washed down the face of the extemal wall
the composit e roof panel or the supporting
profiled t o suit the composite panels used.
during rain.
structure beneath. Ridges for double sided composite
Eaves are formed in a similar way to profiled metal panels, by lapping the edge
panels are formed by fixing a metal flash-
roof panel over a gutter. The gutter is closed
ing over the junction between the panels.
against the underside of the composite panel
MC H
216
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3-D views show inggutter detail within co mposit e panelarrangement, hidden by rainscreen abov e
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2 \7
Roofs 03 Metal roofs 4: rainscreens
3-D view of metal rainscreenroof assemb ly
System design The use of metal rainscreen panels is
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MCH
218
to protect w at erp ro ofing membranes on
relatively new in roof construction and has
non-visible flat roofs. th ey are obviously not
developed from using the panels in exter-
suit ed to sloping or curved ro ofs. Th e use
nal w alls, albeit in a different configuration.
of metal rainscreen panels is w ell suite d to
Firstly, most of the rain falling onto a metal
the se more comple x roof geometri es w hich
rainscreen roof is not usually drained away
fonm a visible part of the design. The se rain-
on th e outer layer of panels, unless th e roof
screen panels allow t radition al roof elements
has a relatively steep pitch or curved section.
w hich are usually visually dominant, such as
Rainwater is st ill expected to drain onto the
gutters, parapets and ridges. t o be accom-
w at erproofing layer beneath as if the panels
modated w it hin a smoot h, continuous outer
w ere not in place. The main function of the
skin. allowin g roofs to take on the visual
rainscreen panels on roofs is to protect the
characteristics of ext em al wa lls. contributing
memb rane from the effects of the sun (heat
to th e overa ll archit ectural effect.
and UV radiation). from the worst effects of Vert ical sect io n I : I0 through roof assembly
A lt ho ugh smoot h pebbles are also used
A lt ho ugh metal sheet is used for rain-
w indblown rain and as protection for main-
screens, metal and plastic composit es are
ten ance access. Rainscreen panels also pro-
becomin g increasingly popul ar. In such
vide a lightweight covering th at fonms part
materials a thin layer of plastic is faced w it h
of the visual language of the extemal w alls.
two thin sheets of aluminium w hich are
3-D view of metal rainscreenroof assembly
3-D view of metal rainscreen roof support system
3-D view of metal rainscreen roof assembly with optional capping to seam
Details I. Metal rainscreen panel 2. Single layer membrane
3. Closed cell thermal insulation 3-D view of metal rainscreen roof fixing channel
4. Structural deck 5. Purlin or structural beam
bonded to the plastic sheet core to provide
600mm wide if they do not have additional
longer size panels than tho se of sheet metal,
supporting framing beneath to stiffen them.
with the benefit of providing greater flatness.
Framed panels can reach the maximum sizes
8. Folded metal drip
They are less likely to experience localised
already mentioned. but care must be taken
9. Metal fascia panel
impacts from foot t raffic during mainte-
to avoid the pattem staining or denting that
nance work, wit h the 'oil canning' effect of
can reveal the frame behind during the lifecy-
depressed or dented panels resulting from
de of the roof
regular maintenance access usually being
6. Secondary purlin 7. Floded metal gutter
10. Extemal wall I I. Outer sheet fixing bracket
Rainscreen roof panels are typically
avoided by using these composite sheet
anranged either as panels laid in a flat grid, or
materials. However, the size of metal rain-
as lapped panels, where the bottom edge is
screen panels is restricted more by the panel
lapped over the top of the panel beneath.
width that can be walked upon for mainte-
Side joints remain open jointed and are set
nance access than by the sheet size available.
in the same plane in this configuration. Panels
The maximum size of metal sheet is usually
in a flat grid are set onto metal Z-sections.
in a width of 1200mm or ISOOmm metal
which are either bonded to the top surface
coil. Composite sheets are typically IOOOmm
of the wat erproof membraneto avoid any
to 1200mm wide, in lengths from 2400mm
risk of water penetration through mechanical
to 3000mm. depending upon the manufac-
fixings, or are set above the membrane on
turer. In practice, panels may only be around
support pads. These pads are usually covered
Bercy Shopping Centre, Paris, France. Architect: Renzo Piano Building Workshop
MCH
219
- - -Roofs 03- - - - - - - - - - ---. Metal roofs 4: rainscreens
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3-D view of meta l rainscreen roof draining from panel to panel
Sectio n I:25 t ypical section with rainscreen panels draining from panel t o panel
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3-D detail of metal rainscreen support system
3-D detail of met al rainscreen suppo rt system
MCH
220
f-
Vert ical section I : IO. Concealed parapet gutter w ith cantilevered edge
'ML..-_ --' @
3-D view of concealed parapet gutte r w ith cant ilevered edge
with a waterproofing membrane to reduce
on the roof in order to provide a continuity
there is no need to leave the gutter uncov-
the number of fixing penetrations through
of appearance. The waterproof membrane
ered, as is the case with other metal roof
this layer. The rainscreen panels are then
beneath is then sealed against the wall con-
systems. Water running down the membrane
screw fixed t o t he Z-section wit h brackets
struction or against the side of the sealed
is drained directly int o the gutter, and water
that avoid the screw fixings being seen at
roof deck, which is closed off with a folded
undemeath the gutte r cover drains through
a distance where this is a visual require-
metal strip, in the case of profiled metal
slots or perforations.
ment. Concealed fixings are more difficult
sheet or composite metal panels being used.
t o accommodate, though such systems are
The depth of t he roof construction is
An advantage of rainscreen panels is their ability to form complex geometries from fiat
likely to appear over the next t en years as
t hen finished wit h another rainscreen panel,
panel components. Since the panels are not
demand for this roof system increases.
set vertically, which is fixed in front of the
required to be waterproofed, they do not
parapet. Unlike parapets in profiled metal or
require any joints between panels that would
composite panels, the vertical fascia panel
become difficult and expensive for roofs with
can extend up to the top of the wall in order
complex geometries. Flat panels can be fixed
parapets is that the gutter and upstand
to conceal the coping fiashing. In other types
down at their comers on a curved roof to
can be made without either element being
of metal roofing, the coping extends over the
create a set of gently curved panels that are
visible, allowing parapets to function as
top of the wall, resulting in a thin visual edge
tumed in either one or two directions. Panels
concealed gutters while providing a visual
t o the top of the wall. This coping line can be
are increasingly beingtwisted in two direc-
continuity between wall and roof. Conse-
concealed from view in rainscreen roof panel
tions in order to creategenuinely curved
quently, eaves, monopit ch ridges and verges
construction. The extemal wall beneath is
roof finishes. Altematively, panels can be set
can have a similar outward appearance of an
typically sealed up to the underside of the
fiat but with each panel at different anglest o
unintenrupted panel layout extending from
roof deck.
create a facetted roof section.
System details An advantage of rainscreen panels for
roof down to the extemal wall. Parapets are formed only by a gutter that also provides
The parapet gutter can be covered with a perforat ed or slotted metal cover in the
the necessary upstand height for the para-
same material and finish as the adjacent rain-
pet itself. A coping is then formed by using
screen panels. Since rainwater runs off each
the same rainscreen panels as elsewhere
panel at its edges onto the membrane below,
MCH
22 1
Roo s 03 Metal roo fs 5: metal lou vres
3-D view of louvred metal canopy and support
CD
3-D sect io n th rough louvred canopy edge and support
System design Where end caps are screwed to the ends,
pin connections. Two flat plates are welded
used ascanopies to provide solar shading
the aluminium profile has screw ports that
to the endsof the tubes, and a single plate
while still allowing daylight to pass through
fonm part of the extrusion, into which the
fonming a cleat is fixed to the underside of
the canopy. Louvre blades are set typically
screws are fixed. Aluminium extrusions can
the flat frame and the base support below
at 45° to the vertical in order to block the
be made in lengths up to around 6000mm,
the roof. The fork ends of the tubular sup-
passage of direct sunlight but allow the light
and are supported at centres to suit their
ports and the support cleats to which it con-
to be reflected off its surfaces down to the
structural depth. An elliptical section will
nectsare fixed together with face-mounted
space beneath the canopy. Louvre sections
span typically 1500mm for a 75mm to
or countersunk bolts to fonm a visually crisp
are created from folded strips of aluminium
IOOmm deep section while a 250mm deep
connection. The tubes have tapered ends
or mild steel sheet, but these have limited
section will span 2500mm, depending upon
shown which istypical of this type of steel
Arrangements of metal louvres are
stiffness and stability, requiring restraint
design wind speed and relative loads. When
construction. The aluminium louvre panels
along their length to hold their straightness
fixed at their ends, a fixed louvre assembly
are fixed to the supporting flat frame with
in length. Greater stiffness is provided by
can be made without visible fixings.
brackets that are welded to the sides of the bottom flange of the steel I-section. The alu-
extruded aluminium sections, where the elliptical section is most commonly used, mainly for its abilityto reflect daylight in a
System details The supporting structureto the example
minium louvre panel is supported on these brackets, with a nylon spacer between them
way that reveals its three-dimensional fonm,
shown comprises a mild steel frame fabri-
to allow for thenmal movement. The louvre
enhancing its appearance. Sections are
cated from box sections, supported by tube
panel is fixed to the cleat bracketwith a
either a half ellipse or a full ellipse. Flatlou-
sections that spring from points below the
countersunk bolt.
vre arrangements provide much less visual
roof The box sections are shown bolted
vibrancy when viewed from below. Extruded
together to fonm a flat frame structure, into
ing louvre assembly shown is made from
aluminium sections require end caps, usually
which are set louvre panels, prefabricated
either mild steel or aluminium sections.
for visual reasons, and these are either fixed
and finished in a factory, then fixed to the
Aluminium sections are usually prefenred for
with countersunk screws into the wall ofthe
supporting mild steel frame on site. The
their durability but mild steel is often used
section, or are welded and ground smooth.
steel tubes are fixed to the flat frame with
for its greater rigidity. Mild steel isgalvanised,
MCH
222
The supporting structureto the mov-
3-D detail of louvred canopy edge and support
Details I. Extruded aluminium louvre blade 2. Mild steel box section
3. Mild steel tube 4. Structural pin connection 5. Mild steel I-section 6. Bolt fixed metal panel 7. Aluminium sheet 8. Mild steel or aluminium support frame 3-D detail of louvred canopy edge and support
3-D detail of louvred canopy 3-D detail of louvred canopy edge and support
Forth Road Bridge Toll Plaza Canopy, Edinburgh, UK. Architect: Reiach & Hall Architects 3-D detail of louvre support
MC H
22 3
Roors03 Metal roofs 5: metal lo uvres
3-D view s of electrically operated louvre panel in open and closed positions
Detail s I . Extruded aluminium louvre blade 2. Standard rackanm 3. Drive shaft 4. Slat clip
MCH
224
...
3-D viewsof electrically operated louvre panel inopen and closedpositions
painted, or both, while aluminium, wit h it s
overall appearance of a single colour for the
also used for horizontal and inclined glazed
greater durability, can be natural, anodised
complete canopy, particularly when recessed
roofs, excluding up to 90% of solar heat
or cromated (similar to anodising) depend-
joints are used between panels. Flush joints
gain when set at a 45° angle. Louvre blades
ing on the individual application. Metal
in silicone tend to give the canopy surface an
are 75mm-1 OOmm in typical proprietary
panels of large size, made from 1200mm
homogenous appearance, giving it more the
systems but blades up to 300mm wide can
x 2400mm sheet, can result in a gentle oil-
appearance of concrete than of metal. This
be made as a single extrusion. Nylon sleeves
canning effect around their edges. This gives
can detract from the crisply fitted assembly
and washers are used at the connection of
panelstheir characteristic soft edge, but they
of panelswhich is characteristic of metal and
moving parts, rather than metal, to avoid
look smooth and consistent, and this is usu-
also one of the advantages of the material.
the need for regular lubrication. Louvres can
ally accept ed visually as part of their appear-
Louvres are typically a maximum of
be solid or perforat ed to different percent-
ance. If much thicker sheet is used, there
around 6000mm long for those 75mm to
ages of solid to void, from around 10% void
is a disadvantage in increased cost as well
100mm deep, requiring support at 1000mm
to a maximum of 50%, though the latter is
as a greater difficulty in working the sheet
to 1500mm. Sliding arms typically support up
difficult to fabricate. Louvres are fixed by
to form smooth shaped pressed panels.
to a 6000mm length of louvre blades, giving
steel pins int o a sliding aluminium section
Aluminium panels are typically either PVDF
an overall square shape (in plan) to each set
at each end of the profile. The louvres are
coated or polyester powder coated, while
of controlled louvres of 6000mm x 6000mm
also fixed at their centre in section. As t he
steel sheet is usually polyester powder coat -
size which are fixed int o the supporting
sliding aluminium rod moves, the aluminium
ed only. The useof anodised aluminium as a
I-section frame. A IOOmm deep I-section will
louvres move together. opening and closing
finish on sheet has increased in recent years
span typically IOOOmm - 1500mm between
together. The sliding rods are connected at
asa result of greater reliability of the finish,
supports depending on the design of the
each end of the louvres and are fixed to a
which until recently has suffered from une-
glazed roof below. The distance between
supporting frame of aluminium I-sections.
ven colour consistency. The silicone used to
the moveable louvre panels and the glazed
The single tube is powered by an electric
seal the joint s can be applied in a variety of
roof below is made sufficient t o allow for
motor, and as it tum s, the sliding arms move
monotone tints, ranging from white, to greys,
access for cleaning the glass below and the
through the arrangement of gears.
to black Some silver-grey colours match
louvre assembly itself
well with silver coloured panels t o give an
Electrically operated louvre canopies are
MCH
225
Roo fs 03 Glass roofs I : greenhouse glazi ng and capp ed systems
The Glasshouse, RHS Wisley, UK. Architect: Petervan der Toom Vrijthof
3-D view of typical eaves connection
Details I. Extruded aluminium glazing bar 2.Single glazed sheet 3. Rubber seal 4.Aluminium glazing clip 5. Extruded aluminium section 6. Aluminium clip on capping 7. Aluminium footing 8. Concrete base 9. Polycarbonate sheet IO. Double glazed unit
3-D detail of glazing support
Systems design Curtain walling principles used in extemal
duringrain. The condensation channel also
sections are separated from the glass by
walls have been adopted, over the last 20
serves as a drain for moisture inside the
extruded rubber-based seals which are held
years, as a reliable method of construct-
building that has condensed within the fram-
in place on the aluminium glazing bars and
ing glazed roofs to replace earliersystems
ing. Condensation channels are either open
which press against the glass to provide both
developed from greenhouse glazing. This
at the edges or are enclosed. Modem green-
a cushion for the glass as well as a water and
glazing system is still used in greenhouses for
house glazing is madefrom extruded alu-
air seal. The strength and stiffness of the glaz-
agricultural activities, but has poor thermal
minium sections with no thermal break, since
ing bar is provided by the central flat bar that
insulation, since their purposeis to absorb
high thermal insulation is not required, but
extends beyond the glazing line either inside
the heat from the sun rather than excluding
includes the condensation channels to avoid
or outside the glazing. Unlike curtain walling
it. The useof single glazing, with no ther-
water from drippingbelow. The horizontal
based systems, where the structural mullion
mal breaks and high air infiltration rates (by
joint between lapped glass sheets is sealed
extends on the inside face of the glass, with
curtain walling standards), make it ideal for
with either a sealant, typically silicone, or with
a pressure plate on the outside, greenhouse
agricultural use, but very poor for the use
continuous aluminium clips. Some green-
glazing has only clips on either side of the
in general building construction. However,
house systems still have lapped glass with no
control bar, allowing it greaterfreedom to
the concept of greenhouse glazing has been
seal at between the glass sheets, making it
extend both inside and outside the face of
developed into the highly insulated, air sealed
very economic, but not very airtight, which
the glass. The rubber seals are deep enough
and watertight glass roof systems used in
suits certain agricultural applications.
and soft enough to allow the bottom of the
contemporary buildings. An essential component of greenhouse
Ventilation in greenhouse glazing is provided at the eaves and at the ridge, while
glass sheetto lap over the top of the sheet below on the horizontal joints.
glazing that has been retained in modem
opening lights are used for more closely
glazed roofs isthe glazing bar, which cor-
controlled ventilation. Single glazed sheets
responds to a mullion in glazed walls. The
are held in place on their sides by supporting
greenhouse glazing bar has a condensation
them on the glazing bars and securing them
use the principles of traditional greenhouse
channel beneath of the glass to drain away
in place with continuous aluminium clips that
glazing, but incorporatethe techniques of
water that passes through the outer seal
snap onto the glazing bar. The aluminium
glazed curtain walling. Drained and ventilated
MCH
226
System details Systems for contemporary glass roofs
Vertical section 1:5, Typical capped glazing details
I
CD
I
3-D view of ridge in greenhouse roof
3-D detail of ridge
Vertical section 1:5, Ridge in greenhouse glazing
Vertical section 1:5, Typical ridge and valleydetails
CD
® Vertical section 1:5, Greenhouse glazing system showingtypical details
Vertical section 1:5, Clamping det ails for glass to glass connection
Vertical section 1:5, Clamping details for glass to polycarbonate connection
MCH
227
Roofs 03 Glass roofs I: gree nhouse glazing and capped systems
Vert ical section I : IO. Ridge detail
House in Lon don, UK. A rchit ect: Gianni Botsford Archi te cts
3-D view of capped glazing system with insulated ridge
Details I . Ext ruded aluminium glazing bar 2. Ext ruded alumini um transo m
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3. Ridge bar 4. D o uble glazed unit 5. T herm al insulati on 6. Pressure plate and capping 7. Rubb er seal
®
MCH
228
n II
8. A lumini um fiashing
Verti cal section I : I O. Capped glass roof
9. Aluminium clip on capping
with abutm ents
10, Extruded aluminium section
3-D view of capped glazing roof system
@
3-D cutaway of glass to glass comer detail in cpped glazing
3-D detail of capped ridge
systemsare used,with thenrnal breaks and
or pressure equalised, intemally. Water that
trapped on the to p edge of this horizontally-
double glazed units. Pressure plates rather
is able to find its way thro ughthe outer
set glazing bar, but this is soon blown away
than clips are used t o hold large glass units
seal drips into an intemal channel where it
by the wind or else evaporates. Any water
in place in capped systems, and toggle-type
is drained away safely to the bottom of the
that penetrates the outer seal is drained
plat es are used to provide flush joints in
roof, typically at the eaves. In smaller roofs
away throughthe intemal drain in the glazing
silicone based systems. This latter type is dis-
without eaves, where the roof angle changes
bar.
cussed in the next section on siliconesealed
from pitchedto vertical wall, rainwater is
rooflights, while this section focuses on pres-
allowed to run on down the wallto the base
principles of greenhouse glazing. The box
sure plate systems, so-called 'capped' glazing.
of the roof. At the 'fold' point of the roof the
section, or chosen profile of the typical glaz-
A typical system comprises glazing bars which
intemal drain in the glazing bar is continu-
ing bar is usually made deeper to take the
Ridges, like glazing bars, follow the main
are assembled on sit e in a grid of members
ous with the vertical wall, and the system is
higher structural loads of the ridge. Gutters,
that resemble the mullions and transoms of
drained at the base of the wall, which could
at both valleys and eaves, are very different
stick glazed curtain walling. The base of the
be a reinforced concret e slab at roof level.
to greenhouse glazing. Instead of lapping the
curtain wall, at the bott om of the extruded
Wh ile glazing bars runningdown the
glass into the gutter, the gutter profile (or
profile, may have an additional condensation
roof project above the surface of the glass,
downstand flashing) is clamped into one side
channel, as shown. This provision can also be
those running alongthe roof which hold the
of the horizontally-set glazing bar at the base
made by settingthe condensation channels
top and bottom edges of the glass in place,
of the pitched roof.
immediately beneath the glass. The glass is
require a method of allowingthe water to
set onto rubber-based air seals fixed to the
run over the junction. Some systems usea
glazing bar and is secured with a continuous
step at this point, without a pressure plate on
pressure plat e of extruded aluminium. A strip
top that would otherwise impede the pas-
of extruded EPDM is set between the pres-
sage of water down the roof. Other systems
sure plate and the glass to provide a weath-
usea pressure plate and cover capping with
ertight seal. As with glazed curtain walling,
chamfered edges that allow rainwater to pass
the glazing bars are drained and ventilat ed,
over it easily. A small amount of water is left
MCH
229
Roofs 03 Glass roofs 2: Silicone sealed glazing and rooflights
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3-D view of connection detail with gutter
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Vertical section I: I0 through roofiight showing typical details
System design
Details I. Extruded aluminium glazing profile 2. Pressure plate and capping
While capped systems, described in
channel is recessed into the gapat the edge of the unit usually usedto bond the unit
the previous section, suit pitched roofs,
together and to sealthe edges behind the
they cannot reliably be used on nominally
spacer. The adjacent spacer in the double
5. Thenmal insulat ion
flat roofs, where the roof pitch is usually 3°
glazed unit both keeps the glass at a fixed
6. Silicone seal
to 5°, This is mainly becausethe rainwater
distance apart as well as having desiccant
3. Mild steel support frame 4. Double glazed unit with recessed edge
7. Concrete base 8. Gutt er 9. Intemal finish
MCH
230
running down the roof cannot pass the
within it to absorb any residual moisture
horizontal glazing bars which project above
within the sealed cavity between the glass
the surface of the glass, The smooth, con-
sheets. The recessed aluminium channel is
tinuous finish required for flat glazed roofs
bonded to each glass sheet and also pro-
is achieved with a silicone seal between
videsthe edge seal to the completed unit,
glass panels that is set flush with the surface
as in a regular double glazed unit. The short
of the glass. The glass is clamped in place
lengths of pressure plate are then set into
with short lengths of pressure plate that are
the gap formed by the recessed channels of
recessed below the outer seal. The recessed
abutti ng glazed units, and are clamped to the
plates are secured to an aluminium channel
glazing bar wit h self tapping screws, typically
which forms an integral part of the double
at 300mm centres. The gap between the
glazed unit and which is continuous around
glazed unit is sealed with silicone, typically
its perimeter. The extruded aluminium
ISmm to 20mm wide, and with a backing
3-D view of typical ro oflight assembly with unca pped horizo ntal joints
strip or 'backing rod' behind it to form a backedge to the silicone seal. The glazing bar has its structural box or fin removed in order to fix it directly to
System details Since the advantage of silicone-sealed systems is of continuous glazed surfaces
a steel support frame. Altematively, an all-
uninterrupted by visible glazing bars, ridges
aluminium glazing bar can be used. As with
and valleys are treated only as folds in the
capped systems, small amounts of rainwater
surface of the glazing, for rainwater runs
that pass through the outer silicone seal are
across the complete sealed surface of the
drained away in the condensation channels
glass rather than being directed into gutters
set below the glass, within the glazing bar. In
set across its surface. The short lengths of
practice, silicone seals are very reliable but
pressure plate can be folded in the factory
are dependent upon correct workmanship
to the required angle, while the glazing bar
on site, so the condensation channel is often
forming the ridge isthe same as that used
not used in practice but serves as a second-
elsewhere on the roof, with some modifica-
ary chamberto support the inner air seals.
tions to the angle of the clips that hold the
Silicone-sealed glazing bars can be used in
inner EPDM seal in place. The edges of roofs
all directionsacross a roof, unlike capped
are also treated as folds, with rainwater usu-
systems, since the glazing bars presentno
allyallowed to run off the edge into a gutter,
barrier to the passage of water.
either just below the roof, or down to the
Dulwich picture gallery, London, UK. Architect: Rick Mather
MCH
231
Roofs 03 Glass roofs 2: Silicone sealed glazing and rooflights
Vert ical sectio n 1:5. Comer detail
Details I . Extruded aluminium glazing profile 3-D view o f co m er detail showing fo lded pressure plate t o
2. Pressure plate and capping 3. Mild steel support frame 4. D o uble glazed unit w ith recessed
achieve desired angle
edge
5. Thenmal insulat io n 6. Silicone seal 7. Concrete base 8. Gutter 9. Int em al finish
base of the glazed wall below the glazed
glazed unit to be coated or 'opacified' to
profilesare used for the vertically-set glazing
roof An advantage of this system is the
avoid the frame behind being visible through
bars running down the slope of a roof, while
ability of the roof to be continuous with a
the glass. This is often achieved by stepping
silicone-sealed glazing is used on horizontal
glazed wall in the same system with a simple
the glazed unit, with the outer glass extend-
joints to allow rainwaterto pass down it
'fold', wit hout reducing its weather tightness.
ingto meet the comer, while the inner glass
unimpeded by any projectingglazing bars.
Typically the wall is not very high, fonrning
stops at the glazing bar to allow the recessed
Junctions in silicone sealed glazing, such as
part of a largerglazed roof. Dust that is car-
aluminium angle to be bonded in its usual
edges of roofs and ridges, are fonrned in the
ried down off the roof during rain is washed
position adjacent to the glazing bar.The
same way, while the capped system follows
down the vertical glazing, rather than being
glass unit is secured in the same way, with a
the folds with continuous pressure plates
canried away in a gutter, but in practice
recessed length of pressure plate, while the
that are mitred and sealed at the folds. Butyl
glazed rooflights require regular cleaning to
outer glass is cantilevered t o meet the adja-
tape is used asan extra seal at folds, set
maintain their crisp appearance.
cent glazed unit at the comer.
between t he pressure plate and the outer
Folded comers are fonrned with either
An advantage of silicone sealed glazing
a single specially fonrned glazing bar, or wit h
is its ability to be mixed with capped glazing.
tw o glazing bars meeting. The recessed
Since both systems are drained and venti lat-
lengths of pressure plate are folded to fonrn
ed (pressure equalised), the same glazing bar
the required angle, and the silicone is cham-
can be used in a mixed roof system of flush
fered to fonrn a flat surface between the two
silicone joints and capped profiles. Although
meetingglass panels. Silicone is rarely used
this mix is done often for visual reasons, it
to makea sharp angle between the two
does allow for easily fonrned junctions with
double glazed units, as it is very difficult to
adjacent areas of roof in different materials,
achieve a straight line without the assistance
and for a mix of actual panels and glazed
of an additional metal angle bedded into the
panels in a single roof using a reliable drained
silicone. The altemative method of fonrning
and ventilated system. The most common
a roof edge requires the edge of the double
application of this method is where capped
MCH
232
EPDM gaskets. Cover caps are also mitred to give a crisp appearance.
-
3-D view of panel to panel junction detail w it hout capping
Vertical section 1:5. Panel to panel junction with capping
3-D view of panel t o panel junction detail with
3-D view of com er detail show ing insulat ed comer cov-
capping
ered by opaque glazing
MCH Horizontal panel t o panel junction w it h capping
233
Roofs 03 Glass roofs 3: bolt-fixed glazi ng
3-D view of ridge detail
3-D view of bolt fixed glazing with intemal fold
Details I. Structural steel support 2. Connector plate
3. Bolt fixing 4. Silicone seal between glass panels 5. Single glazed or double
7. silicon seal 8. Adjacent extemal wall 9. Insulation 10. Extruded metal cylindrical section I I. Roofconstruction 12. Concrete base
glazed unit 6. Support bracket
System design This method of glazing for roofs has
to support the same three panels of glass.
been adapted from the technique used for
This is achieved by settingthe beam inthe
glazed walls. where glass isfixed at points
middle of altemate glass panels. Brackets are
System details The essential component inthis glazing
with specially designed bolts rather than
cantilevered from the beam to support the
method. the bolt fixing. is made typically in
with a frame supporting the perimeter of
edge of the panel above as well as one side
stainless steel, and consists of several compo-
the glass. Bolt fixed glazing for facade con-
ofthe panel next to it. This method pro-
nents that fonrn the complete assembly. The
struction developed from earlier patch plate
vides greater visual transparency but requires
part that passes through the glass has either
glazing,where single glazed sheets of glass
largerbrackets. which in practice detract lit-
a disc on each side of the glass to clamp
are bolted together wit h mild steel brack-
tle from the increased effectof transparency.
the glass or double glazed unit together, or
ets. Glass fins are used to stiffen the glazed
The single tube section shown inthe
altematively is angled to fonrn a countersunk
walls to replacethe aluminium mullions. The
diagrams would suit only a short span. as in a
devicewithin the depth of the double glazed
L-shaped patch fittings bolt the fins and glass
rooflight, but large span roofs require deeper
unit. The countersunkfitting isset flush with
together. as well as bolting the glass to the
beams. usually fonrned as open trusses in
the outer face of the glass. and the face
supporting structure at the top and bottom
order to maintain the sense of transpar-
fixed disctype is set forward of the face of
of the wall.
ency at obliqueviewing angles. Triangulated
the glass. A polished stainless steel finish is
trusses provide both structure and support
mostly used on the outside in order to make
W here glazed walls are usually structurally supported by either top hung or bot-
for the glass. but tend to be visually heavy.
it easy to clean and maintain. In the face fixed
tom supported methods. the support of
Cable trusses are often prefenred, but they
type. which iscunrently the most commonly
glazed roofs is by trusses, steel sections or
require a ring beam around the edge of
used fixing. the inner disc screws over the
purlins that span across the roof opening.
the glazed roof to fonrn a tensile supporting
threaded shank that fonrns part of the outer
For nominally flat roofs, the most common
structure like a tennis racquet. The cable
disc until it istight up to the inner face of the
arrangement isa supporting beam set under
trusses. always intension. require an equiva-
glass. The threaded shank projecting into the
each glass joint. so that bolts are supported
lent sunrounding structure in compression
building isable to rotate about a ball bearing
on each side of the beam by a short bracket.
to transfer the loadsto the main building
where it meets the inner face of the double
structure.
glazed unit. This allows the double glazed
Only halfthe number of beams are required
MCH
234
3-D view of bo lt glazed roof system
Vertical section & elevations I :25. Bolt fix ed roof w ith folded pro file
3-D of valley detail
Vert ical section I : 10. Intem al fold
00JI
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eD 3-D view of bolt fixed system
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Hori zont al section I :25. Typical clamp assemb ly
MCH
235
Roofs 03 Glass roofs 3: bolt-fixed glazing
Vertical sections I:10. Bracket support
Vertical section I:IO. Connection to roof deck
Tower Bridge House, London, Uk. Architect: Rogers Stirk Harbour + Partners
unit to rotate up to around 12° under wind
common joint width (in elevation) that
load and associated structural deflections.
allows for both structural movement and
made as an outer silicone seal wit h an inner
This swivel joint is essential in avoidingthe
the slight variations in the size of the glass
backing rod of extruded EPDM. The gasket
over stressing of the glass under full wind
panels. Unlike capped roof glazing systems,
has projectingflaps on each side to form a
load that would otherwise result in breakage
the entire double glazed unit is visible from
'fir tree' section which prevents any water
of the glass unit. The threaded shank is then
both outside and inside, the edges are not
that penetrates the extemal seal from reach-
used to clampthe complete bolt fixingto a
set behind pressure plates that conceal any
ingthe inner face of the seal. This EPDM
support bracket with either threaded discs
variations in glass panel size. Joint widths up
gasket also serves asan inner air seal, and
or nuts. The visible thread in the shank can
to around 28mm, which is deemed close to
provides a crisp appearance of sharp lines in
be either left exposed, or be covered wit h
the maximum practical joint width for the
the interior face of the glazed roof.
threaded sleeves and stop ends. This bolt
adhesion of silicone sealant in a regulardou-
type is used regardless of the orientation of
ble glazed unit, is used where brackets pen-
the roof, whet her flat or pitched. In common with other glass roof types,
etrate the outer seal from insidethe roof to outside. If required, these brackets are
the inner glass of a double glazed unit is usu-
used to support extemal sun shading and
ally made from laminated glass. In the event
maintenance equipment. These brackets
of a double glazed unit being broken, the
are usually in the form of flat plates that are
inner laminated sheet remains intact, while
welded to the intemal supporting structure,
the broken piecesof the heat strengthened
and project through the joint. Although an
or fully toughened outer sheet come to rest
additional lip around the projecting plate
on top of the damaged, but intact, inner
may provide additional protection to water
sheet. The double glazed units are first fixed
penetration between the silicone and the
and adjusted to form even joint widths
bracket, in practice it has been found that
between all the units. Joints of 20-28mm
this detail performs well if the seal is applied
are used, though around 20mm isthe most
to a good level of workmanship.
MCH
236
Seals between double glazed units are
3-D view of base stand connectionto roof deck
Louvre gallery, Paris, France. Architect: I M Pei
® 3-D view of underside of bolt glazed roof system
\ L
_
® - ® Vertical section I:IO. Base upstand junction
Vertical section I:IO. Junction wit h adjacent wall
Vertical section I:10. Upstand at base
MCH
237
Roo s 03 Glass roofs 4: bo nded glass rooflights Details I, Silicone bo nd 2, Mild steel support frame 3, Single glazed laminat ed glasspanel 4, Silicone seal 5, Co ncret e base 6, Insulat ed met al panel 7, Fold ed met al fiashing 8, Reinforc ed conc rete suppo rt frame 9, Fo lded alumunium pro t ective cover
Plan I :20 of typical ro ofiight layout
10, Stee l aluminium suppo rt shoe I I, St nuctu ral glass beam
CD
3-D view of ty pical roo f light assembly
,
I>
= Vert ical sectio n I : I0, Base upstand, Junction w ith adjacent mat erial
Vert ical sectio n 1:5 through roofiight showing t ypical details
CD
System design The method of silicone bonding glass to
be extremely difficult to fabricate, The rec-
in glazed curtain walling to provide visually
tangularroofiight shown is bonded together
smooth glass facades with no visible cap-
without a supporting structure; the glass pro-
pings, The use of silicone sealed roofiights
vides its own support. The fiat monopitch
can be taken a step further to become a full
roofiight is bonded to a frameto provide
bond without the need for the mechanical
a small roofiight from one double glazed
restraint of pressure plates, In silicone bond-
roofiight, with laminated glass sheets used to
ed roofiights, the glass is glued to a support-
fonm a surface which can be walked upon.
ing frame, The glue is also the extemal seal.
Similar to a glass fioor used inside a building,
This technique is useful for small roofiights,
it must also take heavier traffic loadings and
where cappings would be very difficultto
be weathertight.
238
The generic conical roofiight shown has
upon, where the roofiight is an extemal glass
a lightweight steel frame used to support
floor,
double glazed unitsthat fonm a roofiight.
The generic conical roofiight shown has
MCH
both vertically and horizontally, which would
aluminium framing is well developed for use
fabricate, and in roofiights which are walked
3-D Details showing glassto glass junctio ns
cover caps that would have to be curved
The structural frame comprises box sections
curved double glazed units bonded to an
set vertically, held in place by thin tube sec-
aluminium frame, Silicone bonding avoids
tions running horizontally to fonm a circle,
3-D view of glass beam with central steel support beam
3-D view of underside of glass beam and ste el suppo rt beam 111111111111111111111111111111111111111111111111111111111111111111111
~ ' /-
Vertical section I: IO. Support systems for roofii ght
" " 0"'1
3-D det ail of st eel support beam
"v' The glass panels are supported on steel fi at sections which are welded to the horizontally set tube section. The glass is levelled on
is constructed without a supporting frame.
blocks set onto the horizontal fiat section,
Mechanical restraint is provided at the
and the si licone is applied to the joint. At the
comers in t he fonm of pressure plate clips.
base, the horizontal metal section projects
The double glazed units at the corners are
out to fonm a fiash ing over the upstand in
fabricated with a recessed groove on the
which the roofi ight is set. An additional inner
two sides of the panel fonming the corner
metal upstand can be provided with another
in order to receive the clip. An alternative
si licone seal ifthere is risk of future flooding
method is to fix the metal clip to the outside
from blocked rainwater outlets, for example.
of t he glass at the comer. This avoidsthe
The waterproof membrane for the roof slab
need for special ly made comer pieces but it
is continued up the upstand and is bonded
does fonm a visible fixing. The modest size of
to the base of the horizontal section that
this roofiightallows the horizontally-set glass
supports t he glass. This provides a complete
to span from side to side with no additional
"
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top of the wate rproof membrane. The generic rectangu lar roofi ightshown
"
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Vertical sectio n I : IO. Junctio n with adjacent w all
~ @
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~
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seal from the glass to the roof membrane,
support. The comers of the roofl ightare
with the metal flashing providing both a pro-
stiffened by short lengths of pressure plate
tection to this seal and a means of conceal-
which holdthe glass in place. The glass has a
ing the closed cell thenmal insulation set on
specially shaped groove in the depth of the
@
Vertical sectio n I: IO. Bracket support
MCH
239
Roo~03 Glass roofs 4: bonded glass rooflights
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Vertical section I:10 through bonded glass roof light showing typical details
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o Vertical section 1:5. Typical comer detail
0)
Horizontal section 1:5. Typical comer detail
Vertical section 1:5. Bonded glass to glass connection
Vertical section I:5. Typical connection to roof
double glazed unit, to which the pressure
decking is in development and will no doubt
upon the individual design. Here steel plate
platesare fixed. Comer joints have an outer
become much more common over the next
is used to provide a beam instead of lami-
comer piece of folded aluminium which is
10years.
nated glass, a steel flat is welded to the top
silicone bonded either to the face of the
The glass used is laminated, in common
of the beamto fonm a T-section that gives
adjacent glass units, or is folded at 90° to
wit h other rooflights, both to avoid the pos-
enough bearing for the glass deck. The ends
bond it to the side of the unit. Glass-to-glass
sibility of any falling objects from penetrating
of the glass beams are supported by a metal
joints between horizontally-set units have a
the glass on impact, as well as preventing
shoe support, made from either mild steel
silicone seal wit h an aluminium angle set on
damaged glass from falling immediately into
or aluminium. Stainless steel is used where
the inside face to provide a second seal.
the space below. The glass is set into a series
conrosion is an essential consideration of the
of extruded aluminium anglesto which it is
design. The metal shoe is bolted backto the
bonded on its underside. A gap between the
supporting structure or reinforced concrete
System details
frame and the top of the glass is sealed wit h
floor slab. The gap between the edge of the
accessible roof decks have been in use over
silicone of a different type. An additional
glass deck and the adjacent roof finish mate-
the past 10years. Previously used only
condensation channel is set below the glass
rial is madewith a silicone seal.
inside buildings for walkways and stairs, they
to catch any water that penetrates the sili-
are now beingused as fully waterproofed
cone seal, or any water that passes through
external decks, manufactured as proprietary
a damaged joint.
Rooflights fonmed as nominally flat,
systems. Single glazing is used, since double
The details here show altematives for
glazed units are difficult to use asa result of
both steel beam and glass beam supports to
solar gain around the edge of the unit, where
the glass panels. A typical rooflight is shown
the glass is exposed to the outside, but is
with glass panels 2400mm x 1200mm in size.
supported on its underside, allowing heat to
The supporting structure has a glass beam
enter but not to escape. W here blackcol-
set in the centre, spanning the full length of
oured edge 'frittiog' is used, the situation is
6000mm. Its depth is approximately 600mm,
made difficult. However, double glazed roof
but the beam depth will vary depending
MCH
240
3-D cutaway of t ypical com er detail
3-D cutaway of t ypical rooflight assembly
3-D cutaway of t ypical junction w ith roo f
ED
3-D detail of connection between glass beam and concret e w all
3-D det ail of junction betw een glassand steel support beams
3-D view looking up at int erior finish at edge of glassbeam and concrete base
Details I Silicone bon d 2. Mild steel support frame 3. Single glazed laminated glass panel 4. Silicone seal 5. Concrete base 6. Insulated metal panel 7. Folded metal flashing
8. Reinforced concrete support frame 9. Folded almunium protective cover 10. Steel aluminium support shoe I I . Structura l glass beam
3-D view of junction at edge of glassbeam and steel support
MCH
24 1
Roofs 03 Concrete I: co ncealed mem brane
3-D overview of a concrete roof w ith a concealed membrane
Det ails I. W aterproof membrane 2. The rmal insulation 3. Co ncrete de ck 4. Paving slabs 5. Smoo th pebbles 6. Parapet cop ing 7. Rainwater o ut let 8. Slot dra in 9. O pen ing for overf ow
System design Bitumen hastraditionally been used as a
dimensional stability andtensile strength.
of the building. An outer protective layer
wat erproof layer, applied while hot in liquid
This reinforcement often allows the mate-
is added for vulnerable locations such asat
fonm onto a concrete roof slab. As it cools it
rial to be folded through 90°, making its use
gutters and at upstands.
hardens, fonming an impervious membrane,
considerably easier, where angle fillets are
but will soften again if heated by the effects
not required.
of solar radiation. For this reason, in order to
With the development of much thinner
System details Concealed membrane roofs are typi-
keep the material cool, bitumen membranes
membranes in thenmoplastics and elastom-
cally in 'inverted' roof configuration with
are concealed by smooth pebbles or pav-
ers, together wit h their competitive costs,
either open joints or sealed joints in the
ing slabs, usually wit h thenmal insulation set
there have been considerable efforts made
top layer that coversthe thenmal insulation,
between the bitumen andthe pebbles or
by manufacturers over the past 20 years to
usually paving. In the open joint version, the
paving. Traditional bitumen roofs are usually
makethe bitumen layers thinner,to reduce
membrane, bonded to the concrete slab, is
laid in two layers, with an overall thickness
the material required while enhancing its
covered by a protection layer, with closed
of around 25mm. One of the limitingfac-
properties of strength and flexibility. This has
cell, rigidthenmal insulation set on top . A
tors with bitumen is foldingthe material at
been achieved by replacing the thick two-
polyesterfilter sheet is set on top, wit h pav-
a comer or edge. W hen the material tums
layer method wit h a mixture of thin layers,
ing or smooth pebble ballast on top to hold
through a right angle from the horizontal
still applied in hot liquid fonm on site, but
the insulation in place as well as to walk on.
roof to a vertical parapetwall, it can pass
reinforced wit h an elastomeric sheet, usually
Pebbles are 20mm - 40mm diameter, while
through a maximum of 45° in a single fold.
bedded between the layers. This is typically
paving slabs are around 600 x 600mm in
For this reason 45°angle fillets are used to
two layers, each 3mm thick with reinforcing
size and 30 mm - 40mm deep. In the sealed
make a 90° tum from roof to wall.
layers bedded into the material. This allows
joint configuration, the bitumen membrane
the bitumen to accommodate both small
with its protection layer has a drainage layer
are concealed beneath roof finishes are typi-
amounts of movement at these junctions, as
on top, onto which is laida minimum 65mm
cally a combination of bitumen-based sheet
well as the sharp fold in the material, which
sand/cement screed, usually reinforced or
mixed wit h synthetic rubber to give flex-
creates a weakness in the membrane which
made sufficiently thick to avoid cracking both
ibility combined with a reinforcement to give
might otherwise be damaged duringthe life
in the screed and the sealed paving above.
Modem bitumen-based membranes that
MCH
242
CD
CD -- --c.!F - -' -CD
CD
Ve rtical section I:10. Rainwater o utlet
3-D detail of rainwate r outlet
CD 3-D view of parapet and rainwater out let
-,
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.
CD '(
Vertical section I: I0 , Parapet and rainwater o utlet
MC H
243
Roofs 03 Concrete I: concealed membrane
3-D detail of concrete upstand
Persistence W orks, Sheffield, UK. Architect: Fielden Clegg Bradley Studios
Vertical section I: IO. Concrete upstand
Paving slabs or blocks are bonded to the
bitumen based material, or increasingly, a
screed with mortar and grouted.
rubber-based strip.
Expansion joints between concrete Vertical section I: IO. Junction of extemal wall and roof slab
slabs of widths between around IOmm to
as possible with the adjacent areas of roof
50mm are fonmed by stopping the material
to allow water to drain freely from the roof.
each side of the joint and setting a rubber-
The reinforcing membrane is sometimes
based strip that dips into the gap between
folded down into the gap, separat ed from
the slabs, linking the membranes into a
the membrane below wit h a foam backing
continuous seal. The joint is protected and
rod. It can be difficultto drain water from
reinforced with an additional layer, either
this groove at the edge of the slab unless
fiat and bonded on one side only, or fonmed
water at this lower level can discharge into a
as a folded, S-shaped cover that folds back
rainwater outlet.
over itself, held in place by an additional
CD- - - Vertical section I:IO. two-way drain outlet
MCH
244
The top of the joint is finished as level
In fonming parapet upstands, an essen-
protection sheet on top . The gap between
tial requirement is t o keep the waterproof
the membrane, dipped into the joint, and
membrane as well protected from the
the reinforcement cover is filled with a foam
effects of the sun as elsewhere on the roof.
backing rod or tube, as used in the glass
For this reason, thenmal insulation is applied
joints of bolt fixed glazing. The material used
to the inside face of the parapet, even if
for the reinforcement is either the same
this has no direct benefitto the passage of
CD
CD
3-D detail of ballustrade w it hin ro of system
3-D detail of roo f parapet
/)-_ _----'.c=-=..::"--_
CD Vert ical sect ion I : IO. Expansion joint in concrete slab
3-D det ail of ex pansion joint in concret e slab
heat th rou gh t he building. Th e membrane
of the waterproofing layer. T he base of the
is t umed through a full 90° as shown in th e
rainw ater outlet is fixed to the concrete slab.
drawings. but an angle fillet is required by
The w at erpro of membrane is dressed dow n
so me manufacturers t o limit t he angle of
int o t he top of the rainwater outlet and the
any fo ld to 45°. A reinforcing strip is usually
upper part of the rainwater outlet is bolted
added where a 90° fold is made.
down onto the part already fixed and sealed.
Plint hs which are fomned as short col-
CD Vert ical section I : IO. Parapet detail
The geotextile sheet is wrapped around t he
umns for the support of roof-mounted
outl et to avoid dirt and debris being washed
mechanical equipm ent or balustrades are
int o t he rainwat er drainage system.
wate rproofed in a similar way to a parapet upstand. The membrane is fold ed up t hrou gh 90° fro m the roo f level and is
J.
-·,, 0-
fomned t o cover the complete plinth . Th e themnal insulation extends across the complete plinth to prevent a themnal brid ge through the roof constructi on.
CD
CD
Rainwat er outl ets are set at t he level of t he wate rpro of membrane . drained at both
Ve rt ical section I : IO. Base of balustrade
the level of the sealed paving and t he level
MCH
245
Roofs 03- - - - - - - - Concrete 2: exposed membrane
3-D overv iew of concrete roof with an exposed memb rane
System design wide range of exposed membrane materials
with ballast to the concrete deck beneath.
for flat roofs which are not visible from
Exposed membranes have been used
available to suit different budgets and indi-
Developments in these materials have led to
below, but this has changed in recent years
vidual roof designs.
them being used on timber decks and pro-
as membranes are produced in increasingly smooth and regularfinishes. Because of their
Polymer-based membranes have the main advantage of an abilityto be cut and
filed metal decks in addition to the concrete decks discussed here. Both thermoplastic
lightweightnature, they are often used in
formed to complex shapes, allowing them
and EPDM membranes can be welded
conjunction with lightweightroofs such as
to take up shapes precisely. sometimes pre-
together to form a continuous waterproof
profiled metal deck and timber. This section
formed in the factory before being delivered
sheet. While both material types were glued,
considers their use in concrete construction,
to site. Single layermembranes are very
there is an increasing use of hot air welding
though the same principles of waterproofing
practical on roofs with a large number of
methods, which avoidthe need for flame
can be applied to these other materials.
penetrations, typically in commercial build-
techniques or adhesive bonding methods
ings where mechanical ventilation equip-
that can be both slow and can damage adja-
ment is regularly being modified or replaced
cent work duringtheir application. In hot air
The introduction of polymer-based membranes provided economic waterproofing materials that are more flexiblethan their
duringthe lifetime of a building. Single layer
welding, a jet of heated air is used to soften
bitumen-based predecessors. The increased
membranes are made from either elasto-
the materials and weld them together,
flexibility of the new sheet materials allowed
meric materials, typically EPDM, or from
applied from a range of tools that are either
for greater amounts of movement between
thermoplastic materials, typically plasticised
hand held or fully automated, depending on
adjoining components and assemblies, allow-
PVC (PVC-P). Elastomeric materials are
the application.
ingthe detailing of junctionsto be relatively
very popular in the US while thermoplastics
straightforward in forming a reliable weath-
are preferred in Europe. EPDM (ethylene
fibre sheetor polyesterfabric. These lay-
ertight roof membrane. As a result of these
propylene diene monomer) is a flexible and
ers are bonded into the material. The glass
developments, polymer modifications were
elastic material that has the appearance of a
fibre provides dimensional stability, making
also made in the earliergeneration bitumen-
synthetic rubber. EPDM is manufactured in
it more stable for bondingto the substrate.
based materials to makethem more flexible,
the limited colours of black, grey and white.
The woven polyesterfabric, used in tent
in order to compete with the polymer-based
Both elastomers and thermoplastics can
sheet materials. As a result there is now a
MCH
246
be mechanically fixed, bonded or secured
Membranes are reinforced with glass
membrane structures, has hightensile strength to resist wind loads.
Details I.Waterproof membrane 2. Thenmal Insulation
3. Concrete deck 4. Paving slabs 5. Smooth pebbles 6. Parapet coping 7. Rainwater outlet 8. Opening for overflow 9. Balustrade 10. Pipe or duct I I. Extemal wall 12. Rooflight
Tenerife Concert Hall, Spain. Architect: Santiago Calatrava.
(( r:
tiIf( (-r-n
.J.J.J .JJ~'~'.J.JJ
Vertical section I:10. Pipe penetration
3-D detail of pipe pentration.
@
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Vertical section I: I0 Junction of extemal wall and roof slab
3-D detail of junction between roof slab and extemal wall.
MCH
247
....----Roofs 03- - - - - - - Concrete 2: exposed memb rane
Vertical section I: IO. Rainwate r outlet (ballust ed met hod)
3-D detail of rainw ater out let w ithin exposed membrane roo f
Verti cal section I: IO. Rainwat er outlet (bonded metho d
place. The pressure plates are fixed by bolt s
systems still bond the membrane at points
membrane is a concrete deck with a vapour
A typical build-up for a single layer
at centres along their length to the substrat e
only rather than across the entire surface of
barrier set on top, with thermal insulation
below.
the membrane, but this is dependent upon
above that, sealed on top with a single layer membrane. PVC-P membranes are typically
the wind load and the proprietary system
System details
used.
I.Smm - 3.0mm thick, while EPDM mem-
Membranes can also be secured by
Bonded membranes have a visually
branes are typically I.Omm - l.5mm thick.
point fixings rather than by pressure plates.
smooth appearance, making them suit able
SO-7Smm diameter rigid plastic discs are
where the roof surface is seen from points
used to hold the build-up in place. These are
around the building. This fixing method still
The mechanically fixed method is suit ed to applications with high wind uplift forces, as bonded systems tend to be limited by
set at centres to suit the design wind loads.
requires mechanical fixing at the edges, and
the bonding strength of the vapour barrier
The closed cell rigid insulation istypically
around openings such as rooflights.
to which the membrane is itself bonded
made in panel sizes of 1200mm x 2400mm
through the thermal insulation layer, which
in thicknesses from 2Smm to IOOmm.
is typically made from expanded polystyrene
Membranes can be bonded or mechanically fixed to parapet upstands. The fixing
In the bonded fixing method the
method that is used on the main area of
board. The vapour barrier is loose laid on
exposed membrane of the vapour barrier
roof is usually continued on these vertical
the concrete deck and thermal insulation is
is usually bitumen-based and is bonded to
areas. W ith mechanical fixing t he pressure
then mechanically fixed through this barrier
the deck.Joints betw een the vapour bar-
plate can be fixed either to the upstand
to the deck beneath. The spacing of the fas-
rier sheet s are lapped t o avoid any risk of
or to the flat roof area. The pressure plate
teners varieswith the design wind loads. A
vapour passing through the roof structure
forms a junction between the membrane
separating layer of glass fibre sheet is usually
from inside the building. The thermal insula-
sheet forming the upstand andthe mem-
laid onto the insulation with an outer single
tion is then bonded t o the vapour barrier.
brane sheet of the roof Intermediate pres-
layer membrane. The membrane is mechani-
Insulation can also be mechanically fixed
sure plates are applied horizontally on the
cally fixed wit h pressure plate bars, similar to
with pressure plates to the concrete deck
upstand when its height exceeds around
tho se used in glazed curtain walling systems
beneath. The membrane is then bonded
SOOmm, depending on the specific material
to hold t he glass in place. Bars form strips of
to the insulation with a continuous layer of
used.
pressure plate to hold the roof build-up in
bonding adhesive on its underside. Some
MC H
248
Canary Wharf underground stat ion, London, UK. Architect: Foster and Partners
...--
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Vertical section I:IO. Upstand for balustrade
3-D detail of upstand
I
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3-D detail of low parapet
CD
-
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Vertical section I:IO. Low parapet
MCH
249
Roofs 03 Concrete 3: planted roof
Vertical section I:IO. Heavy planting. Rainwater outlet. 3-D detail of rainwater oult et in heavily planted roof
@
3-D detail of pipe penetration in heavily planted roof
3-D detail of cill junction in heavily planted roof
on a roof accessible to building users, but are seen from vantage points around the building. Light planted roofs have plants and Vertical section I:IO. Heavy planting. Pipepenetration.
flowers that require little maintenance and
System design Concrete decksused for planted areas
do not usually have an irrigation system to supply wat er at controlled times, relying on
can be waterproofed with either a con-
rainwater and modest amounts of wat ering
cealed membrane or an exposed membrane
during maintenance at specific times of the
asdiscussed in the previous sections. Planted
year. These lightweight planted roofs suit
roofs are of two types: light planted and
a lightweight deck, such as a thin concrete
heavy planted. Unlike other concrete roof
shell, although profiled metal decksare
types, planted roofs are not always insulated
commonly used as substrates. Maintenance
asthey often form the roof of underground
access is provided by the pebble strips at the
structures such as car parks, providing a
roof edges or by individual paving slabs that
planted roof at ground level.
avoid the need to walk across the planting.
Light planted roofs have resilient plants
Heavy planted roofs permit a wide
that require little or no irrigation, and that
variety of plants, shrubs and trees to grow
Vertical section I:IO. Heavy planting. Cill
will grow in a thin layer of soil or organic
on a concrete roof deck. Due to the size
junction.
growing medium. They are not usually used
and intensity of the plantingthey require an
MCH
250
3-D overview of concrete roof with heavy planting
3-D detail of parapetjunction in heavily planted roof Vertical section I: 10. Heavy planting. Low parapet.
automated irrigation system, usually from pipes set into the soil that provide a trickle
drainage it is estimated by manufacturers of proprietary systems that 50% to 90% of rain-
water feed t o the soil at specific times which
fall is retained in planted roofs, but this varies
may vary duringthe course of the year.
considerably with local climate conditions
Heavy planted roofs require regularmainte-
and rainwater drainage provision.
nance, provided by paved paths or by areas of grass. Both light planted and heavy planted
System details
Details
8. Vapour barrier
I. Light vegetation
9. Concrete deck
2. Heavy vegetat ion
10. Smooth gravel
3. Soil/growing medium
II . Coping
4. FiIter sheet
12. Pipe/ duct
5. Drainage layer
I 3. Supply pipe
6. Waterproofing layer
14. Rainwater outlet
7. Thenmal insulation
15. Wall cladding
Both light planted and heavy planted
roofs have drainage layers beneath the
roofs have a similar build-up, comprising typ-
growing medium that hold wat er and
ically a top layer of planting, with a growing
release it backto the plants when required.
medium or soil beneath. A filter layer is set
This allowsthe soil depth to be much less
underneath, and below this, a drainage layer
than that which would be required for
and moisture mat. Beneath this lowest layer
older landscaping methods, where the soil
is set thermal insulation if required. Although
was expected to hold all the water. The
planted roofs provide a limited amount of
reduced depth of soil allows planting to be
thermal insulation from the soil, in practice
considered for concrete roof structures that
this is reduced due to the varying amounts
would require no significant strengthening to
of wat er held wit hin the soil. A root barrier
receive the added weight of soil. In terms of
is set beneath the insulation to protect the
Laban Centre, London, UK. Architect: Herzog and de Meuron
MCH
251
Ro o~03----------'"
Concrete
3: planted roof
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Section I:IO. Light planting. Rainwater outlet
3-D detail of rainwater outlet in lightly planted roof
Section I:10, Light planting. Low parapetjunction
3-D detail of low parapet in lightly planted roof
wat erproof membrane, that is the bottom
age layer. The mat is made from a durable
drainage layer to provide greater water stor-
layer, bonded to the concrete roof deck.
fibre that retains moisture and nutrients as
age. The soil depth, in excess of 150mm,
The root barrier is sometimes bonded to
well as serving as protection to the root
requires an automatic irrigation systemto
the waterproofing layer, usually when the
barrier beneath. It is not used in inverted
provide a reliable water supply coverage of the complete roof
complete build-up is a single proprietary sys-
roof configurations. In inverted roofs, a root
tem. To prevent the passage of organic mat-
barrier is set immediately below the insula-
ter and fine particles into the water drainage
tion to protect the waterproof membrane
ples apply to planted roofs as discussed in
system, a filter sheet is set undemeath the
fonnning the lowest layer. This layer prevents
the previous sections. The waterproofing
planting. This sheet is lapped up the sides of
planting roots from damaging the water-
extends a minimum of 150mm above the
the planting,where it meets an upstand, to
proofing. In wannn roof construction, the
level of the planting, providing a continuity
the level of the planting.
wat erproof membrane is set on top of the
from the roof membrane to the fiashing at
The drainage layer beneath the filter
At upstands and eaves the same princi-
thennnal insulation, positioning the insulation
the top of the upstand or to the adjacent
sheet retains wat er that drains through
within the building envelope. A vapour bar-
wall construction. Upstands for parapets
the planting. W at er is retained in profiled
rier is set between the thennnal insulation
and door sills, highwalls and roofiights are
troughs in a typically polystyrene egg-crate
and the concrete deck. In this configuration a
fonnned by extending the waterproof filter
shaped tray that releases wat er back to the
moisture mat is set between the wat erproof
sheet and root barrier up to a minimum of
planting. This method also perfonnns satis-
membrane and the drainage layer above.
150mm above the level of the soil or grow-
factorily on sloping concrete roofs. Excess
The soil depth in light planted roofs
ing medium. The visible membranes and
wat er is drained away through gaps between
ranges from 50mm to around 150mm.
sheets are concealed wit h thennnal insulat ion,
the drainage trays. The egg-crate fonnn allows
W ater is stored in the growing medium and
and typically either paving tumed on edge, as per the paving used for adjacent access
aerat ion, pennnitting the soil to absorb the
drainage layer, making it efficient in mild,
water stored here. In drier months, water
temperate climates. Lightplanted roofs can
paving, or a metal sheet to match that of
diffuses up through the soil to the plant
be grown on both nominally fiat roofs and
the parapetcoping where a metal coping is
roots. A moisture mat is often set under this
on sloping roofs with a pitch up to 25° to
used.
layer to catch wat er that runs off the drain-
30°. Heavy planted roofs have a deeper
MCH
252
3-D overview of concrete roof wit h light (sedum) planting
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3-D detail of ro oflight upstand in light ly planted roof
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3-D detail of pipe penetration in lightly planted roof
Section I:I0. Light plant ing. t wo- way outlet
3-D detail of t wo- w ay outlet in lightly planted roof
MCH
253
Roofs 03 Timber roofs 2: fiat roof: bitumen-based sheet
3-D overview showing typical flat t imber roof construct ion with insulation between roof joists.
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Section I : 10. Flat roof w it h rigid insulation above roof structure
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Flat timber roofs are described as being
tion, on the wanrn (in winter) side of the
tion. In the wanrn roof configuration, thenrnal
insulation, with a dry wall or intemal lining
insulation is set on top of the timber deck,
board set below this. In both wanrn and cold
which is protected by a wat erproof layer set
roofs, the vapour barrier avoids the passage
onto its upper face. A vapour barrier is set
of damp air up into the thenrnal insulation
between the thenrnal insulation and the tim-
where interstitial condensation can fonrn that
ber deck. The roof build-up is not required
might damage the intemal construction of
to be vent ilated as the timber structure is
the roof.
maintained at near intemaltemperature
Section I : IO. Low parapet w all w it h drain outlet
MCH
254
A vapour barrier is set beneath the insula-
in either 'warm' roof or 'cold' roof configura-
In a mastic asphalt waterproofed wanrn
conditions. In the cold roof configuration the
roof. thenrnal insulation is set on top of the
wat erproof layer is set directly onto the tim-
timber deck, with an asphalt layer on top of
ber deck. Thenrnal insulation is set beneath
this. A separation layer is set between the
the timber deck, in the voids between the
asphalt andthe thenrnal insulation. A vapour
timber joists and air is allowed to circulate
barrier is set between the thenrnal insulation
in the void to provide ventilation that avoids
and the timber deck. In the mastic asphalt
the possibility of rot fonrning in the timber.
cold roof configuration, the asphalt is set
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Section I: 10. Low parapet wall
Details I. Bitumen based sheet
2. Plywood sheet 3. Rigid thermal insulation 4. Vapour barrier 5. Softwood joists 6. Dry lining/drywall intemal finish 7. Metal Flashing 8. Timber upstand 9. Extemal Wall 10. Angle fillet I I. Proprietry skirt flashing 12. Rainwater outlet 13. Paving bonded to bitumen
3-D view of expansion joint in typical timber flat roof construction
directly onto the timber deck, wit h a separat -
greater strength, flexibility, a higher melting
ing layer beneath the asphalt.
point and UV resistance. However, the use
Mastic asphalt, usedto form a continu-
of this material is set to continue, mainly
ous wat erproof covering on flat or sloping
a concealed membrane, but its use as an
roofs, has polymer additives in some types
exposed membrane is discussed here since
to provide stability at the relatively high
this application is much more common in
temperatures experienced when exposed
timber constnuction. Mastic asphalt is laid on
to the effects of the sun, aswell as providing
rigid substrates, typically reinforced concrete
flexibility ofthe material at low temperatures,
decks, but its use as an exposed membrane
which allows it to take up movements in the
on a timber deck is set to continue, particu-
substrate. Asphalt is applied in a hot liquid
larly as a result of additives which make the
form on site, allowing it to form a homoge-
material more flexible than was previously
neous material at complex junctions such as
the case.
at upstands, roof penetrations and changes in
based sheet
In warm roof constnuction, a protective
level. It was used more commonly 25 years
surface is usually applied to all exposed areas
ago, and its popularity is being challenged by
wit h a solar reflective paint, stone chippings
single layer sheet membranes, which have
or thin paving slabs which are bedded into
Private residence, London, UK. Archit ect: Lynch Architects MCH
255
Roofs 03 Timber roofs 2: fiat roof: bit umen-based sheet
3-D view of drain outlet in t imber roof
3-D section t hrough roo f show ing pipe penetrat ion and step. Timber roo f w it h low parapet and layer of shingle
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MC H
256
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3-D detail showing step in roof construction
3-D detail showing pipe penetration through roof
cally fixed and sealed, or bonded, to the duct
the asphalt surface with a proprietary adhe-
Trims to verges and eaves are formed
sive. A single layer of IOmm - 14mm stone
with a GRP or aluminium trim in order to
or pipe creating the penetration. An addi-
chippings is used as permanent surface pro-
support the bottom edge of the asphalt.
tional secondary seal, formed typically wit h
tection for asphalt. The chippings are usually
Some installations use no trim at all, but the
either EPDM or metal sheet, forms a second-
bonded to the asphalt after the asphalt has
edge becomes vulnerable to damage and can
ary seal to this penetration.
cooled, with a bitumen solution to provide
result in a visually uneven appearance. W hen
only a limited bond. This allows the chip-
the asphaltedge is terminated by a gutter, a
ated within the timber deck since asphalt can
pings to be removed easily at a later date for
metal flashing can be set under the bottom
be laidto suit a complex geometry without
repair and maintenance work
of the asphalt.
the need for joints in the material. W here
Verges can be formed by creating an
System details
Gutters can be formed t o any shape cre-
the gutter is formed as a parapet gutter at
asphalt upstand, built to a height of around
the base ofthe tiled roof, the asphalt is car-
SOmm to suit the expected flow from the
ried up over the tilting fillet of the tiled roof.
set vertically, or at a steep slope, the mate-
roof. An altemative detail is to stop the
Rainwater outlets are formed by setting the
rial is laid in three coats. The first coat is very
asphalt at the edge of the roof andterminate
out let at the level of the structural deck. The
At upstands, where the asphalt is usually
thin in order to key in the substrate, then
in a metal strip so that the asphalt cannot be
asphalt is stepped down with 45° folds down
two further separate coats are applied to
seen from below, but in practice it can be
into the rainwater outlet, and the metal grat-
give an overall thickness of around 20mm. In
difficult to achieve a reliable seal between the
ing and cover is fixed down onto this. The
forming an upstand, sheat hing felt is fixed to
asphalt and the metal trim.
sheathing felt extends up t o the edge of the
the substrate, often a separate upstand fixed
Penetrations through an asphalt covered
to the roof, as mentioned earlier. Expanded
roof are formed by extendingthe asphalt
metal lathing, typically at 150mm centres,
up by ISOmm to create a collar round the
primed in bitumen, is fixed to the face of
material. The top of the asphalt collar has an
the sheathing layer, which provides a 'key'
apron flashing around it to protect the top
to which the asphalt will bond. W here the
of the asphalt. An altemative method of seal-
upstand is formed in lightweight concrete
ing a roof penetration is to form a complete
block, the surface is faced with either a sand
upstand around the penetration which can
cement render, or metal laths and sheathing
be insulated to the top of the opening. An
felt is used as described.
insulated metal panel can then be mechani-
rainwater outlet.
MCH
25 7
Roofs
03- - - - - - - - - - - - - - - - - -
Timber roofs I: fl at roofs: mast ic asp ha lt coverings
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® System design This section discusses flat t imber roofs
® 3-D view showi ng ridge in mastic roof
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MCH
258
applied to concrete decks are usually laid in hot liquid form and are reinfo rced to suit the
that use the common combination of bitu-
specific condit ions of fold s and joints occur-
men sheet -based membrane as a w at er-
ring within th e struct ural deck In this section
proofing layer in a warm ro of. Alt hough
t he mat erial is considered as an exposed
oth er membrane mat erials are used on
and visible material o n a relatively lightweight
flat t imber roofs as bot h w arm and cold
deck
roofs , ty pically formed in elastomeric and
Bit umen sheet membranes are eco-
t hermo plastic memb ranes, th eir applica-
nom ic, and are often used w ith t imber ro of
tion is discussed in the earlier sectio n on
decks, w hich t ogether provide an economic
expose d membrane s in concrete roo fs. The
roof design for relatively small-scale applica-
princip les of detailing in that section can be
t ions, or designs wit h a comple x geometry
similarly applied to timber roofs. Bit umen-
of low pitched roofs, as is often used in
based sheet can also be used in 'inverte d
hou sing and in schoo l buildings. Bitumen-
roof, or concealed membrane configuration
based membrane s have develop ed over the
as described in th at earlier section w here
past 25 years t o compete with the newer
the detailing is similar, but bitumen-based
elastom eric and thermoplastic materials by
sheet is generally less ro bust th an the mem -
increasing t heir flexibility and making t hem
branes described in that section . Memb ranes
th inner, requiring less materi al, w hich helps
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Section I:IO. Roof light junction
Details
to reducetheir overall cost. Bitumen-based
greater dimensional stability and resistance
membranes can also be used with concrete
to accidental damage, as well as a polyester
and metal decks, and the principles here can
reinforced core to increasetensile strength.
3. Separat ing layer
be applied in a similar way to those roof
These sheet materials are typically around
4. Rigid thermal insulat ion
decktypes.
4mm thick, depending on the proprietary
Bitumen-based sheet is manufactured
system used. Even with theseadditives,
I. Mastic Asphalt 2. Plywood sheet or timber boards
S. Freestanding timber upstand 6. Vapour barrier 7. Softwood joists
in roll form in widths of around IOOOmm, is
bitumen-based sheet is slowly oxidised by
8. Drylining/drywall intemal finish
blackin colour, and is typically mixed with
heat, makingthe material gradually more
9. Metal flashing
SBS (styrene-butadiene-styrene) polymers
brittle which eventually results in cracks. The
10. Fascia
or with TPO (thermoplastic polyolefin) poly-
polymer additives reduce this effect, particu-
mers. The addition of these polymers raises
larly the TPO additives that help to increase
the melting point which ensures stability in
the life of the material, which can now be up
hot weather as well as increasing the flex-
to around 25 years. TPO-modified sheetcan
ibility of the material at low temperatures
be exposedto the effects of the sun, requir-
(usually in wint er in temperate climates)
ing no additional solar protection, since t he
and enhancing the fire resistance of the
material provides better UV resistance than
material. Bitumen-based sheetoften hasa
older-type bitumen-based membranes. SBS-
glass fibre reinforced upper face to provide
modified sheet is usually covered with stone
I I. Extemal Wall 12. Expanded metal lathing 13. Rain water outlet! other penetrations
MCH
259
...----Roofs 03- - - - - - - - - - - - - - - - ---, Timber roofs I: fl at roofs: mastic asphalt coverings
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chippings or solar reflective paint to protect
brane and thermal insulat ion to release gases
them from the effects of the sun.
into the isolating layer which are formed as a
typically by either t orching, bonding or
result of bonding the bitumen t o the insula-
mechanical fixing methods. Wi th t orching. a
System details Where plywood is used to form the structural deck of a timber roof, the joints between plywood boards are usually taped
Bitumen-based membranesare fixed
tion. The bitumen-based membrane isthen
flame is used t o melt an adhesive layer on
bonded to the thermal insulation thro ugh the
the underside of the sheet so that the mem-
holes in the isolating layer.
brane adheresto the substrate. Sheets are
Resistance to UV radiation is provided by
lapped by around IOOmm to ensure a water
to provide a continuously smooth surface.
either a coating of fine stone chippings or by
tight seal. Torches are usually gas fuelled,
On t imber boarded decks, where this is not
aluminium solar reflective paint applied to the
supplied from a small canister as part of a
as practical a method, a thin layer of bit u-
visible surface of the bitumen-based sheet.
hand-held tool , or are supplied from a large
men is laid onto the deck, applied typically in
As a result of providing this additional UV
gas cylinder set onto the roof to a variety of
thick liquid form t o seal the joints between
protection, these coat ings have the additional
to ols, either hand-held or wheeled, for larger
the boards, the bitumen setti ng to form a
benefit of reflecting heat, which has the effect
scale applications.
smooth substrate. A vapour barrier is set
of reducing the surface t emperature of the
ont o the prepared timber deck, the bar-
roof below that which would otherwise be
formed by either fixing the sheet to the ply-
rier being often bitumen-based as part of a
the case. Solar reflective paint givesthe roof
woo d face of a t imber framed upstand, or to the face of the thermal insulation, depending
Upstands in bitumen-based sheets are
proprietary system. Rigid closed cell insula-
a metal appearance, which provides a visual
tion such as polyurethane is bedded in hot
altemative t o the characteristic black colour
on the configuratio n of the extemal wall.
bitumen onto the vapour barrier t o hold the
of bitumen-based sheet. Membranes can also
Where a timber roof deck meets a masonry
insulation securely in place. A loose laid per-
be provided with a solar protection layer
wall, with the concrete block wall being clad
forated isolating layer is set onto the thermal
during manufacture as part of a proprietary
in timber rainscreen panels, the bitumen-
insulation which is used t o allow the mem-
bitumen-based membrane system.
based sheet is shown fixed to the face of
MCH
260
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Section I: IO. Eaves
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Section I:IO. Expansion joint
the upst and. With a low upstand, t he membrane contin ues up t he full height and exte nds across t he t op of th e wall underneat h t he coping. Th e roo f membrane is
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made conti nuous wit h th e waterproof seal of t he extemal wall, with th e membrane
3-D detail of expansion joint in mastic roof
tenrninating againstthe bitumen paint finish of the extemal face of the blockwork wall. Th e coping can be made from any impervious and durable materia l. A pressed metal coping, overhanging on both sides, provides additional protection t o t he membrane as it folds over t he top of the wa ll.
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Section I:IO. Balustrade
Section I: IO. Eaves
MCH
26 1
Roofs 03 Timbe r roofs 3: pitched roof: tiles
///
Section I:20. Unventilated roof
3-D view of ventilated roof with terracotta tiles
Section I:20. Ventilated roof
System design Clay t iles for roofs are most commonly made from clay or concrete . In t he clay t ype natural clay is mixed w it h additives such as
be used for pitches as low as 12.so above
escape, wh ich avo ids damage to both th e
t he horizontal.
t imber and the thermal insulation. In recent
Both t ile types are fixed t o timber bat-
years it has becom e more comm on t o use a
quartz, mica, iron oxide and crystalline alu-
ten s set horizontally, t hat is, at right angles to
vapo ur perm eable membrane or 'breather'
minium oxi de. Clay tile s are fired in a kiln at
the directi on of t he slope. T he batt ens are
membrane as t he underlayer t o t he t il-
aro und I 100°c to make th e material bot h
fixed onto roofing felt, wh ich form s a second
ing instead of waterproof roofi ng felt. T his
rigid and resistant t o moist ure penet ration.
line of defence and full weat hertight barrier
is done t o avoid vent ilati ng t he roof vo id,
Plain ti les are used o n pit ched roofs ranging
to th e roof T he roofing felt is set on timber
which can become very damp in temperate
from vert ical t ile hanging t o pitches as low
rafters (sloping timbers) or full t imber truss-
climates during w int er.
as around 35° above the horizontal. Inter-
es. T he ti les pro vide t he first line of defence
In the warm roo f, the sloping rafters
locking t iles, wit h groo ves and complex laps
against rainwate r penetration as w ell as
are filled w it h t hermal insulati o n in o rder
can be used in down to a minimum pitch
protecting the ro ofing felt from direct wi nd-
to allow the int em al space of the roof void
of 22.5° above t he horizontal. Conc rete
blown rain, the effects of the sun, as w ell as
to be used. A s with the cold roof, a vapour
tile s are made from aggregate and Port land
protecting the felt from accidental damage.
barrier is set between t he thermal insulat io n
cement w hich are mixed t ogether and t hen
Many t ile shapes and profile s are available
and t he int em al dry w all lining. A vapo ur
cured in te mperatu re-controlled chambers
w hich have been developed from histo rical
permeable mem brane is set on t he outside
in t he factory. Th eir appearance t ends to
examples. Th e design life for t iled roofs in
face of the slo ping rafters as an underlay to
imit ate t hose of tra ditional clay t iles in both
both clay and concret e types is aroun d 30
the til ing. If the insulation com plete ly fills t he
shape and variety of colour, but large inter-
years but th ey are actually expected to last
void between t he rafters, th en th is breather
locking tiles are available in sizes th at are
for around I00 years.
difficult t o achieve in clay. In commo n wit h
Like fiat roofs, pit ched roofs are formed
memb rane serves t o allow moisture t rapped w ithin th e construction to escape. If th e
clay ti les, concrete plain t iles are used in roof
as eit her warm roofs or cold roofs. In the
th erm al insulat ion does not fill th e void, and
pit ches down to 35° above th e horizontal.
cold roof, horizont al jo ints are insulated,
is set againstthe intemal dry lining, t hen th e
A n advantage of concrete ti les over clay t iles
and th e vo id is vent ilat ed t o ensure that any
vo id bet w een t he insulat ion and the breather
is t hat some concrete int erlocking ti les can
condensation forming in t he roo f void can
memb rane is vent ilat ed at t he ridge and at
MC H
262
3-D view of roof juntion with shingle clad wall
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3-D view of timber shingles on timber roof construction
3-D view of ventilated roof with timber shingle cladding
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Details I. Roof tiles, slates or shingles (tiles shown) 2. Softwood battens 3. Roofing felt 4. Gutter 5. Softwood rafter 6. Ventilation void 7. Themral insulation 8. Vapour barrier 9. Softwood joist 10. Dry lining/drywall intemal finish I I. Soffit board to conceal rafters but allow ventilation to air gap behind 12. Fascia board 13. Supporting wall (brick cavity wall shown) 14. Ridge capping (ridge tile shown) 15. Metal flash ing 16. Standing seam sheet
Section I:20. Eaves detail
The Lighthouse, Wat ford, UK, Architect: Shepherd Robson Architects
MCH
263
Roofs 03 Timber roofs 3: pitched roof: tiles
Phot ovolta ic or solar t iles being applied to t imber roof
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MC H
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Section I :20. Valley det ails for ventilated and unvent ilated roo f
down the tiles as well as any moisture nun-
used, th e cavity betw een the outside face
ning down the underlay, into the gutter. A
of the memb rane and the tile s is increased
vent ilat or, ty pically in PVC-U, is set betw een
from 2Smm t o SOmm w it h counter battens
the bottom t ile t o ventilat e eit her t he roof
to allow the air w ithin the void to mo ve
void in a cold roof, or the cavit y between
more freely, ensuring that vapour being
the underlayer and the tiles in a warm roo f
released t o th e o utside can be dispersed
configurat ion.
easily.
In the cold roof version t he pro prietary vent ilat o r is set beneath t he underlayer.
CD @
System detai ls Both plain ti les and int erlo cking t iles are
Fresh air is allowed to flow into the vent ilator set beneath t he bottom ti le and is
t ermin ated at t heir base w it h a gutter. In
released into the ro of void w it hout affecting
o rder to maintain a constant pitch of t iles
the the rmal insulation of the roof at ceiling
down to th e gutter, the bottom row of bat-
level, w hich is continuous between w all and
t ens is raised up on a w edge-shaped timber
roof. In the warm roof version, a ventila-
profil e called a t ilt ing fillet. This allows the
tor set between t he bottom t ile and th e
underlay t o meet t he underside of the bot -
felt underlay introduces air into th e void
tom t ile, and drain both rainwat er nunning
between the til e and the breather mem-
't
Section I:20. Eaves detail of slate tile
Section I:20. Ridge detail. Metal tiles on timber roof
@ 3-D section thro ugh standingseam roof on timber structure
brane. T he t herm al insulat ion either contin-
the batte n cavity between the underlay and
ues to t he fascia bo ard, th en ret um s hori-
the t iles, in a warm roof, or th e ro of vo id in
zo ntally back form a continuity w ith t he wall
a cold roof configurat ion. W here the batte n
insulation, o r altemativ ely the wa ll insulation
cavity is vent ilate d the cavity is sealed across
continue s vert ically until it reaches the slop-
the ridge. A ir is allowed t o pass through a
ing insulat io n set between th e rafters. In th e
gap betwe en th e bottom of th e ridge t ile
second versio n, the void forming the fascia
and th e roof t ile immediat ely beneath, the
and soffrt immed iately beneath it is in 'cold'
gap being fo rmed by the PVC-U vent ilat or.
roof configuration and is requi red to be ven-
Where t he com plete roof void is vent ed t o
t ilat ed in order to avo id damp, stagnant air
the outside in a cold roof, a gap of arou nd
from damaging t he t imbe rs.
IOmm in th e underlay is form ed at t he ridge.
Where a sealed ridge is required, ridge tiles are either bedded in a sand cement mortar, o r are dry fixed w it h metal screws, typically stainless steel, w here a rapid installation is required. For ventilat ed ridges, proprietary fixings usually made in PVC -U with vent ilat ion slot s are used to ventilat e eit her
MCH
265
Roo s 03 Plastic roofs I : GRP rooflights
3-D view of typical grp roo flight system details
~~~~~ic~ al .gutter/eaves detal
MCH
266
3-D views of typical ridge detal
3-D view s of typical edge detail
I. Translucent & insulate d GRP roo f panel 2. Thermally bro ken aluminium framing
3. Pressure plate 4. Supporti ng structure S. Folded metal cover strip 3-D overiew of GRP rooflight
6. Masonary/concrete wall 7. Gutter ARC, H ull, UK A rchitect: N iall Mclaughlin Arc hitects
System design Glass reinforced polyester (GRP) is used
set int o the void is usually bonded to the
sizes range from around 400mm x 800mm
in the form of thermally insulated panels to
outer GRP facing sheet s t o provide true
t o 800mm x 3000mm. GRP rooflight panels
form translucent roofiights which are robust
composite action between the GRP skin
use a lightweight framing system rather than
and economic when compared to an equiv-
andthe insulated core. Like metal compos-
a lapped junction or raised edges providing a
alent glazed roofiight with double glazed
ite panels, GRP panels increasingly have a
standing seam type joint used in metal com-
unit s. The advantages of GRP over glass are
thermal break introduced into the framing
posite panels. These maketheir appearance
its strength. lightness and flexibility, as well as
t o reduce the possibility of condensation
more refined. since the framing is very visible
the material's high resistance t o impact dam-
forming on the underside of the panel in
in translucent GRP panels. unlike their metal
age. GRP is a composit e material formed by
temperate climat es as well as to improve the
equivalent. An extruded aluminium T-section
reinforcing flexible fibreglass mat (or fibres)
overall thermal insulation value of the roof-
forms the support to the panels on all four
with thermosetti ng polyester resins that pro-
light Thermal breaks are usually made from
edges. with an extruded aluminium pressure
vide high tensile and compressive strengths.
an extruded polymer that has a much lower
plate being usedto hold the panels in place
The material is not combustible. making it a
thermal conductivity than aluminium, and are
on the outer face of the GRP panels. Most
suitable material for roofiights as well asan
bonded to the extrusion in the manner of
support frames are now int emally drained
opaque roof cladding material. Whi le GRP
glazed curtain walling or are clipped to it and
and vent ilated t o provide a second line of
roofiight systems do not usually achieve the
secured in place by self tapping screws that
defence against rainwater penetration. The
high levels of resistance to wind blown rain
hold the pressure plate in position.
outer seal is provided by an extruded EPDM
of intemally drained and ventilat ed curtain walling systems. they are robust and eco-
In small rooflights, up to around a 3000mm span, GRP composite panels
gasket clipped into the aluminium extrusion. Proprietary tapes are also used. but are
nomic, making them ideal where translucen-
require no additional support, while those of
more dependent upon good workmanship
cy is required rather than the transparency
great er span use an addit ional aluminium or
on site than gaskets which are fixed to the
provided by glass panels.
steel frame beneath t o support the compos-
pressure plat e in factory conditions.
Roofiights are made from GRP sheet
ite panels over the greater span. Panel sizes
Pressure plates for panel joints run-
which is bonded to an aluminium carrier
vary with the proprietary system and with
ning down the slope are set over the joint
frame around its edges. Thermal insulation
the individual roofiight design. Typical panel
between the panels in the manner of glazed
MC H
267
Roo s 03 Plastic roofs I: GRP rooflights Detail s I . T ranslucent & insulated GRP roof panel 2. T hermally broken aluminium framing
3.
Pressure plate
4. Supporting structure 5. Folded metal cover strip
CD
6. Masonary/concret e w all
ARC, Hul l. UK. A rchitect: Ni all Mclaughlin Arc hitects
3-D views of t ypical mo nopitch ridge det als
curtain walling. Joints running across the
an intermediary aluminium extrusion or
slope sometimes have pressure plates wit h
folded sheet is used to form the junction.
lapped joints, in order to avoid water build-
An outer EPDM or extruded silicone seal
ing up on the upper side of the joint and
is used asan outer line of defence against
being unable t o run over the joint. The lap
rainwat er penetration at the junction with
is formed by setting an aluminium strip or
the GRP roof panel. Drainage slots formed
extrusion, under the botto m edge of the
in the bottom of the aluminium closer piece
panel which laps over the to p of the panel
drain away any water that passes through
below. In addition to these standard junc-
the outer seal. These drainage slotsalso take
tions which form part of proprietary systems,
away any water to the outside from the
panels are joint ed with folded metal sheet.
drainage channels within the joints between
where unusual junctions are t o be formed.
panels that run down the slope of the roof.
An inner metal sheet is bonded to the junc-
The GRP panel beneath the closer piece
tion of the panels to provide an inner seal
that forms a vertical part of the rooflight
and vapour banrier.
is formed by sett ing the panel behind a vertical aluminium strip that forms a lapped joint over the top of the panel, avoiding the
Syste m details When a rooflight terminates in an eaves,
MCH
268
possibility of rainwater passing through the joint. The gap between the aluminium closer
3-D overview of GRP roofiight shell structure
3-D overview of GRP rooflight shell structure
ARC, Hull, UK. Architect: Niall Mclaughlin Architects
and the GRP panel is sealed with either an
aluminium sheet or angle closing the gap
EPDM gasket, a proprietary tape, or a sili-
between the panels. As with other panel
cone sealant. A metal gutter is fixed to the
to panel junctions, a waterproof membrane
metal closer if required, but this is usually
is set on the underside of the outer metal
exposed unless it fonrns part of a fascia, such
flashing as a second line of defence against
as the curved eaves used in profiled metal
rainwater penetration. The void between
roofing, for example. In smaller rooflights
t he panels is filled wit h mineral fibre quilt
the rainwater typically runs off onto the sur-
type thenrnal insulation, which has the flex-
rounding area of the flat roof.
ibility required to fill the inregular-shaped
The gable ends of sloping GRP rooflights
voids between GRP panels. An additional
are fonrned with an aluminium flashing that
aluminium angle is used at the junction of
is bonded, or mechanically fixed and sealed,
the inner face of the panels to provide an
to the metal edgeframe t o the side of the
additional seal and vapour barrier.
3-D detail of junction with extemal wall
GRP panel fonrning the sloping panel, and to the top of the t riangular-shaped vertical end panel. The sloping panel extends slightly forward of the vertical panels to give a thin edge to the roof, but altematively the roof can tenrninate in a sharp edge, with a folded
3-D detail of ridge
MCH
269
Roofs 03 Plastic roofs 2: GRP panels and shells Det ails I. 2. 3. 4. 5.
GRP shell panel GRP oute r cladding panel GRP structural rib GRP th in panel with honeycomb core Mild steel or aluminium frame
Section I:5. Panel to panel junction
=,~
Vertical section I: IO. Perimeter
Vertical section I : IO. Panel to panel junction
Verti cal section I :5. Panel to panel junction
CD
ZZZZZ;ZZ2222121Z
3-D section through GRP roof panels
Syste m design from a single segmented panel type to form
a spray directly into the mould. The mixture
rooflights, discussed in the previous section
a complete rooflight. Mouldsare usually
is applied t o a thickness of 3mm to
on rooflights, are made as panels which are
made from plywood to createthe shape
depending on the panel size required.
joined t o form translucent rooflights, opaque
and are then finished in GRP to create the
GRP panels can be made as monolithic, self-
negative shape of the panel being formed,
supported by a light metal frame beneath.
supporting shells, usually made from panel
GRP panels are fabricated by first applying
The frame comprises steel or aluminium
segments which are brought t o sit e and
a release agent to the mould to allow the
T-sections which are welded together to
Wh ile glass reinforced polyester (GRP)
~m
In the example shown, GRP panels are
bolted t ogether. The segment sizes of GRP
finished panel to be removed easily, then
form a structure that supports the complete
shellsare made in sizes which are suitable
thermosetting polyester resins are applied
outer skin. The frame has curved members
for transportation by road, usually set upright
to the face of the mould, with flexible fibre-
that radiate from the centre at the top to
on a trailer. The shells can then be lifted by
glass mat being laid into the resin, usually
the edge and from the centre at t he lowest
crane into place as a completed assembly,
with rollers. The process of fabricating GRP
point of the structure, backto the perimeter.
which makes them quite different from roof
panels is very labour intensive, but requires
The radiating 'spokes' of the wheel are held
structures in other materials.
no expensive equipment, making panel pro-
in place by T-sections that, in plan, form
duction a craft-based technique rather than
concentric circles. This 'bicycle wheel' form is
an industrial process. When the panels are
supported near its perimeter by a metal ring
The example shown is of a small shell for a rooflight. The shell consists of a set of segmented panels which are bolted together
released from the mould they are trimmed
beam that is set immediately above the glaz-
to form a roof shell of approximately 7.0
along their edges and ground smooth where
ing beneath the GRP roof. The ring beam is
metres diameter, supported by an additional
necessary. An altemative method is to apply
supported by posts that are fixed to the roof
frame. Panels are made in a mould, usually
a mixture of resin and glass fibre particles as
deck beneath.
MCH
270
Bus Station . Hoofddorp. The Netherlands. Architect: N IO architecten
=
-
- - -':-.;. ---
--~ 3-D detail of roof perimeter
CD CD
Plan and section I :SO. Generic example of roof geometry
CD
3-D view of underside of roo f
3-D section through roof assembly
MCH
27 1
Roofs 03 Plastic roofs 2: GRP panels and shells
3-D overview of GRP shell
Detai ls I. 2.
GRP shell panel GRP outer cladding panel 3. GRP structural rib 4. GRP thin panel wit h honeycomb core 5. Mild steel or aluminium frame 6. Mild steel or aluminium truss 7. GRP fiashing 8. W aterproofing membrane 9. Metal fixing bracket 10. Thermal insulation
3-D section t hrough GRP shell show ing intem al structure
Bus Statio n, Hoofddorp, The Nethe rlands. Architect: N IO archit ecten
MCH
272
Vertical section I: 10, Junction at base
,-
/
r
Horizontal section I: IO. Panel to panel junction
Vertical section I:IO. Panel to panel junction Verticalsection I:IO. Panel to panel junction
3-D detail of GRP panel connetion
3-D detail of GRP panel connetion to supporting aluminium frame
System details The metal frame is clad in prefabricated
Finally, a paint finish is applied, usually asa
transit ion from one side of the shell t o the
GRP panels which are bolted to the sup-
spray, to give a smooth and reflective fin-
other. In the example shown, a shadow
port frame on their int emal face in order to
ish. W here pigments are applied to the to p
groove is set around the joint between the
avoid visible fixings. Panels are made with an
coat, or 'gel' coat, in the factory, a more
central panel and the segments in order to
outer skin of GRP around Smm thick, with
limited range of colours is available. Thenrnal
avoid any misalignment between segmented
an overall panel depth of around 4Smm for
insulation is set on the underside of the
panels from being visible. The perimeter
the panels sizes shown of 3S00mm long and
shell, being bonded to the inner face of the
joint of the panel can be filled and sealed
1800mm wide. The GRP panels are stiffened
GRP panels in order to achieve continuity of
usingthe method described earlier, with
by concentric ribs, around 120mm wide,
insulation.
additio nal grinding required on site t o ensure
but ribs on the edges are thin in order to
Alt ematively, the glass fibre ribs that
facilitate their bolting t ogether. Panels are
fonrn part of the shell to provide integral
secured with bolts which are fixed through
structural stability to the shell could be
underside, has the same panels with the
the metal support frame int o reinforcing
made around 200mm deep to avoid the
same finish, but without any thenrnal insula-
ribs at the edges of the GRP panels. Joints
need for an additional steel frame. Panels
tion, which is typically set around the outer
a smooth finish. The intemal part of the shell, on its
between GRP panels are fonrned by butting
would be bolted together to fonrn a self-
edge of the shell in order t o keep tempera-
panels up to one another and sealing the
supporting GRP shell. Ribs would be made
tures within the void closeto those within
gap between the panels. The seal is fonrned
in solid GRP in order to allow them to be
the building. Close to the edge of the shell,
in a continuous step profile on the long
bolt ed together easily. Panels are joined and
on the underside, the joint betw een the top
edges of each panel that creat es a continu-
sealed on their extemal face in the same
panel, which curves around the edges, and
ous groove at the joint between panels. The
way as the example shown. W here panel
the adjacent panel undemeath, has a groove
groove is filled with a laminat ion of glass
segment s converge at the top of the shell,
fonrned along the joint to serve as a drip.
fibre and resin to fill the groove to the level
a separate centre panel is used to create a
Wi ndblown rain will still be pushed along
of the top of the panels. The extemal face
smooth extemal finish. A central extemal
the underside of the soffrt panel, but the
of the GRP is then ground smooth, usually
panel avoids the difficulty of bringing up to
drip reduces the amount of water that runs
by a hand-held grinder, to achieve a unifonrn,
16 panels together at a single point which
down to the glazing below.
smooth surface that conceals the joint lines.
would make it difficult to achieve a smooth
MCH
273
Roofs 03 Fabric systems I: ETFE cushions
3-D view of joint between ETFE cushions showing air supply pipes
o 0
Vertical section I:20. Connection between ETFE cushions
o1
I
CD
System design t ions, air-filled cushions remain in place when
manner of glazed rooflights, The clamping
the advantage of being light in weight, strong
the air supply fails or is switched off when
frames are then supported by a mild steel
in tension and durable, and have the abil-
used as non-Ioadbearing panels. Thistype,
structure formed typically as box sections or
Fabrics used as roof membranes have
ity to be cut to different shapesand joined
where ETFE sheet is used to make panels
tubes. Cushionstypically have three layers
together economically, which is difficult
formed as air-filled 'cushions', provide highly
that form two chambers. The two chambers
t o achieve so easily wit h metal and is very
transparent, lightweight and resil ient roofs
are linked by a hole formed in the middle
expensive to achieve with curved glass. Roof
that have thermal insulation values similar to
(flat) membrane in order to allow air to pass
membrane fabrics are used in tension struc-
those of double glazed units. The complete
to both chambers from a single air supply,
tures, either by stretching the material, or
ETFE cushion assembly is supported by a
and to ensurethat the air pressure in both
'prestressing' the membrane, between struc-
structural frame beneath, wit h mild steel, alu-
chambers remains equal. This three layer
tural supports or, altematively, by supporting
minium and laminat ed timber all being used
cushion provides a U-value of around 2.0
the material pneumatically in inflated struc-
to suit the design.
W/m2K, which is similar t o a double glazed
tures. The use of fabric membranes in pre-
ETFE cushions usually consist of a mini-
unit used in glass roofs.
stressed roofs is discussed in the next two
mum of two layers of ETFE sheet which are
sections on single layer fabric membranes.
set back t o backto form a flat panel and
This section considers ETFE cushions, also
are sealed at the edges. The void within the
called 'pillows' or 'foils', which are the most
cushion-shaped panel is inflated with air to
pipes or flexible plastic pipesthat are con-
common applicatio n of inflatable fabric roofs.
a pressure that varies with cushion size and
nected to the underside of the cushion near
the manufacturer's proprietary system, to
the clamping assembly. Pipes are usually of
provide structural stability t o the panel. The
around 25mm diameter, and are connected
ticularly for covering sports stadiums, they
increased air pressure stret ches, or 'pre-
t o a larger pipe that suppliesthe air t o all
remain structurally stable only while air is
stresses', t he outer membranes, giving ETFE
the cushions either side of a single structural
being supplied to the structure. If the air
cushions their characteristic curved shape.
support. This main pipe is also usually made
supply is interrupted, the complete roof
The cushions are held in place by clamps
from plastic and can be concealed within
structure deflates. In smaller scale applica-
that form a frame around the cushions in the
the supporting structure, being only up to
Although large scale self-supporting inflatable roof structures are in use, par-
MCH
274
System details Air is supplied to cushions from rubber
Kingsdale school London, UK. A rchit ect De Rijke Marsh Morgan
Details I. ETFE Cushion 2. Extruded aluminium clamping plate
3. Extruded aluminium retaining profile 4. Plastic edge bead to ET FE membrane 5. Supporting structu re 6. Plastic air supply t ube 7. Main air supply tube 8. Insulat ed metal lined gutter 9. Met al flashing 10. T herm al insulation 3-D overview of ET FE roof system
I I . Roof construction
MCH
275
' - - -Roo s 03- - - - - - - Fabric systems I: ETFE cushions
- - ...
r> U
-
-- CD
0
- - -- - 0
Vertical section I:I O, ETFE clamping detail
3-D detail of cushion to cushion air supply
(D@@
I
I
.1 :-.1
Vertical section I:I O, ETFE clamping detail wit h insulated gutter 3-D Overview of inregular shaped ETFE cushions used in facade assembly
a diameter of around 60mm. The air sup-
applied to the extemal face of the cushion,
ply, which maintains the air pressure within
the outer skin will deflect either inwards or
the cushions at a constant level, is supplied
outwards asa result of the positive or nega-
by electrically powered fans with air filters
tive pressures. This does not usually cause
(to avoid the passage of dust), as used in
damage to the cushions before the air sup-
mechanical ventilation systems within build-
ply is restored. Some manufacturers' systems
ings. The humidity level of the air is usually
have one-way valves to prevent loss of air
controlled to avoid the possibility of conden-
pressure from the cushions back to the sup-
sation fonrning within the cushions. Once the
ply pipes.
ETFE cushions have been inflat ed, air is sup-
Vertical section I:10. Junction at base
MCH
27 6
ETFE cushions are usually fabricated in
plied to the cushions for only around 5-10
the workshop but can be assembled on sit e
minutes per hour to compensate for loss of
to suit project conditions. The material is
air pressure caused by leaks from cushions
manufactured in rolls of considerable length
or from air supply pipes.
but of a width of around 1.5 metres. For
If air pressure within the cushion is lost
this reason, ETFE cushions are often made
as a result of damage to one of the outer
wit h spans in widths of around 3.0 metres
membranes or from loss of air pressure
t o 4.0 metres between clamped frames, in
in the supply pipe, the cushion deflates to
lengths up t o between 15 - 30 metres, but
it s flattened shape. As wind pressures are
lengths up t o 60 metres have been used.
Chanel travelling pavillion, Architect: Zaha Hadid
3-D detail of junction between ETFE facade and ground
Larger cushions are made by welding sheet to gether in the workshop t o form wider
complet e assembly usually performs in a
sheets for cushions that vary from the rec-
similar wayto the framing used for glazed
Details I. ETFE cushion 2. Extruded aluminium clamping plate
tangular form created from a standard width
roofs, with a drained and vent ilated inner
of ETFE sheet. Cushions up to around 7.0 x
chamber that serves as a second line of
7.0 metres have been made in a variety of
defence against rainwater penetration. Any
shapes from circles to hexagons using a hot
rainwater that passes through the outer
6. Plastic air supply tube
welded process undertaken in t he work-
clamping plate is drained away in grooves
7. Main air supply tube
shop. Larger cushions sometimes use a net
formed adjacent to the edges of the ETFE
of connected cables to provide additional
cushions, the water being drained back to
restraint.
the outside of the roof. The clamping assem-
The cushions have an edge bead, typi-
3. Extruded aluminium retaining profile 4. Plastic edge beadto ETFE membrane 5. Supporting structure
8. Insulated metal lined gutter 9. Metal flashing 10. Thermal insulation I I. Concrete slab
bly is typically around IOOmm wide, which
cally in plastic, which is used to retain the
is wider than that used for glazed roofs, but
panel in its supporting frame. The cushion is
less framing is required than that used on
set into a clamping frame, usually made from
glazed roofs .
extruded aluminium, that holds the panel in place by clipping it int o an aluminium profile, then holding it in placewit h an aluminium pressure plate that clamps the edges. The
MCH
277
Roo s 03 Fabric systems 2: single membrane: cone-shaped roof
Hampshire County Cricket Club pavillion. Southampton, UK.Architect Hopkins Architects
Tensile roof shape types: I. Cone 2. Saddle 3. Arch 4. Wave
System design design development, toge ther wit h t he t reat-
the low er po ints at the edges take up t he
fabric roofs are the ir smooth curves, t ypically
ment of int erfaces w it h adjacent areas of
effect of wi nd uplift. In shallow sloped roof
wit h different, in o pposite direct io ns, and
roof and extemal wall. T he resulting fo rm is
membranes, more of the structural loads
thin, sharp edges that pr ovide t ranslucent
designed to keep all parts of the fabric mem-
are t aken by t he edges or points at th e base,
T he advantages of single membrane
roofs th at allow diffused daylight t o pass
brane in t ension, not just fro m the support -
often result ing in large columns or posts
through t hem. Th ey use t heir curvatu re as a
ing structure but from imposed loads, mainly
being requ ired at th ese point s. T he distrib u-
method of t ensioning t he membrane against
w ind loads. W ind pressures are resisted by
t ion of loads w ithi n t he fabric roof design is
a supporting structu re, wh ich is ty pically a
re-distributing the fo rces w it hin the fabric
revealed in the suppo rt ing structure, w hich
mixture of mild steel tubes and stainless
mem brane. An y areas of t he fabric roof that
can be as visually lightweight and elegant as
steel cables.
go into compression as a result of slack-
t he fabric mem brane itself, or can become
ness in th e membrane reveal t hemselv es as
visually heavy, whic h can detract from the
In a fabric roof th e mem brane is structura
y mod elled so that th e resulta nt form
develop ed betw een archite ct and structural
creases in th e mat erial. Both the cone-shaped example in this
intended lightweight effect of th e membrane . W here roofs tran sfer fo rces to an adjoin -
engineer distribute s t he t ensile forces within
section and th e barrel -shaped example
ing struct ure, rather than conta in the loads
the membrane without over-tensioning
of the following sect ion make use of an
w ithin the ir own support ing frame, t he visual
some parts and under-ten sioning oth er
intemal steel structure t hat supports part
effect on the adjoining structure is balanced
parts of the membrane, with the result-
of the membrane, to t ensio n it in some
wit h the requ irements of the membrane
ing design resisting all load combinat ions in
areas, w it h roof edges wh ere the materia l
roof and it s own frame. As imposed loads
their different directions. T his w ork is usually
is held and tensioned , either at points or
such as snow or sand can cause permane nt
develop ed in th e form of a com pute r mod el,
w it h continuou s clamped fixings similar to
stretc hing of t he fabric membrane, t he form
eith er by specialist structural con sultants
thos e described in the previous section on
of the roof and its associat ed slopes are
or by manufacturers as part of th e design
ETFE cushion s. Generally speaking, th e high
made sufficiently steep t o avo id creat ing
development process. T he mini mal surface
po ints of t he suppo rt ing structure t ake up
areas or poc kets o n the fabric roof w here
form must also be suitable fo r draining away
the downl oads fro m the membrane and
t hey can collect.
rainwater, which forms another aspect of
imposed loads (m ainly w ind loads) and
MC H
27 8
Details I . Fabric membrane panel 2. Suppporting mild steel stnucture
3. Extnuded
aluminium clamp
4. Stainless steel cable 5. Membrane hood 6. Plastic edge bead to membrane panel
.
3-D detail of fabric membrane clamped to edge ring 3-D overview of cone shape roof w it h t ension cable suppo rt .
Vertica l section 1:5 Clamping ring w it h membrane skirt
(
3-D detail of edge ring supported by t ension cables
3-D det ail of cone top w ith protnuding stnuctural support
3-D detail of altemat ive pinnacle condit ion wit h membrane hood
MCH
279
Roo s 03 Fabric systems 2: single membrane: cone-shaped roof
Whitlingham ParkWater Activities Centre, Norwich, UK. Architect: Snell Associates
running the width. In most commonly used
System details The two most common fabrics used are
roof membranes, the tensile strengths of the warp and weft directions are similar, but
PVC-coated polyesterfabric and PTFE-coat-
these need t o be checked when the material
ed glass fibre fabric. Both are woven cloth
type is chosen.
materials which are protected by coatings,
Most fabric roof materials imitat e the
usually applied on both sides. Other open-
appearance of natural canvas, but this mate-
weave materials are used as solar shading
rial is used only where its appearance and
only, and are manufactured without protec-
individual texture is considered to be t he
Plashet school footbridge, London, UK.
tive coatings. These are made from poly-
most important feature. Natural canvas is
Architect: Birds Portchmouth Russum Architects
mer threads, sometimes with a protective
less stable than synthetic fabrics when used
coating applied to the manufactured thread
in tension structures, and is difficultto clean.
itself, to increasethe life expectancy of the
A modified acrylic canvas material, with a
material. In all these woven materials the
similar t exture to natural canvas, is some-
strength of the fabric can be different in the
times used for its greater dimensional stabil-
two directions in which the 'cloth' is woven.
ity. Neither material is suitable for long span
W hen selecting a material, the strength of
fabric roofs.
the' warp' threads running the length of the material is compared t o the 'weft' threads
MCH
280
Fabric roofs are highly susceptible to damage from sharp objects. Small cuts in
-0 I I
II
II
~=========-= JJ
Vertical section 1:5 Edge of roof at abutment
3-D cutaway detail of junction between 2 fabric panels
~LI~0 I
I:
II
I
II
II
II '---
~I...J
_________
Vertical section 1:5 Junction between panels
3-D exploded ~etail of clamp and membraneskirt
the membrane can be repaired with patches
cables attached to a steel bracket anchor
made from the same material which are
point on the top of the membrane roof. The
I. Fabric membrane panel
glued into pqsition , Larger tears are repaired
anchor point forms part of the steel or tim-
2. Suppporting mild steel structure
with hot air welders, usually undertaken by
ber supporting structureto the membrane
the specialist contractor that installed the
roof. Cleaning is also an important con-
5. Membrane hood
fabric roof. Large repairs are visible, and pan-
sideration in areas of high humidity where
6. Plastic edge bead to membrane panel
els are replaced where visibility isthe most
there is a higherrisk of mould forming on
7. Thenmal Insulation
important consideration. Since large tears
the surface of the fabric which can cause
can affectthe overall structural performance
permanent staining. Regular cleaning pre-
of the membrane, the complete membrane
vent s mould growth. PVC/polyester is more
is sometimes removed for another panel to
susceptible to mould growt h than PTFE/glass
be stitched or welded, and re-coated in the
fibre fabrics, essentially becausethe latter has
factory.
lower surface friction.
Details
3. Extruded aluminium clamp 4. Stainless steel cable
The outer surfaces of fabric roofs are cleaned with soft brushes that wash the membrane surface, the work being done typically from either a mobile platform or by rope access cleaners (abseilers) who are
3-D detail of junction between 2 fabric panels
attached in hamesses and suspended from
MCH
281
Roofs 03 Fabric systems 3: single membrane: barrel- shaped roof
National Tennis Centre. Roehampton. UK. Architect: Hopkins Architects
System design
width of the lap, which is visible from below
welding it to form a continuous pocket in
Roof membranes are made from individ-
the roof as well as from outside the building,
which a stainless steel cable is inserted. A
ual panels of fabric which are cut from sheet
is determined by the structural forces on the
2Smm diameter stainless steel cable is typi-
material. the curved forms of membranes
membrane. with higher loads requiring wider
cal. depending on the structural forces. A
being formed from flat sheet material. The
seams.
strip of membrane material or plastic is set
conical-shaped example shown here is made
Edges of membranes are usually either
between the cable and the membrane to
from panels with edges that curve inward.
gently curved or straight. Curved edges are
allow the two to move independently with-
while the barrel-shaped roof shown in the
formed with a cable held in a continuous
out abrasion occurring. A reinforced plastic
next section is made from panels wit h edges
pocket at the edges of the membrane. An
strip is sometimes added into the pocket but
that curve outward. PVC coated polyester
altemative detail used in PTFEIgiass fibre
this is not visible from either above or below
fabric is made in widths from 2000-3000mm,
canopies is to have an exposed cable con-
the roof. Straight clamped edges use clamp-
in thicknesses up to 1.2mm, while PTFE
nected to the clamped edges of the mem-
ing plates. around IOOmm wide. set back to
coated glass fibre fabric is made in widths
brane with a series of stainless steel link
back and bolted together. which comprise
up to around SOOOmm in thicknesses up to
plates. Straight edges are usually formed with
two flat, grooved plates, rather than the
I.Omm. Large panels are usually cut by CNC
an edge bead made from a flexible PVC or
clamping plate and supporting extrusion
cutting machines. with small pieces cut by
EPDM rod in a small pocket. This reinforced
used at joints between panels. W here two
hand. but even small pieces are now being
edge isthen held captive within an alumin-
cables meet at membrane comers or points.
made increasingly by a cutting machine.
ium clamping plat e assembly similar to that
they are usually fixed to a single mild steel
Fabric panels are usually made slightly
used for ETFE cushions. or altematively in a
plate. The cable is fixed int o a stainless steel
undersized t o allow for the stretching of the
luff groove extrusion.
material when it is under tension as a roof membrane. Fabric panels are joined t ogether with lapped seams which are either sewn,
cable fixing which is secured with a pin connection back t o a supporting steel plate. The
System details Cable restrained curved edges to fabric
comer of the membrane is cut to form a curved end. Additional straps are somet imes
welded, bonded or joined in a combination
roofs usually follow a circular or catenary
added to ensurethat the membrane does
of stitching and welding. with all processes
shape. A sleeve is formed by foldingthe
not slide away from the comer.
being carried out in the workshop. The
membrane backover itself and stitching or
MCH
2 82
Suspension points at the t op of a cone-
Details I. Fabric membrane panel 2. Suppporting mild steel stnucture
3. Extnuded aluminium clamp 4. Stainless steel cable 5. Membrane hood 6. Plastic edge bead to membrane panel 3-D cutaway detail of fabric roof edge
7. Thenmal Insulation 8. Perimeter wall build up 9. Fixing clip 10. Aluminium clamp assembly
Vertical section I: IO. junction of adjacent fabric membrane meeting at same angle
cb
cb
@
--
cp
~
cp
cb Vertical section I:10. junction of adjacent fabric membrane meeting at same angle
3-D detail of edge clamp
@
f
~
---:-: \
~
-
.-
--
CD
-
@
Buckingham Palace ticket office. London. UK Architect: Hopkins Architects
MCH
283
Roofs 03 Fabric systems 3: single mem bra ne : barrel-shap ed roof
...' . 4 ,'
/
/
.> - --
/
/
Millennium Dome, London, UK Architect: Richard Rogers
Details I. Fabric membrane 2. Edge seal clamped to continuous plate
3. Structural support 4. W all panel 5. Out er membrane 6. Liner membrane 7. Steel supporting structure 8. PTFE film or similar slip layer 9. Continuous stainless steelor aluminium bar 10. Pressed metal flashing
Vertical section I:10. Single skin system with steel edge support
Vertical section I: I O. Double skin system wit h steel edgesupport
MCH
284
;'
/'
,/
/
;'
Millennium Dome, London, UK Architect: Richard Rogers
shaped fabric roof are usually formed either
t ilevered bracket s w it h a curved shape are
membranes that form the valley, Th e edge
by a metal ring, which is fixed back to a cen-
set out radially in order to create a smooth
of each membran e is clamped with an edge
t ral mast by cables or cantilevered brackets
curved form o n whi ch th e membrane is set.
bead, wh ile the clamp itself is fixed t o a cen-
or, alternative ly, by a 'palm tree' anrange-
Th e brackets are usually aligned w it h joints
t ral cable, Th e gap between th e memb ranes
ment of projecting curved met al brackets
between memb rane panels.
is closed by two mem brane strips w hich
which serve t o t ension the continuous mem-
In an extem al fold in a roof membran e,
are sewn or welded t o t he base of the strip
brane against Iits supporting mast set wit hin
t he materia l is draped over the supporting
the building.
struct ure, fixed w ith fabric strips t hat are
plate between the mem branes, T he clamp
sew n or w elded t o t he underside of the
that closes the two mem brane strips is sup-
requires an additional membrane cover
membrane and clamped t o the suppo rti ng
ported off the meta l straps beneath. By rais-
piece, w hile the second 'palm tree' option
structure . A n addition al memb rane cover
ing t he closing strips above t he height of the
The first option with a meta l ring
and are clamped down to a th in pressure
forms a continuous membrane w it h a
strip is fixed to the top of the joint to con-
joint two adjacent gutters are formed, with
smoot h curved top, wit ho ut any breaks in
ceal the stitching if required. An alt em ativ e
the clamping strip securing the closing flaps
the continuity of the membrane. In the 'ring'
method is to form a joint between two
above the level of t he w at er being drained.
solut io n, the membrane is clamped betw een
membranes at the extemal fold, clamping
an inner ring and an outer ring fixed togeth -
them wit h a pressure plat e to an aluminium
er w it h bolts, A second clamp is used to
extrus ion which is supported by t he primary
fix t he cone-shaped membrane th at covers
structure, such as a mild steel tube, curved
th e t op of th e ring. The t op of th e conical-
t o form t he shape taken up by the mem -
shaped cover is either pulled over t he top of
brane, Intem al fold s are formed in th e same
th e central mast or clamped aro und it. Th e
way as ridges, wit h th e membrane folded
ring is either freely suspended from cables,
outwards rather t han across the ridge and
or is firml y fixed t o the mast with cantilev-
downwards. In some cases t he membrane
ered brackets to w hich th e ring is secured,
may pass under the cable, T hese junctio ns
In t he 'palm tree' suppo rted solut io n, can-
are formed by clamping the ends of adjacent
MC H
28 5
STRUCTURE Material systems for structures Braced frames I Reinforced concrete 2 Steel 3 Timber Portal frames Loadbearing boxes I Reinforced concrete 2 Brick 3 Glass Trusses Arches and shells Space grids Floor structures I. Cast in situ ICast-in-place concrete 2. Precast concrete 3. Steel and steel mesh 4. Timber 5. Glass Stairs I Concrete Steel 2 Timber 3 Glass 4
MCH
287
tructure 04 Mate,-ial systems fo r structures - - --,
Bracken House, London,UK.Architects: Michael Hopkins and Partners.
Bracken House, London. UK.Architects: Michael Hopkins and Part ners.
Structural stability
The roof. ifsufficiently rigid inthe horizontal
imposed loads.together with wind and snow
This chapter sets out the most com-
direction as in a reinforced concrete slab,can
loads and forces specifi c to use or location
mon/y used material systemsfor structures
also be considered to be horizontal bracing.
such as dynamic and seismic loads, can bring
together with the relationship between
Unbraced structures, in contrast,are allowed
about movements seen as bending and
structure and enclosure.Typical details
to sway as a result of their being unbraced
shear deformations which are a normal part
are shown for each material system and
in one direction.Their stability is provided by
of the building in use.An essential aspect of
their interface with walls and roofs. Struc-
rigid connections that provide stiffness within
structural movement inthe overall design of
tural 'types' inthis chapter are described
the structural elements. such as in portal
buildings is that its effects need to be taken
as systems based on the use of a primary
frames. Like braced structures. bracing in the
into account in the external envelope and its
material used to make a complete building
horizontal direction is provided by floors
interfaces. primarily at roof level.Tempera-
structure. Each example can be used as a
and. in the case of single storey structures.
ture changes, and differences intemperature
single structural system for a complete build-
by bracing in the plane of the roof.The most
between different parts of a structure. can
ing or,more commonly. be combined in a
common elements used to make building
cause expansion and contraction of struc-
mixed construction. Building structures are
structures are braced frames. portal frames.
tural members. with possibly some local
put into categories depending on whether
loadbearing boxes.trusses. arches and shells,
bending ofthose members.The detailing of
they are either 'braced' or'unbraced' in their
and space grids. Reinforced concrete and
both the components and any associated
construction. Braced types use devices such
masonry structures. despite their essentially
weatherproofi ng or internal finishes must
as internal walls or service shafts. or alterna-
monolithic nature. are considered to be
accommodate this movement without caus-
tively use cross bracing to stabilise the struc-
braced structures as some walls provide
ing damage to these fi nishes. Moisture pene-
ture .This vertical bracing is usually provided
specific bracing elements.
tration can cause expansion and contraction
intwo vertical planes at rightangles to one another in order to stabilise the structure both along its length and across its width.
in concrete, masonry and timber structures.
Structural movement The term 'structural movement' covers
Frost action, caused by the freeze/thaw cycle of moisture within structural materials. can
Horizontal bracing is provided by the floor
a wide range of effects of deformation and
eventually cause damage ifthe detailing is
structures which act as horizontal girders.
movement in building structures. Dead and
not sufficiently robust.
MCH
288
Saltwater Pavil ion, Neeltje[ans. Holland, Architects: OosterhuisAssociates.
Saltwater Pavilion, Neeltje [ans, Holland.Archit ects:Oosterhuis Associates. SaltwaterPavilion, Neeltje [ans, Holland. Architects: OosterhuisAssociates.
Saltwater Pavilion, Neeltje Jans, Holland. Architects:OosterhuisAssociates.
MCH
289
Reuters Building. London. UK, Architects: Richard Rogers Partnership,
Trends in the use of building structures Much effort in the design of building
Reuters Building. London.UK.Architects: Richard Rogers Partnership.
enclosure and internal finishes are co-ordi-
el applied, can now achieve a smooth finish
nated at an early stage of the design. con-
once associated only with the regular paint
tinuingthrough the following detailed design
finishes used in unprotected structures such
and construction phases.
as single-storey roof structures. Issues of
structures is focused on economy combined wit h safety. in term s of both the quantity of
thermal bridging in steel structures andthe In steel structures, frames have become
penetration of the waterproofing layer with
material used andthe amount of fabrica-
a full part of the language of architectural
steel components.are now easier to over-
tion neededto assemble t he structure.The
design. Assemblies in steel. ranging from
come with thermal breaks wit hin joints and
appropriat e use of structure can often be
small lattice tru sses to cable-stayed struc-
across weat herproofing membranes such as
seen in the 'fine tuning' of the balance of
turest hat resemble 'kits of parts'. have led
with the use of a set of bolted connections
material used and fabrication undertaken.
to their widespread use as highly visible
that are difficult to achieve in either concrete
This approach is being increasingly paral-
structures. set either outside or inside the
or timber.
leled in architectural design in the external
building enciosure.The necessity to join steel
envelope and int ernal fittings where there
sections wit h either welds or bolts has led
is a growing tendency to use the least
to a visual richness in both the design of
Concrete structures are now being exposed as self-finishes wit hin buildings,
number of components,while tempering
structural members and the joints between
both on the external walls and in the sof-
this approach wit h the needs of their fab-
them.This has been helped enormously
fit (underside) of structural slabs. with a
rication.This has led to an import ant trend
by the development of intumescent paints.
quality of finishtraditionally associated with
in structures of their increased visibility and
which protect the structure during a fire by
only plastered walls and ceilings. Exposed
asself-finished components within buildings.
expanding to form a heat-insulating layer
finishes in concret e are now less common
This brings the aims of structural design and
that protects the integrity of the structure
due to their poor weathering. from a visual
archit ectural design much closer to gether
for a limited period. usually one hour.These
point of view. but are enjoying a revival in
where the relationship between structure.
finishes. once only roughly textured or t row-
predominantly dry climates where thermal
MCH
290
Reuters Building, London, UK. Architects: Richard Rogers Partnership,
Jewish Museum, Berlin, Germany.Architects: Daniel Libeskind.
insulation is set within the depth of the wall.
structures as well as the use of these materi-
The renewed interest in precast concrete
als for concrete formwork , is set to trans-
led to the increased use of vapour barriers,
structural systems, other than those used for
form the geometries of structures built from
andthe careful placing of thermal insulation,
parking garages, is set to continue, with ever-
all these materials.The use of CAD/CAM
which need to be co-ordinated with the
greater expression of jointing forming part
permits much greater accuracy and closer
structural design in order to avoid interstitial
of the visible language of detailing.
tolerances in assembly with joints that are
condensation.The thermal mass of exposed
increasingly visually elegant. CAD /CAM is
concrete structures is being used for the
more complex both in terms of construc-
set to push further the drive towards pre-
night-time cooling of buildings in conjunc-
tion techniques and geometries used in their
fabrication.Timber and concrete, considered
tion with ventilated facades. The increased
design.The development of pinned jointing
traditionallyto be materials that are worked
prefabrication of both structures and facades
systems as well as the interest generated
on site, are now more frequently fabricated
has led to a greater awareness of issues of
in the material by its low levels of embod-
at the factory, for example in the pre-cutting
co-ordination at an early stage of the project
ied energyhave resulted in the revival of
of timber components and in the precast-
to ensure that highly visible finished compo-
Timber structures are becoming ever
building design in almostall c1imates.This has
exposed timber structures.The new genera-
ing of concrete components instead of their
nents,which in earlier buildings would have
tion of pinned joints helpsto overcome the
casting in situ.The building site will inevitably
been covered over by successive building
traditional problem of creating reliable and
become a place where assemblies are fixed
trades, can be successfully exposed as high
elegant joints that perform well in tension,
together rather than being the temporary
quality finished components.
particularly in large-scale glue-laminated
workshop to which we are accustomed.
structures. Thermal bridging, and the related effects The use of CAD/CAM techniques, or
of condensation, associated with the inte-
computer aided design/computer aided
gration of building structure with walls and
manufacturing, for both timber and steel
roofs,continues to be a significant issue in
MCH
291
I: reinforced concrete 3-D viewof concrete frame
Lyon-Satolas Station, Lyon,Architects: Santiago Calatrava
The use of precast and in-situ cast (castin
concrete combine easily with ground struc-
usually taken through the external walls and
place) concrete in frames provides a homo-
tures such as retaining walls and foundations
roof. requiring envelope details that allow
geneous structure where joints are made
because they are in the same materials and
for structural movement while remaining
as rigid connections.Theseframes require
can be continuous.
weatherproof.
Joints and Connections
Interface with external envelope
additional stiffness from bracing that can be provided typically by either concrete shear walls or steel cross bracing. Alternatively, lat-
Stiffness at the junctions of the frame is
Concrete frames can be either exposed
eral stability can be introduced into concrete
important both to provide sufficient rigidity
frames by stiffening other elements such as
in the frame itselfand to make its deflections
outsidethe weather line of the cladding, that
cores, shafts or stair enclosures.The inherent
compatible with the cladding and internal
is, the non-loadbearing walls, or be com-
fire resistance of concrete provides struc-
elements such asstaircases.This can be
pletely enclosed by the external envelope.
tures that require no further fire protection
achieved either within the joints forming the
When exposed externally, the penetra-
measures. With in situ castconstruction,
frame, by including extra reinforcement, or
tion of the frame through the walls and
the abilityto re-use formwork is important
by using additional stiffening walls such as
roof requires careful detailing to overcome
in keeping its useeconomic. Each 'lift' of
those used to enclose elevator (lift) shafts
weatherproofing andthermal bridging
concrete, typically a floor with its supporting
and service cores. Typically, deflections in
around penetrations of structural members
walls and columns, takes longer to construct
concrete beams or slabs are designed to be
through the cladding. Grooves are often cast
than an equivalent steelwork structure,since
compatible with the external cladding, parti-
around penetrating beams to allow fiashing
the concrete takes time to reach an ade-
tions and fittings within the building.
pieces to be inserted to assist in forming
quate strength to allow another floor to be
Movementjoints are introducedto allow
a weather seal. Cladding is fixed either by
built on top. Although the construction of an
for thermal movement.These junctionsare
a continuous stainless steel channel that is
in-situ castreinforced concrete frame is con-
effectively breaks in the structure,resulting in
cast into the edge of the concrete slab, or
sidered slower than erectinga steel frame,
the overall structural frame comprising a set
by expansion bolts secured into the slab
the construction times can be matched if the
of smaller linked frames, each an independ-
when the cladding is fixed. The bolts may
concrete work is well organised. Frames in
ent stable structure. Movementjoints are
also secure stainless steel angles, brackets or
MCH
292
Curved concrete frames .Scienc Park, Valencia,Spain, Architects: Calatrava
Organic concrete forms. Phaeno Centre ,Wolfsburg, Archit ects:Zaha Hadid Architects
Details I.Reinforced concrete wall 2. Concrete floor deck 3. Double glazed windows
3-D view of ooncrete frame
MCH
293
tructure OLi Braced frames I: reinforced concrete
_ - +-- -
3-D cut-aw ay view of concret e fr ame
3-D section view of concrete frame
MCH
294
-
-
r--- - - - -
3-D views of concret e frame
Exploded viewof concrete frame and panel system continuous rails depending on the nature of
mental strategy within the building to benefit
tion, with the introduction of CNC cut
the lightweight cladding. Reinforced concrete
from the thermal mass of concrete. In recent
polystyrene forms that are set into the form-
panels can be secured wit h additional metal
years, with the enhanced weathering char-
work to produce complex shapes in either
pins castinto the top surface of the concrete
acteristics of precast concrete,the thermal
precast or in-situ cast concrete.The ability of
slab.
insulation is set into the thickness of the
concrete to take up complex shapes using
wall, resulting in the construction being of
economic formwork has led to a gradual
integration of wall,roof, floors and columns
diaphragm type rather than a single wall with
move to more sculpted forms in concrete
into a single form of construction. Support-
a non-loadbearing skin set either internally
frames, as seen in the work of Zaha Hadid
ing walls and!floors can be integrated into
or externally. In the diaphragm wall.the two
and Santiago Calatrava.The visual continuity
shell forms a~ seen in the Science Park in
halves of the wall are linked by either stain-
of openings in walls, roofs and floors within
Valencia by Santiago Calatrava. Concerns
less steel ties or by reinforcing bars.
Reinforced concrete frames provide an
buildings gives a spatial continuity and fluidity
Regardless of whether concrete is
which can be achieved without the need for
have led to the material being covered by
formed in-situ or is precast,the material is
elaborate decoration - the frame provides
an additional weathering material, which
cast in formwork. In-site formwork istypi-
an elegant expression of form wit hout the
of the weathering capability of concrete
can be thin metal panels, or even an applied
cally made from plywood sheets but any
need for secondary finishes.The develop-
coating. Recent improvements in surface
material can be used.The material used for
ment of the reinforced concrete frame of
finishes, with honing and polishing used in
formwork leaves a strong impression on
columns and beams has seen considerable
precast concrete,have allowed a slow re-
the concrete finish, often with a high degree
elaboration in the work of Calatrava, follow-
introduction of concrete as an expressed fin-
of visible detail.This allows the concrete
ing visual principles of animal skeletons as
ish. An essential issue has been the thermal
frame to have a wide range of finishes from
well asdrawing visual inspiration from equiv-
bridging associated with concrete structures,
timber boards, leaving a high degree of vis-
alent steel structures. Reinforced concrete
which has led to thermal insulation being
ible texture on the surface, to very smooth
frames have shown the ability to move from
set externally with an additional weathering
concrete where plastic laminate coated
being simple, rectilinearflat forms to being
material on the outside.The positioning of
plywood is used. Digital fabrication has had
visually rich structures of complex geometry
the insulation externally allows the environ-
a modest influence over concrete construe-
of either curves or folds.
MCH
295
Structure 04 Braced frames 2: steel
Steel connecto r base plate det ail
Steel connection plate detail
Steel frames are made from columns and
painted components that can be assembled
set either on top of the steel beams of the
beams that are fabricated in factories and
on site and lifted into place by crane, avoid-
structural frame, or is set on a continuous
workshops and assembled together on site.
ing the need for substantial scaffolding. Care
steel plate welded to the bottom flange of
Unlike reinforced concrete frames, steel
is taken not to damage the surface finish, as
the steel beam.The advantage of the former
frames can be readily assembled with either
touching up of galvanizing and paintwork on
method is its simplicity of construction,while
rigid moment connections or wit h pin con-
sit e is slow, laborious and more difficult than
the advantage of the latter is in reducing the
nections. Lateral stability is provided typically
in the factory.
with either the cross bracing of some bays, or with staircase enclosures, cores or shafts.
overall depth of the structural floor zone, which can in turn reducethe overall height
Joints and Connections
of the building wit h attendant savings in the cost of the external walls. In addition,the use
Steel frames are usually shot blasted,
Joints in steel frames are bolted or
of a composite concrete and steel deck pro-
cleaned and primed prior to erection.
welded. Bolted connections are the most
vides essential properties of fire protection
Frames that are not to be left exposed visu-
commonly used, with either cleats or plates
and acoustic separation. Movement joints are
ally require no further painting. However.
used as connectors.The advantages of a fast
introduced to allow for thermal movement
most steel structures require fire protec-
speed of construction on site associated
in the steelwork,which can be greater than
tion, which is provided typically with either
with steel frames is often continued into the
that of concrete.Thesejoints are breaks in
concrete encasement, an intumescent paint
configurat ion of the floor slab,which often
the structure where each part of the struc-
or by enclosing the frame with fire resistant
uses trapezoidal shaped floor deck instead
tural frame must be independently stable of
board.Steel frames not requiring fire protec-
of full concret e slabs.The profiled metal deck
its neighbour.The corresponding movement
tion, such astho se used for roof structures
is used as both permanent formwork as
joint on the external wall and roof is detailed
only, are painted to avoid corrosion during
well as having a structural role in composite
so as to provide a continuity of waterproof-
construction and after the frames are assem-
action. Concrete is poured on top of the
ing while creating a break in the structural
bled. Members which are to remain visible
metal deck, which typically has shear studs
support of the external wall across the joint.
when assembled, such as in visible roof
or connector s to form a bond betw een the
Movement joints in the external wall are
two materials.The profiled metal deck is
typically up to around 20mm wide, so do
structures, are often delivered to site as preMCH
296
Braced st eel frame . Pompidou Centre, Paris, Arc hit ects: Richard Rogers
3-D view of section con nection detail w ith cross br acing element
I . I-section column 2. I-section beam
3. Floor deck 4. Cleats formed from steel angle 5.T-section or fiat section s com monly used for cross brac ing
MCH
297
ructure OLf Braced frames 2: steel
D etails I . I-sectio n co lumn 2. I-section beam 3. Floor deck 4. Cleats fo rme d fro m steel angle
I
5.T-section o r flat sections com mon ly used for cross br acing
Typical br aced frame con stru ction
not have a significant visual presence on th e
or 'pressed' sectio ns prov ides a mixture of
commonly.external walls are set on t he out-
facade, but are usually designed to make
material systems in a single materia l, using a
side of steel frames, as cladding fixed to t he
t hem an intenti onal part of th e language of
commo n meth od of fixing, w it h screws and
edge of th e concret e floor slab, so met imes
constructi on.
bo lts. Small frame s can benefit from the w ide
w it h an addit ional backing wa ll set onto th e
range of structural steel sections available,
edge of th e floor slab. Sometime s facades
two storey buildings have th e advantage of
fro m I-section s t o T-section s, box sections,
are suppo rted by brackets fixed to the outer
being able to be fabricat ed in th e workshop
tub es and flats, as we ll as specially fabri cat ed
face of the steel beam at t he edge of the
as a 'kit of parts' for complex fo rm s. Pro files
sections of irregular shape.The int roduction
frame, but th is can be difficult to achieve in
can be cut, curved, w elded and bolted in fac-
of irregular shapes has been possible as a
practice due t o th e co-ordinat ion needed
tory conditions for individual projects w here
result of the development of digital cutting
between steelwork and facade away fro m
the steel frame is visible form eit her inside
t oo ls.
sit e, w hich can be challenging from the po int
Interface with external envelope
construction.
Smaller scale steel frame s for one o r
of view of sequence of procurement and
or outside the building.This method allows welded joints wh ich can be groun d smooth and painted before being delivered to site in
In common w it h reinforced concrete
Roofs in different mat er ial systems are
sections, where th ey can be bolted in place,
frames, steel frames can be either exposed
set onto steel frames eit her direct ly.as in th e
achieving a level of w orkmanship t hat wo uld
outside th e ext ern al skin or be set inside t he
case of a profiled metal deck, or w it h support
be more difficult under site conditions. For
building, but w hen set externally. th e frame
brackets fixed to the steel framing members
short spanning, lightweight steel frames, cold
is ty pically th ermally insulat ed to reduce
in th e case of a glazed roo f.The use of brack-
formed sections can also be used, wit h thei r
thermal movement of t he frame. Ho wever
ets th at lift th e roo f system clear of th e stee l
advantage of being light er t o handle, forming
the connecti on, through t he ext ernal w all,
suppo rt ing memb ers give a sense of visual
frames w hich are more a steel equivalent
of the externall y-set columns and beams to
separat ion, w hich can assist visually in th e
of th e timber platform, w it h member s at
the floo r slab can be challenging.Th e need t o
relation ship between frame and covering.
close centres,th an looking like a regular steel
create a weat hertig ht seal around thi s junc-
frame.T he ability t o mix hot ro lled steels,
t ion requires special attent ion as t he seal is
capable of lo ng spans,w ith cold formed
usually formed w it hin a spandre l panel. More
MCH
298
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II
) ))))))))])))h~{«(<«((((((( ( Layout of steel work
Braced steel framed construction.Wood Street, London.Architects: Richard Rogers
Angled steel sections
I Beam connection detail
,l I
.......
....., .
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,
iil1.-Steel frame showingareas of bracing
3-D section through curved brace frame construction
Curved I beam connection detail
MCH
299
ru ure O~ Braced frames 3: timber
..
3-D cut away view of a typicaltimber frame
Typicaltimber joinery and connection details
The platform frame The platform frame consists of soft-
and external finishes. Prior to the use of plywood,timber boards were the main form
wood t imber studs, typically IOOmm x
of sheat hing for the frame. Floor spans are
50mm, spanning vertically from floor to
typically at up to around 3500mm to suit
floor between horizontally-set timber sec-
the ready availability of cut sections, but ply-
tions,cal led plates.The studs are set at close
wood-based floor joists can achieve longer
centres,typically at 400mm as described in
spans, depending on t he design. Openings
the section called 'Cladding to the platform
in walls, floors and roofs are easily formed
frame' in the Walls chapter. Floor joists are
and steel or engineered wood beams can
aligned wit h the studs to transfer the loads
be incorporated to increase floor spans.The
efficiently from floor to wall.Timbers are
walls to the platform frame are discussed in
butt jointed and nailed,following the tradi-
the Walls chapter; and timber floors are dis-
tion of using simple t echniques and relat ively
cussed later in this section.
few tools to make a complete structural frame from cut timber sections that can be lifted by hand.The stability of the frame
MC H
300
Long-span timber frames Larger frames can be made from either
is provided by plywood sheets, which also
laminatedtimber or large cut sections which
form a substrate for a breather membrane
are connected pairs, spaced apart,to make
,
3-D cut away view of a typicaltimber balloon frame on a masonry base
larger components.These frames consist of columns and beams at 5-6 metre centres with infill panels between them to make
Hardwood t imber frame There has been a revival in recent years in the UK for the use of timber frames that
walls. Floors are usually set on top of the
use large size sections of hardwood such as
beams.The large scale nature of the frame
oak,Douglas fir and larch to make frames
makes it necessary to introduce cross brac-
that use traditional methods of frame con-
ing or timber framed wall panelsto provide
struction rather than those of the platform
lateral stabilityThese large scaleframes are
frame.This method uses timber sections
increasingly being formed in cross laminated
from around 300 x 300mm down to small
timber; which have the ability to also be used
scale I OOmm x 50mm sections in a hier-
as fioor decks that have higher acoustic per-
archy of primary, secondary and tertiary
formance than timber joists and fioor boards.
members, allowing most of the timber con-
Although sand pugging and layers of ceiling
struction to be revealed rather than being
board can be added to the timber joist fioor;
concealed behind plywood sheathing and
their disadvantage has been to add mass
internal lining more typically associated with
without increasingthe strength of the fioor
timber construction. Spans are modest,typi-
construction.
cally achieving those of platform frames. MC H
30 I
Typical timber balloon frame on a masonry base
MCH
302
Typicaltimber joiner y and connection deta ils
3-D cut away view of a typicaltimber frame
Joints and Connections
being used to reduce the amount of fabrica-
fully visible within the building.A traditional
tion required and to provide a substantial
issue of infill panels has been to assure a
and smooth appearance.Timbers are fixed
weathertight joint between a timber frame
frames use knee bracing and wooden pegs
t ogether using a set of t ight-fit steel pins that
which undergoes structural movement, and
at joint s as an alternative to visible metal
are inserted into the connecting members.
an infill that is also subject to its own move-
connectors.The use of larger size sections
This type of connection is used at tension
ments.The use of breather membranes and
allows them to be cut to curves from single
joints.which are hard to achieve except by
rainscreen construction has greatly improved
pieces of t imber, or even to usetraditional
either bolting or by using split ring connec-
this traditional t echnique to meet modern
joints between large scale sections which
tors.
requirement s.The timber frame can also
W here platfo rm frames use primarily
nails to fix thel frame together. hardwood
interlock as a result of their shape rather than rely on straight metal connectors Long span t imber frames, connected in with timber blocks and bolted together.
be fully prot ected externally.typically with a
Interface with external envelope
breather membrane and rainscreen cladding,
The use of the platform frame suits
to control moisture movement in the frame,
continuously supported. or short-spanning,
as well as providing venti lat ion to the con-
often form simple bolted connections wit h
cladding materials such as timber boarding
struction where it meetsthe external wall.
timber columns by settingthe beams on the
and metal sheet. In the case of hardwood
As with other forms of timber construction.
outside of the column, or vice versa to suit
timber frames and long-span frames, the
timber frames are set onto masonry or con-
the structural design of the frame. However.
framing forms a primary part of the external
crete bases to keep them dry and ventilat ed.
this t echnique is being superseded by tight-fit
walls. providing an opportunit y to use infill-
typically set a minimum of ISOmm above
connections that use CA D/CAM t echniques
ing panels, such as double glazed unit s or
external ground level, but subject to specific
to direct computer-operated machinery that
low energy materials such as straw bale and
design requirements.The base wall follows
can plane, rout or drill structural timbers.
hemp. described in the Environment chapter.
the principles of that form of construction,
This new technique can provide economic
Roofs t o hardwood frames follow tradit ional
typically a cavity wall in the case of brickwork
connections that transfer loads more effi-
principles of keeping the structure dry wit hin
or a wat erproofed concrete wall with an
ciently than do traditional techniques. Solid
the building, with the roof coveringthe com-
additional outer skin t o protect and conceal
timber circular columns are increasingly
plete structure. but allowing the frame to be
the membrane.
MC H
303
Rigid reinforced concrete portal frame
An essential characteristic of the portal
portal frame can be applied to multiple sto-
frame isthat it supports loads by bending
rey frames,tho ugh they are typically used to
at its primary joints rather than using the
provide economic structures for long-span
pin joints of other frame types. However, in
single storey buildings with the benefit of
either welded or bolted with plates t o form
practice portal frames are made in sections
their comparatively low weight.
haunches. Some steel portal frames use
which are pin joint ed,t ypically at the top, in the centre and at their base.The frame
Portal frames are typically made from
Joints and connections Moment connections are typically
specially fabricat ed connectors int o which
steel, laminated timber and reinforced con-
standard size box sections can be slotted and
is made stable in the plane of the frame as
crete.As is the casewith arches, there are
welded. Larger scale connectors use cast-
a result of the rigid moment connection
three types: the rigid frame,the two -pin
ings for both moment and pinned connec-
between the column (or vert ical member)
frame and the three-pin frame. In the rigid
tions, giving a visual continuity to the design,
and the rafter (or horizontal member).
portal frame, the structure uses the least
though they are used primarily on larger
Structural members are formed typically
material, with the rigidity of the joints being
scale projects where benefits of making cast-
either as solid beams or framed trusses, and
t aken down as far as the base of the frame.
ings in high volume can be made economic.
resist bending at their knee joint to form the
The pinned types act in a similar way to
Pinned connections use types illustrated
moment connection by the use of rigid con-
arches but the loads in each member are
here. Smaller scale portal frames can be
nectors.These connectors might be glued
resisted in bending. Portal frames are linked
fixed together in a way t hat gives them the
joints in laminatedtimber, metal connectors
together with purlins to form linear arrange-
appearance of being single components, but
in framed timber members, or welds in steel
ments at around 3000mm to 6000mm cen-
which are bolted or glued together on site.
sections.An advantage of this structural type
tres. Since t he purlins alone do not usually
This can give the portal frame a more sculp-
is in its economic use of material, combined
provide sufficient rigidity in the transverse
tural appearance, with the structure resem-
with a simple construction technique.A
direction,the frames are stiffened with addi-
bling more boat construction than traditio nal
wide range of structural components can be
tional lateral bracing in a few of the bays,
building. The use of digital fabricatio n tools
used, from trusses and trussed columns to
usually near the ends of the structure, but
such as CNC router s brings the opportun ity
I-sections. Although associated primarily wit h
this depends on the scale of the structure
for portal frames to be made in different
single storey structures,the principle of the
and t he specific design.
sizes in order to form a more complex space
MCH
304
3 pintimber portal frame
Details I. Portal frame 2. Cladding
Vertical section I:100. 3 pintimber frame
------"'----
3 pintimber frame
\
1
\I
Ji 2 pintimber frame
ING Head office, Budapest, Hungary. Architects:Erick van Egeraat Associated Architects Rigid frame
MCH
305
trueture 04 Portal frames
Pin detailwithin timber portail frame
Base plate actying aspin joint for timber frame timber frame
en
Corner detailthnough rigid steel portalframe
Rigid steel fame corner detail
wit hin the building.The purlin members that connect the portal frames together are
HeathnowTenminal 5,London. Architects:Rogers Stirk Harbour
MCH
30 6
•
Interface w ith external envelope An advantage of portal frames is their
then cut at different angles on their ends in
ability to form a single surface for both walls
order to follow a particular line across the
and roof.In recent years,sheet metal roofs
structure,which may be visible from inside,
have been used with small scale portal frame
or be set in a staggered arrangement to suit
structures,wit h their ability to render the
the external roof and wall fi nishes. Portal
shape created by the structure. In other
frames are being increasingly associated with
examples the external skin is set between
non-rectilinear structures with their abilityto
the portal frame members, revealing the
form complex shapes with visually elegant
shape of the frame and makingthe struc-
connections. Large scale portal frames can
ture the visual expression of the design.The
provide a visually elegant and more slender
portal frames are weather protected and
alternat ive to classic trusses, creating roof
thermally insulated, often using the same
structures that more resemble shellsthan
metal sheet system, but wit h the opportunity
frames.A recent development isa hybrid of
for setting glazed units between the portal
portal frame structures which isthe use of
frames in line with the adjacent covering
a 'tree' like column arrangement of portal
for wall and roof. Purlins are used to sup-
frame connections at the top of a structure
port the external cladding.W here profiled
that support curved beams along its length.
metal cladding is used they are called sheet-
Rigid steel portal frame construction
Pin detail. Vertical section through glulam portal frame
ing rails. In common with arches, cladding
base of portal frames typically has an upstand
is fixed to these purlins rather than directly
to provide weat herproofing at this point
to the portals in order to keep the connec-
dependent on the position of the portal
tion type simple.The stiffness of junctions
frames, either at ground level or as part of a
between walls and roof makes the transition
larger structure.The upstand provides a ter-
in the external envelope straightforward
mination to the external envelope, forming
and economic. Largerscale portal frames
a transition between wall and adjacent roof
require a gutter at the edge of the roof,
deck or ground conditions. The hybrid struc-
which cannot always follow the geometry
tures with their tree-like base use a range of
of the frame itself A solut ion is to set the
curved and welded steel plate and cast con-
external envelope away from the portal
nections to create complex forms that serve
frame, usually by settingthe purlins on the
as moment connections that can contrast
outside edge of the portal frames, thus creat-
visually with adjacent pinned connections at
ing a gap between frame and envelope.This
roof level. Generally, the use of portal frame
gap can then accommodate the shape of the
structures as single enclosures suggests a
gutter wit hout interrupting the visual line of
continuat ion of the interdependency of
the roof / wall enclosure on the outside.The
structure and envelopethat are clearly visible
inside face of the external skin can also be
in contemporary examples.
Fawood School. London. Architects: AlsopArchitects
lined to conceal the gutter if required.The
MCH
307
Structure Loadbearing boxes I: reinforced concrete
--
In this section are considered structures
projects where a high degree of repetition
where loadbearing walls and floors are
occurs in panel types. Concrete loadbearing
linkedtogether with some degree of inter-
boxes have the advantage of high fire resist-
dependency. Although not strictly regarded
ance combined wit h high sound insulation
asa structural system, techniques of load-
from both airborne and impact sound. Con-
bearing concrete wall and floor construction
crete can be used in conjunction with both
are very common in Europefor large-scale
steel and concrete structures. In situ cast
housing projects. Many European houses are
techniques generate a monolithic connection
built with loadbearing masonry walls with
between floor and walls. Precast compo-
either timber or concrete floors that provide
nents are stitched together to form a similar
stability to the external walls.
connection. Since concrete is not regarded as vapour-proof,the outside of the concrete
Concrete loadbearing boxes Loadbearing walls and floors made in
is eit her rendered or covered with a cladding system,typically a rainscreen. Measures
reinforced concrete can be combined to
to ensure thermal insulation,together wit h
makea complete monolithic structure.Both
finishes, are discussed in the in-situ cast walls
in-situ castand precast concrete techniques
section in chapter 2.
can be used,though precast methods suit MCH
308
Details I. External wall 2.W indow opening
3. Floor slab 4. Parapet upstand 5.W indow frame
Tod's Building,Tokyo, Japan. Architects: Toyo Ito
Timber form-Work used to achieve decorative texture
MCH
309
a
Structure Loadbearing boxes I: reinforced concrete
CAC Museum, Cincinatti, USA. Arcitects: Zaha Hadid Archit ects
MCH
310
Details I. Extemal wall 2.Window opening
3. Floor slab 4.W indow frame
CAC Museum, Cincinatti, USA. Arcitects: Zaha Hadid Architects
MCH
3 11
Bryanston School, Dorset. Architects: Hopkins Architects
-:
r
Loadbearing brick structures are rarely used in buildings in the industrialised coun-
/>
/'
x x
useis discussed in the Walls chapter. The use of brick in these structures
(completed 1983) both designed by Louis Kahn.The architect had previously used brick
tries since they are more expensive than
is restrictedto the walls, since traditional
slips (thin brick tiles that imitate brickwork)
cavity walls, usemore material and are slow-
vaulted brick floors have been superseded
to conceal openings formed in either steel
er to build.Traditionally,they have also been
by timber or concrete floor construction,
or concrete. In these two projects structural
less efficientat excluding rainwater than
which can more easily achieve longer spans.
brick arches are used. Because of their large
contemporary cavity walls, with the separa-
Loadbearing walls are usually muchthicker
size, spanning up to approximately three
tion of internal and external skins that has
than their cavity wall equivalents, making the
metresthey were combined with reinforced
made cavity wall construction a technically
structure much heavier, in order to provide
concrete lintels as tied arches.The ends of
accomplished and less expensive alterna-
sufficient waterproofing, since the brick
the ties were specially formed to bond into
tive to solid, loadbearing construction. Over
absorbs rainwater nearthe surface and later
the adjacent brickwork,thus avoidingthe
the past 100years, the design of brickwork
dries out.Traditionally, openings in walls have
need for additional steel connectors.
has generally aimedtowards increasing its
been made with arches of the same material
strength through the useof higher strength
as the surrounding wall and in flat, curved
mortars,though this results in a more brittle
or pointed variations. Flatarches require
structure with reduced flexibility that was
considerable skill to construct, and are often
has loadbearing brick walls,which consistof
provided by the lime-based mortars.This
reinforced with bed reinforcement in the
tw o skins 220mm thick with a SOmm cav-
has led to the need for movement joints in
form of steel rod or expanded mesh. In
ity providing acoustic separation.The inner
the material, usually at around 6.5 metres
common wit h other types of masonry con-
leaf supports the back of the balconies.The
centres, with the effect of loadbearingwalls
struction, brickwork cannot be loaded, and
brickwork forms a loadbearing drum, 33.7m
becominga series of linked panels.The
will fail in tension.
A recent built example Glyndebourne Opera House in England
in diameter, 17.7m high, truncated on one
gradual re-introduction of lime putty mor-
Loadbearing brickwork was used in the
tars,wit h their lower strength but greater
Indian Instituteof Management at Ahmeda-
From this wall radiates a series of precast
allowance for movement, is set to change
bad, India, (completed 1974) and part of
concrete panels that form the soffit to the
the nature of loadbearing brickwork,and its
the NationalAssembly at Dhaka, Bangladesh
balconies and partially support the seat-
MCH
312
face where it intersects wit h the fly-tower.
2
D etails I. solid structural brickwork pier 2. Brick arch
3. Precast concrete floor beams with padstone 4.Aluminium window frame 5. Loadbearing brickwork wall in
3-D sectional model showing loadbearing masonry construction
English Bond
MCH
3 13
Three Brindleyplace,Birmingham, England, Archit ect: Porphyrios Associates,
3-D elevation of typical loadbearing brick bay
ing above, In-situ cast columns that are tied
overall compressive strength of 6.2N/mm2,
applications are set to revitalise the use
together wit h an in-situ casttopping and ring
which is less than halfthat of convent ional
of brickwor k as they start to combine the
beam provide addit ional support.W here the
brickwork at around ISN/mm2,
authenticity of loadbearing walls with con-
structure runs alongsidethe side stages, the inner wall becomes an acoustic wall.220mm thick, but elsewhere it is less dense, and
temporary requirements for weatherproof-
Current applications The use of loadbearing brickwork in
ing and thermal insulation,An advantage of loadbearing brickwork is its ability to vary
where it is punctured by openings. providing
recent economic applications has been
in thickness to suit structural requirements
access to the auditorium, it becomes a series
mostly in situat ions where thermal insulation
without the need for the stainless steel fix-
of piers,The walls supporting the balconies
is not required, such as in wallsset externally
ings and supports associated with cavity
are 334mm thick continuous skin,sup-
to form a screen wall to external spaces, or
brick walls, where any modelling of the sur-
ported by fiat arches resting on gently taper-
semi external spaces. Alternatively, the load-
face of the wall is difficultto accommodate
ing brick piers,The mix used for the lime
bearingwall is used in a hybrid condition,
structurally due t o the nature of its construc-
putty mortar in the brickwork was a I:2:9
where it supports itself in the manner of the
tion' which is to be non-Ioadbearing. Load-
(cement lime putty:sand) ratio by volume,
outer leaf of a cavity wall,but is only con-
bearing brickwor k is also able to use other
The cement gave early strength to the wall
nected at points to the floor slabs behind in
materials in its construction, from cut stones
and slightly improved durability and weather-
order to reduce the thermal bridge through
forming pieces of loadbearing archesto pre-
ing.The compressive strength of the bricks
the material.Thermal insulation,when
cast concrete ties, lintels and cills as an inte-
was 27.5N/mm2 and that of the lime putty
required, is set on the inside face of the wall,
gral part of the construction,The additional
mortar was I.5N/mm2.This provided an
and is also set between slab and wall.These
cost of this form of construction over that of
MCH
314
G)
-:
/
./
G)
/
-;/
3-D Section th rough typical loadbearing brick bay show ing concrete beams supported on br ick piers and brick arches cavity wall constr uction makes its applicat ion less wi despread, but th is may change with the possibility of prefabricating sectio ns of t he wall away from t he site, and assembling
Det ails I . solid structural brickwork pier 2. Brick arch
the pieces on site in the manner of precast
3. Precast concrete floor beams
concrete construction , w here speed of con-
with padstone
struction is a benefit. Some recent examples have set steel reinfo rcement int o the depth of t he w all so as to increase it s strength, and
4.A luminium wi ndow frame 5. Loadbearing brickwork w all in English Bond
resistance t o w ind load, w it ho ut increasing it s th ickness beyond o ne and a half bri cks th ick, whi ch is generally considered to be t he minimum thi ckness of loadbearin g walls w hich can exclude rainwater (thou gh thi s is not always sufficient, of course) .The use of ste el reinforcement can help reduce th e overall w eight of t he w all in ord er t o remain w it hin the loadbearing capacity of th e wa ll.
MCH
315
tructure 021 Loadbearing boxes 3: glass
Broadfield Glass Museum, West Midlands, UK. Architect: Design Antenna
All-glass loadbearing structures are a
MCH
316
stainless steel brackets or shoes which are
recent development in the design of small
bolt fixed to the double glazed unitsforming
scale glass enclosures,Their intention is
the external wall.The beams, fins, wall panels
usually to maximise transparency, andtheir
and roof panels are bonded together, typi-
application on single storey enclosures
cally with silicone, to form an all-glass struc-
ensures that glass sheets can form walls
ture, In practice, most all-glass structures
without the need for aluminium or steel
have additional mechanical fixings to secure
framing,Typically, double glazed units are
all components, as a completely bonded
set vertically, with examples ISOOmm wide
glass structure has obvious risks associated
x 3000mm high, These larger size pan-
with its design, A typical fixing might be a
els require glass fins set verticallyto take
toggletype fixing where a flat metal plate
the place of glass mullions, but glass units
is used to hold double glazed units in place,
2100mm high sometimes do not require any
The double glazed units have an edge spacer
glass fins, depending on the wind load, Dou-
with a groove aroundthe edge to which
ble glazed units are also used to form roof
the toggle plate can be fixed,The silicone
panels, set onto glass beams which are fixed
between double glazed unitscan then be sili-
to the vertical glass fins, Where no vertical
cone sealant rather than a silicone bond,The
fins are used, the glass beams can be fixed to
junction between vertical glass fins and glass
Details of glass load be ar ing boxe s I. Triple glazed unit 2. Laminated glass beam with slot for column
3. Laminated glass column with projectin g lamina that slots into beam
Internal view of ~ructu ral glass box assembly
beams supporting the roof panels may still use a silicone bond .The glass ty pes used are a combinat io n of te mpered and laminated glass which is bond ed or bo lted toget her
3-D exploded view of structu ral glass box assembly
All-glass enclosure, Broadfield Glass Museum,We5t Midlands, England.
(3)
/
The architect w as Brent Richards of
t o form beam and column compo nent s. In
D esign Antenna wo rking w it h structural
common wit h bolt fixed glazing, an essential
engineers of D ew hur st MacFarlane.T he
consideration in the design of loadbear-
enclosure is constructed without metal fix-
ing glass structures is the avo idance of any
ings or supports in any another mater ial. It is
stress concentrations that might lead to
I Im lo ng, 5.7m wi de and 15m high.The pri-
glass breakage w hile th e stru cture is under
mar y structure consists of glass beams 5.7m
normal load conditions. Since the techni ques
long x 300mm deep, at I OOOmm centres .
used are very recent, no general pri nciples
O ne end is supported by an existing mason-
for construction are set o ut here but two
r y wall, w hilst the ot her is supported o n
recent examples are shown. Someti mes a
glass columns 1 5m high and 200mm deep.
glass fin can be used at roof level on ly.pro-
/
The beams and columns are made from
jecti ng down th e wa ll for a short distance
three sheets of glass laminated together,
and remaining above head height to avoid
making them 32mm thic k.At the rear,the
risk of injury to user s.
beams are secured by shoes in steel fixed to
..
3-D exploded view of structural glass box assembly
MC H
3 17
House extension, London,Architect: Paul Archer Design.
the wall. while on the glazed side they are connected to the columns in an interlocking ofthe glass layers.The junction was bonded on site with a catalyst-cured resin.The glass roof panels are bonded to the top of the glass beams.The double glazed roof panels have an outer layer of IOmm thick toughened glass. a I Omm air gap and an inner skin of two sheets of 6mm glass laminated together. A silver film on the inner face of the upper sheet reduces solargain,as does the ceramic fritting on the inside face of the panel. The roof panels are bonded to the beams with structural silicone bead with a rigid foam backing.The gap between the panels is sealed using a silicone-rubber weather seal wit h a foam backing.The roof slope is 1.s°.The roof can be walked upon for maintenance, and supports expected snow loads.The front walls consistof 3.7 metre x 1.1 metre high double glazed panels composed of two sheets of 8mm toughened glass with a IOmm air gap. 3-D view of structural glass box system
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318
Details: Glass loadbearing box I.Triple glazed glass beam 2. Double glazed unit 3. Stainless steel bracket bolt fixed to beam and wall 4. Bonded glass connection
Glass footbridge 5. Glasswall panel 6. Glass roof panel 7. Glass sheet as fioor deck 8.Laminated glass beam 9.Steel frame at each end of bridge
Horizontal section 1:5through roof beam
Glass footbridge. Rotterdam, Holland. Architect: Dirk Ian Postel
All-glass footbridge, Rotterdam, Holland This footbridge was designed by the architect Dirk Jan Postel of KraaijvangerUrbis, working w it h Structural Engineer ABT Velpe.The bridge spans three metres w it h fioor plates of ISmm laminated fioat glass supported on two laminated glass beams made from fioat glass.The side-walls consist of double glazed units made from IOmm and 6mm thick toughened glass sheet. In addition to being self-supporting, the walls support the glass roof. which has the same type of laminated construction asthe walls. The all-glass components are fixed together wit h stainless steel brackets and plates. The use of stainless steel fixings does not noticeably reduce the transparency of the structure, adding a sense of visual refinement, while the curve of the beams supporting the fioor deck contrasts wit h the rectilinear design of the glass enclosure. From a visual point of view,the all-glass design makes it easy to link wit h existing buildings on either side.
3-D exploded viewof footbridge assembly
MCH
3 19
Traditional timber roof truss assembly Truss types. a. Warren truss G) b. Modified Warren truss. c. Pratttruss. d.Vierendeel truss
and tension flanges to generate a greater
effects, the cross-sectional shape for indi-
a solid girderwould be at a disadvantage
moment of resistance in order to provide a
vidual truss members can vary enormously,
due to its self-weight. Instead of using a
greater loadbearing capacity while minimising
since truss members are generally subjectto
deep solid section, such as a girder, a more
weight. Simply supported trusses exert no
small direct forces. Consequently,T-sections
economic solution for larger spanscan
thrust at their supports allowing them to be
and tubes can be used in steel trusses, for
be provided bytransmitting forces across
easily supported on columns or supporting
example, while a mix of timber and steel
a series of diagonally set and connected
can be used in other types. Flat shaped sec-
members to take up the vertical, horizontal
walls within a larger structure. Truss types vary enormously in their
tions make the connections easierto form
and diagonal shear stresses. With the excep-
design; the most commontypes being the
than box sections, but this situation provides
tion of the Vierendeel type,trusses use
Warren trusses, where loads are carried
opportunities to design elegant connections,
pin-ended members that utilise tension and
mainly as axial loads in the members, the 'N'
which can be one of the most significant con-
compression in a series of ties and struts.
truss which has vertical and diagonal mem-
siderations from a visual point of view.
Trusses are used for large spanswhere
Whiletrusses bend along their overall length,
bers in a rhythm of alternating tension and
Joints and connections
local bending within the truss can be largely
compression, and the Vierendeel truss, which
avoided ifloads onto the truss are applied
has an orthogonal rather than a triangulated
at the node points. Loading trusses away
series of members. In the Vierendeel truss,
mild steel or a combination of the two
from the nodes introduces local bending
forces are transferred between members by
materials. In trusses using mixed materials,
into horizontal members with a resulting
localised bending, called Vierendeel action,
steel rod or cable are used to form the ties,
increase in their design size, as members
with rigid connections between members. As
typically on the bottom chord of the truss,
now have to resist bending as well as axial
such, it is not strictly a truss type.The bend-
while steel tube might be used to form the
loads, resulting intrusses that are heavier,
ing makes members slightly larger than in an
central strut.Timber roof trusses are either
usually less elegantand more expensive.The
equivalent triangulated truss,resulting in their
large trusses set up to three metres apart
Trusses are typically formed in timber,
voids between members are often used
being heavier than a Warren truss spanning
linked together with purlins or much lighter
to accommodate services and mechanical ventilation ducts.These structures maximise
the same distance. Whereas beam members are predomi-
nail plate trusses set at around 450mm centres. Larger trusses often use double timber
the leverarm between the compression
nantly I-shaped to accommodate the bending
members forming the main rafters and joists
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320
Timber tru sses in t ree-like arrangeme nt.
Resource Centre, Grizedale, Cumbria.Architects: Sutherland Hussey Architects
Details I. Purlins spanning between tru sses 2. Roof cove ring 3. Str ut 4.Tie 5.Timber wa ll plate 6. Bolte d steel con nect ion 7. Stee l conn ector plate
1/
/
I
/
I
X
-~---
Ve rt ical sectio n I:20 through trtypical timber tru ss roof
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321
Details I . Purlins spanning between t russes 2. Roof covering
3. Strut 4.Tie 5.Ti mber wa ll plate 6. Bolted steel connection 7. St eel co nnector plate
Detail of wall plate connection
(j)
•
Steel plate connecting timber elements at roof ridge
Typical exposed roof truss
MCH
322
that are spaced apart with secondary ties
members in order to minimise the diameter
and struts which linkthe primary members.
of the tubes. Modest steel trusses use angles
Timbers are bolted together using large steel
set back to back and bolted together with
washers that spread the load imposed by the
gusset plates set between them to allow
bott head and prevent it from crushing the
several members to be joined together at a
timber locally as the connection is tightened.
single node.They are inwidespread use as
The exposed steel components are painted
economic longspan supports to roof struc-
to avoid their corrosion.Timber trusses
tures. Larger scale trusses are made from
can also make use of ties made in steel rod
laminated timber or LVL (laminated veneer
where they are visible components. Smaller
lumber),which resembles plywood in its con-
trusses are factory assembled with nail plates
struction but is made in long lengths.These
and split ring connectors as described in the
materials use similar bolted connections to
Materials chapter. Steeltrusses can range
smallertrusses, but typically with bigger metal
from a modest set of angles bolted together
connector plates.Truss members can be
with linking gusset plate connectors to weld-
made from single lengths of LVL, but for high
ed tubular structures that can incorporate
loads, LVL is glue-laminated to make large
cast node connections to allow connections
cross-section members,typically square in
with complex geometries to be formed.
profile. Reinforced concrete trusses are usu-
These cast connectors allow the loads to
ally precast either as a series of prefabricated
meet at the intersection of the centrelines of
components which are stitched together
Timber truss with steel trussties
Timber truss wit h steel truss ties
Steel ties act as truss in both directions along the length of the roof
or as a single completed component.They
local bending intruss members,the fixing of
are much less commonly used than those in
cladding to secondary supports permits the
timber or steel due to their self-weight. which
use of simple bolted or screwed connec-
tends to reduce the lightness and economy
tions that avoids any complexity in fixing to
associated with trusses.
a primary member.The bases of trusses are set either onto a supporting structural frame
Interface with external envelope Trusses are tied together by the secondary members called purlins which connect
or onto a supporting wall.The wall plate or purlin joiningthe base of the trusses is typically used to form an interface between
trusses together,typically points on the rafter
roof covering and the external wall below,
which intersect wit h other tr uss members,
where a gutter is typically required.The
called node points.The purlins are set on
arrangement of purlins is often adjusted to
top of the outer face of the truss in order to
suit the needs of supporting the roof cover-
form a support for the build-up of the roof
ing,which may range from profiled metal
covering and to make a simple connection
sheet to traditional roof tiling. Steel trusses
between truss and purlin. Purlins can have an
may also have brackets fixed to the top of
internal finish applied, such as timber boards
the truss to provide connectors to the roof
or dry lining in order to expose the trusses
covering,typically with the aim of providing a
within t he building, but this varies with the
visual separation between structure and roof
Visito r Centre Koga Ibe raki Prefactu re, Japan.
design of t he tr usses. In addition to avoiding
covering.
Archite cts: Naito assoc iates
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323
Siobhan Davies Dance Studios, London. Architects: Sarah Wigglesworth Architects
Section th ro ugh shell I.Timber member 2.Steel rod 3. Steel node connector 4. Doubled glazed unit
The essential concept of th e arch is t o suppor t load s primarily as compression
Arches The rigid arch has no pin jo ints, but
becomes shallower. Bot h t he t hree -point and two -po int arches suit larger spans which
forces in the plane of t he str ucture , wit h
instead has rigid connections at both base
wo uld present difficulties for tr ansport and
abut ments at the base to resist the o utward
points.This arch type is generally considered
handling if made in a single piece .The most
th rusts gene rated by its shape. Since arches
to be more econom ical than the two ot her
commo n mate rials used are stee l, laminated
exert outwa rd forces at their bases, t hey
types, but has bending moments at its base
t imber and reinforced concret e.
requ ire a tie such as a floor slab or beam, for
that are transmitted into the foundat ions,
example.This is qu ite different to some por-
which may need t o be linked by ground
tal frames , which do not exert such forces at
beams to resist t he thru sts, in the manner of
thei r base po ints. Co nsequentl y, a variat ion
a t ied arch, unless the ground is sufficient ly
to th is type is the 'tied arch' in which a ten-
firm to wit hstand the th rusts wit hout a
ding is app lied and monolithic she lls which
sion member li nks t he base points across
beam .The two-pin arch has pin joints at the
are made either by casting concrete in place
the arch to resist t hese outward thrusts and
abutm ents only It is more economical in
over com plex formwo rk or as precast sec-
control spread ofthe arch.The t hree most
materia l than the three-pin type and bending
tions which are stitched togeth er. In both
com mon types used in modern construction
mo ments are mo re evenly distributed t han
cases,the loads are carried in t he plane of
are the rigid arch,th e two -pin arch and t he
Shells Shells are of two generic types;t hose made from framing memb ers to which clad-
in the t hree-pin type , minimising the amo unt
the structure wit h the outw ard th rusts being
three-pin arch.These tw o-dimensional struc-
of material used.The th ree -pin arch is hinged
taken out at the base . Shells constr ucted
t ures are lin ked t ogether in bays with purlins
at th ree points, which are at the apex and at
from framing membe rs often have a ring
to form a complet e structure.Alternatively.
the two base points. Bending does not occur
beam at t he edge to cont ain the effects of
the arch concept can be extended into
at t he pin joints,which behave as pivots or
the outward thru sts. Monolithic concret e
t hree dimensions as a shell. Both arches and
hinges. Bending moments away from the
types may eit her follow the same principle
shells can be formed eit her from t russ com-
pins are greate r than in ot her types.As with
or have a continuous abut ment at their base
ponents, as 'gridshells', which are in increased
th e t raditional masonry arch,there are hori-
to deal with the higher loads associated with
use , or as mon olithic structu res in reinfo rced
zontal th rusts at the supports.Thrusts at th e
co ncrete. Shells in which the structure and
conc rete .
base of an arch increase as the arch profile
enclosure are combined in a single form,
MCH
324
3-D view of timber shell structure with tension cable support and double glazed roof
MCH
325
tructure 04 Arches and shells Section through shell I, Reinforced concrete outer shell 2, Concrete edge beam
3. Concrete ribs 4, Steel connectingbrackets
3-D view of shell structure with precast concrete panels supported by stee l grid structure
Yatsushiro Municipal Museum, Kumamot o Prefuctur e,japan,A rchitects:Toyo Ito & Associates,
as found in an egg shell, are referred to as
material. An essential aspect of framed shells
monocoques, Shel l forms vary enormously,
or 'gridshells', with their double curvature, is
from the relatively simple shell vault resem-
the connector node,which is typically made
bling an extruded arch, to the complex
in steel and which can also be used to sup-
ribbed structures resembling seashells,
port the roof covering,Where a single material is used for the gridshell,such as steel,
Joints and connections
MCH
326
node connectors are not required ifregular
Arches and shells made from fram ing
cleat and bracket connections can be used
members (rather than reinforced concrete)
economicallyThis allows the roof covering
are formed using the pinned and moment
to be supported directly on the structural
connections associated wit h each mate-
members, Shells can be supported at their
rial and are illustrated here,An interesting
base on a variety of supports,from columns
recent development has been in using a mix
to loadbearing walls or floor slabs.The
of materials to form shell structures, such as
choice of support may be related directly to
those in timber and stainless steel cables or
the need to provide an economicweather-
rods,The mixing of materials has benefits in
tight seal at their junction,though structural
economy of weight, allowing forces in differ-
ring beams are often needed to contain the
ent members to be matched to a suitable
outward thrust forces,
3-D view of shell structure with precast concrete panels support ed by steel grid structure
Interface w ith exte rnal envelope Monolithic arched structures and shells
can be supported as clamped glazing supporte d at the node connector points, or
are covered externally in continuous mem-
alternatively from a secondary metal frame
branes where rainwater is collected at the
also connected at these node points.The
base of the structure. Membranes usedvary
external envelope is fixed in a way which
from polymer-based typesthat are bonded
allows the structural movements of grid-
to the structural substrat e,to standing seam
shells, which can be higher than other types
metal sheeting.
of roof structure,to occur without damage
Trussed arches and gridshells provide
t o joint s in the roof covering.While move-
the opportunity for transparency, where
ment s can be more easily accommodated
glazed roof systems can be used in addition
in metal roofs, glazed roofs require careful
to metal clad roofs.Where metal is used,a
particularattention to detail to ensure that
covering of sheet metal or metal rainscreen
the support points for the glazed units do
panels are used,typically with a profiled
not experience significant amounts of move-
metal substrate serving as a deck, though
ment.Consequently,t he principles associated
the double curvature of the shell can make
with point fixed glazing are often used, even
it easier to form a substrate from triangles,
where part of the support system involves a
which are always flat. Double glazed units
metal support ing frame.
Yatsushiro Municipal Museum, Kumamoto Prefucture,Japan.Architects:Toyo Ito & Associates.
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327
Plan and section I. Node co nnecto rs 2.To p chords of frame
3. Bottom cho rds of frame
3-D view of space frame structure supporting a glass roof and facade
Space frames and geodesic domes are
lent of the space frame for curved surfaces
stiffness of the material combined with its
the most well known types of space grid.
is the geodesic dome,originally developed
comparatively low cost.
They can be regarded, from a conceptual
by Richard Buckminster Fullerin the I940s.
point of view as being three-dimensional
Fullerbelieved that structures in nature
trusses. One of the earliestspace frames
behave in a waythat internal forces usually
The 'base' component of space frames
wasthe Mero system designed in the 1940s
act in the direction of minimum effort with
andgeodesic domes can be considered to
by Max Mengeringhausen, and is still used
a maximum gain achieved with a minimum
be a square-based pyramid-shaped frame,
today, though much evolved from that time.
of energyinput.Rather than apply this idea
assembled with rods or tubes connected
A development by Konrad Wachsmann
to the form of the plant leafor the animal
by a single node connector.The early Mero
Joints and connections
in the I950s was based on the geometric
shell, Buckminster Fullerinterpreted trian-
systems used a spherical node with threaded
form ofthe tetrahedron.The space frame
gularcrystalline forms found in nature, using
holes set into which eightconnectors fixed
comprises a series of triangulated members
triangulated frames. Like the space frame
to structural members forming the space
linked by node connectorsthat, effectively,
the geodesic dome is essentially a continu-
frame could be connected. Four holes were
form a series of linked trusses in directions
ous triangulated structure but its geometry
set in onderto allow members all in the same horizontal or vert ical plane to be connected
perpendicular to one another.The mate-
often allows it to be used as a single-layer
rial system is made economic and fastto
structure wit hout the need for introducing
together, wit h four additional holes at angles
install by using a single node type where
triangulation into the depth of the structure.
that allow triangulated members formingthe
ever possible, though different connectors
Space grids provide long-span structures
depth of the space frame to connect to form
may be used at the edges where they meet
for roofs and walls.They can take on a huge
the characteristic triangulated shape. More
the external wall.Somegeometries require
variety of forms from vaults to supporting
recentversions usesquare- and polygon-
a 'family' of connectors to form complex
structures for large glazed walls. Deflections
based geometriesto fonm the node connec-
shapes, particularly those space frames that
in space frames are small due to the overall
tor, allowingtriangular gridsto be used rather
depart from the square, rectilinear format
stiffness of the frame. Steel is most com-
than the square-based versions.The new gen-
that has been used until recently. An equiva-
monly used because of the strength and
eration of nodes can be used for single layer
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328
Details 4. Spherical cast connector 5 Drained and ventilated cladding panels (acrylic roofiights shown) 6. Rubber-based seal
Eden Project, Cornwall, England.Architects: Grimshaw Architects
Eden Project, Cornwall, England.Architects: Grimshaw Architects
Typical space frame
3-D view of space frame structure support ing a glass roof and facade
MCH
329
Eden Project, Cornwall, Architects: Grimshaw Architects
3-D views of space frame structure support ing a glass roof and facade
MCH
330
Eden Project, Cornwall. Architects:Grimshaw Architects
Eden Project, Cornwall. Architects: Grimshaw Architects
Typical nodes and chords of a space frame structure
structures that are more based on the ideaof
for additional rails or purlins. For glass roofs.
gridshells than space frames, andallow more
a typical distance of ISOOmm between
node.Cladding conditions can vary from flat.
freedom in the range of angles that can be
horizontal structural members in the space
to inclined, to curved, followingthe geom-
accommodated in order to allow more geo-
frame allows economic sized double glazed
etry of the supporting structure to which
metric variation in the form of the grid.The
units of the same size to be used. Where a
they are fixed. In conditions where the roof
design of nodes iscurrentlymoving towards
profiled metal deskis used. there isgreater
is horizontal. the roof covering can drain to
this preference in design for a wider range
flexibility in the size of the structural bay. as
gutters set between roof panels, following
of formsthan that affonded by the rectilinear
the decking can span up to around 3S00mm
the direction of structural members beneath.
frame arrangement.
with standard profile depths. Roof cladding
In conditionswhere the roof is inclined, the
or glazed panels are fixed either with lugs
roof covering is drained like a glazed roof,
The essential component of the space
glazing can be fixed directlyto the structural
grid isthe node connector.Very simple types
or brackets welded to the structural mem-
with water runningacross the roof surface
with simple geometries usea flat plate con-
bers. which may be tubular or rectangular.
to gutters at the edges. Glazed roofs in most
nector to which steel angles are bolted in the
Alternatively. the roof covering can be fixed
geometric conditions useglazing which is
mannerof a truss. Complex geometrytypes
to the node connectors where the node is
toggle fixed or point fixed,with a single
use a cast or machined node that has thread-
designed for this purpose. More typically. the
silicone-based seal set flush with the surface
ed holes to receive the ends of the threaded
nodes are used as structural connectors only.
of the glass. in order to allow rainwaterto
connectors of the ties and struts.These form
Where a rectangular hollow section is used,
run freely across the roof.
part of proprietary systems designed by
cladding can be fixed directly to structural
manufacturers.
members without the need for welded
glazed space frames typically use either a
lugs, provided that the potential corrosion
glass to glass joint, or one where an insulated
caused by penetrating the tube istaken into
metal panel is used to form the junction.The
account.
choice is largely based on design preference,
Interface with external envelope An essential advantage of the space grid isthat cladding panels can be fixed directlyto the structure without the need
Point fixed glazing is also suitable for
Junctions between wall and roof in
and the visibility of the glazed edge.
space grids since the connectors for the
MCH
331
I: cast-in-situ/cast-in-place concrete
Reuters Building,London, UK. Architect: Richard Rogers Partnership.
;l
GD-------------------gj--------------------· a
---------~----------~;;;:::-----4------;---Gl
(3)
;l
;lZl
~~Z
Vertical section I: 10.Typical floor slab build up
The fiat slab isthe simplest type of east-
is concentrated can reducethe depth of fiat
must be specially made.
in-place fioor and is suitable for spans up
slabs.These caps provide greater rigidity for
to around nine metres. It can be used in a
the structure and reduce the span of the
reinforced or poured as mass concrete.
one-way or two-way span, approximately
slab between columns.
depending on the degree of strength and
300mm deep. depending upon span and
Floor spans can be increased economi-
Ground-bearing slabs may be either
rigidity required. Where ground-bearing
loading. In a one-way span. steel reinforce-
cally from six metresto 15 metres by form-
conditions permit.they are supported
ment is introduced into the bottom part of
ing a series of downstands in the fioor soffit
directly by the ground beneath. Where the
the slab and the fioor is designed to span in
to create a ribbed fioor. Steel reinforcement
ground istoo soft. a suspended fioor is used.
one direction only, like a beam. In a two- way
in the bottom of the ribs makes this type of
Ground-bearing slabs can be designed either
slab. the reinforcement is laid in a perpen-
fioor lighterthan the fiat slab because of the
as a raft or as a slab supported by separate
diculargrid so that the total load of the fioor
structurally efficient ribbing but the form-
foundations beneath. Ground slabs are laid
is more evenly distributed at its perimeter as
work is more complex.
on a compacted base of hardcore (gravel).
the fioor spans in two directions. Reinforce-
The two-way coffered fioor slab is a
ment is concentrated on the lines between
ribbed fioor for large spans up to around 17
which provides a level and well-drained base.The hardcore is blinded with a smooth
columns to create beams connecting col-
metres in tw o directions.The hollow coffers
layer of sand onto which is laid a damp-
umnswithin the depth of the slab.The soffit
are often used to house lighting and serv-
proof membrane (DPM:vapour barrier).
is fiat. providinga smooth ceiling and allow-
ice outlets.The fioor structure gives better
The sand prevents the DPM. usually a thick
inga straightforward type of formwork to
resistance to shearwhen the beams are set
polythene sheet, from beingpunctured by
be used. Providing the tops of columns with
diagonally to the structural grid of columns
the hardcore.The DPM prevents moisture
protruding caps where the transfer of forces
but as with ribbed fioors,the formwork
rising up through the slab.The concrete is
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332
2.Slab wit h downstand beams
Typical in-situ concrete towerconstruction showing form work ontop two floors
Sections through floor slabs I. Screed 2. Concrete
3. Damp proofmembrane (DPM) 4. Sand blinding 5. Hardcore 6. Earth
poured directly over the DPM. In addition,a DPM can be laid between the concrete slab
3. One way spanning ribbed slab
and the screed.A liquid material is used to provide a bond to the surface of the slab.This results in a loss of bond between the screed and the slab, and a thicker screed (about 75mm) is used.The DPM is joined to the wall DPC (damp-proof course: vapour barrier) to provide continuity of damp-proofing .A DPM laid on top of the concrete,usually in the form of a liquid-applied layer. is used as an alternative where sealing the underside and edges of the slab is not practical. Distribution bars (reinforcing mesh) are set near the reinforcing bars in order to avoid cracking in the underside of the slab due to its being in tension under load. Reinforcement used in concrete fioors can be either conventional reinforcement bars or welded mesh fabric. 4.Two way spanning ribbed slab
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333
Structure 0 Floor structures 2: precast concrete
3-D deta il of advanced beam and block syste m using expanded polystyrene blocks
3-D detail of traditional beam and block floor syste m
Details I. Concrete block 2. Prestre ssed concrete beam
3. Expanded po lystyrene block 4. Structural concrete topping S. Ho llo wcore slab 6. Primary stee l structure
3-D detail of ho llowcore system suppo rt ed o n steel primary str ucture
7. Struct ural concrete infil 8. Reinforceme nt tie
construction,which has the advantage of
additional sheet insulation withinthe fl oor
Precastconcrete floo rs consist of
a rapid rate of construction.All types can
system. Pre-stressed concrete beams are
prefabricated planks or beams connected
be lefteither exposed, as is sometimes the
placed at 620mm centres before the poly-
together to form a deck. Proprietary systems
case with parking garage construction, or be
styrene blocks are fitted between them.A
provide longer spans than in-situ-cast con-
topped with a layer of concrete to form a
structural concrete topping adds strength to
crete floors but they span in one direction
composite structure. Openings for service
the system and provides a smooth topping
only. Precastfloors that span two ways have
runs need to be fixed at an early stage, since
to which internal fini shes can be applied.
been developed for specific projects such as
the size and position of openings in precast
the Richards Medical building shown here,
floor systems is much more constrained than
and go beyond the constraints imposed by
isthe case for cast-in-place floors.
standard systems.
The generictypes produced by manufac-
Hollowcore flooring systems use large pre-cast slab elements supported from a
Beam and block System Proprietary systems
Hollowcore systems
A traditional beam and block floor uses
structural frame to create large clearspanning floo r systems.The hollowcore system
pre-stressed concrete beams to support
can be used with the majority of structural
turers are as foll ows:
aggregate concrete blocks.The beams are
framing systems including masonry, steel
I. Beam and block, spanning to around 7.5
spaced at various centres depending on the
and concrete. Masonry bearings need to be
metres
applied loads and internal plan configu ration.
inthe region of IOOmm,whereas 75mm is
2. Hollow core slab, spanning to around 12
Beams may need to be staggered or dou-
needed for bearings on steel or concrete.
metres
bled up to support internal walls. After the blocks have been positioned
Hollowcore slabs can span up to 12 metres and panels are typically tied over
a grout consisting of a mixture of sand
supports with a tie reinforcement and
beams,which are stitched together to form
and cement is brushed across the floor to
structural concrete infill. Holes smallerthan
a complete deck. Ends are supported either
ensure all joints are evenly fill ed.The use of
[OOmm should be drilled on site. Larger
on beams or by a loadbearing wall, typically
expanded polystyrene blocks in the place
holes can be formed during manufacture
formi ng part of an overall precast concrete
of concrete blocks eliminates the need for
and may need steel trimming supports.
These are all essentially prestressed
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Richards Medical Research Laboratories Richards Medical Research Laboratories, University of Pennsylvania, Philadelphia, USA. Louis Kahn.A series of interlocking beams provides a floor structure whose exposed soffit could be clearly articulated as bays formed by primary and secondary beams. This approach contrasts with that of the flat slab.
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Structure 04 Floor structures 3: steel and steel mesh
3-D detai l of compos ite floor co ntructio n
Composite floor details I. Concrete to pping 2. Light reinforcing bars
3. Profiled steel dec king 4. l-section beam 5. Steel plate bo lte d o r welded to l-section 6. End fi lle r piece to form edge of poured conc rete
3-D detail of completed composite floor
Although it is possible to makean all-
simply supported situation,the concrete is in
Steel mesh floors
steel floor, in practice it is structurally inef-
compression andthe steel is in tension.The
ficient and difficultto provide the necessary
economic use of this type of floor is limited
trial buildings and on maintenance access
fire resistance, impact resistance and sound
by its span.Over large distances, the sup-
decks in other building types such as offices.
insulation. In addition,the amount of steel-
porting beams become very deep,resulting
It provides a lightweight, economic deck
work fabrication required would make it
in an increased floor-to-floor height.
material that allows rainwater to drain off
very expensive.The use of all-steel floors is
The profiled decking is fixed to the sup-
Steel grating is used primarily in indus-
it immediately, making it less susceptible to
restricted to steel grating in areas that are
porting steel beams with shear studs which
corrosion when painted or galvanized. Steel
not required to provide fire resistance. AII-
provide the composite action between slab
grating is usedto make structural decks
steel floors in sheetand plate are most com-
and beam.The concrete grips the shear
by making a span between supports up to
monly used in industrial buildings.
studs, transmittingthe shear forces through
about tw o metres (6ft), depending on the
the metal deckto the supporting structure.
depth of the grating.The choice of grating
The bond between the profile andthe con-
depends upon the spacing between the bars
crete is improved by the additional ribbing
and their depth. St eel grating is made by
is to usea composite deck made from deep
on its surface.The profiled sheet can be set
one of two processes: welding or pressing.
Steel composite floors An alternative to precast concrete floors profiled steel sheet wit h concrete poured on
either onto the top flange of the beam or
Lightly loaded small panels are manufactured
top. During construction,the profiled deck-
onto a plate projecting from the bottom
by welding flats and rods together. Larger
ing provides permanent formwork to the
flange.The second method reduces the
panels are made by a process that involves
concrete. Since the steel deck requires little
overall structural depth of the floor, with
pressing together rows of notched flat bars
or no temporar y propping when the con-
a consequent reduction in floor-to-floor
positioned at right angles to one another to
crete is cast, construction time is reduced
heights; it also stiffens the web of the beam,
form a grid.
in comparison to other cast-in-place tech-
increasing its performance.
niques.The steel deck and concrete perform structurally in a composite action where, in a
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336
Reuters Building, London, UK. Richard Rogers Part nership.
Steel mesh details 7. Steel mesh 8. Supporti ng steel structure, typically I-sections or channels 9. Fixing bolts
<1 ' 4
Vert ical section I:10. Composit e steel floor - section through slab
)
Vertical section I:IO. Composite steel floor - section through steel beam Finsbury Baracks, London, UK Architect:Arnold & Boston Architects
(7)
Vertical section I:5.Steel mesh deck and support
3-D detail of underside of steel mesh deck
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337
Details I. Soft wood fioor joists 2. Softwo od fioor plate
3. Loadbearing wall 4. Flo or boards or plywoo d/chipboard 5. St rutting to stiffen floor const r uction 6. Insulat ion
/ 3-D cut away detail of typi cal t imber floor support ed on masonry wall
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Timber floors are used typically with
butt-jointed or tongue-and-grooved.Alter-
either loadbearing masonry walls, usu-
natively,thicker boards are used, which have
and design of the floor. A recentdevelopment has been the
ally in cavity construction,or as part of a
the advantage of bracing the floor structure
introduction of'engineered joists' in timber
timber-framed structure.A typical floor
horizontally. Plywood sheet provides supe-
as an alternative to cut timber sections.They
for residential use, spanning up to around
rior stiffening action but its use makes access
make use of a combination of cut timber
3500mm might consist of softwood joists
to the void beneath more difficult. particu-
sections and timber composites that com-
supported at each end by galvanized metal
larly if the floor void is used for the passage
bine wood or wood fibre with adhesives.The
shoes or timber plates.Timber struts provide
of services. Additional stiffness is provided
main composite materials used in the joists
lateral stability and rigidity. Softwood boards
by herring-bone strutting set into the depth
are mainly LVL (laminated veneer lumber) or
aretypically used as decking which is either
of the floor joists at centres to suitthe span
OSB (oriented strand board
3-D cut away view of a typical timber famed building with timber fiooring
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339
a
Structure Floor structures 4: timber
3-D details of composite engineered timber and steel joists creatingfloor structure
Details I.Top / bottom cord in timber based mater ial
2.Vertical support in timber based mater ial 3. Steel connectors forming supporting web
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Typical joist hanger in masonry w all with engineered t imber jo ist
3-D details of composite engineered timber and st eel joists creating floor structure
Engineered joists are of two generic
with a timber deck and soffit lining attached,
types,those which resemble the form of a
as well as thermal insulation when used as
steel I-beam and thosewhich resemble open
panels for roof decks.
web trusses.The solid joist I-beam type is
An advantage of engineered joists is
made from top and bottom chords in timber
their ability t o form longer spansthan sawn
which are connected by a solid web made in
timber sections, with spans up to 12- 14
wood-based products such as LVL or 05B.
metres depending on the proprietary sys-
The open web types often have a series
tem used. The open web joists also have
ofV-shaped andtriangulated connectors
the advantage of being able to pass service
forming the equivalent of truss members
ductsand cables through the depth of the
with narrow timber flanges top and bottom
floor construction, which is an advant age in
connected by a vert ically set timber-based
mechanically ventilated buildings.These new
board material to form a structural web.
forms of floor construction are finding a use
These V-shaped connectors are made as
in commercial buildings as well as their use
proprietary products with fixing systems to
in the more obvious application in domestic
suit a factory-based manufacturing process
construction. Engineered joists also have
rather than for assembly in a small workshop.
the advantage of using less material than an
The idea of these engineered joists has been
equivalent solidtimber joist, which is also
taken further by joiningthem into prefab-
typically heavier than the engineered type.
ricated floor panels, also called 'cassettes'.
The lower moisture content of the materials
These are made in standard modules to
makes it less susceptible to moisture move-
suit reduced construction time on site, and
ment and reducing the risk of squeaking
where there is sufficient repetition to suit
noises associated wit h timber floors.
Typical tim ber floo r co nstructio n wit h mason r y str ucture .T imber boarding used for st iffness
prefabrication methods. Panels arrive on site
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341
Q;l CD 81 =r ®-
Verti cal section:Alternative fixing methods
Glass floors are used to enhance naturally lit spaces by allowing light to pass through to spaces below.The primary material used
Details to glass sheet floors
is typically either glass sheet or glass blocks.
I. Laminatedglass sheet, single glazed or outer layer of double glazed unit. 2. Silicone seal. 3. Stainless steel angle. 4. Spacer. S. Silicone bond. 6..Supporting str ucture.
W here glass sheet is used, laminated glass is set into a steel frame,giving it as much lightness and transparency as possible. W here glass blocks are used,they are set into a supporting frame of steel or concrete with
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reinforcing bars. Each block is individually supported,which has the effect of limiting the effects of lightness andtransparency. Economic spans for glass sheetare currently in widths of one metre, but panel sizes of 1200mm by 2600mm can be achieved, at significantly highercost.The glass is usually bedded within the frame on a flexible,
Vertical section: alt ernative fixing methods
Lerner Hall Student Center, Columbia Universit y, New York, USA. Architects: BernardTschumi / Gruzen Samton,Associated Architects.
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3-D deta il of glasspanel fioo r build up wit h stone fiooring and steel supporting str ucture
rubber-based material such as neoprene or EPDM , or alternatively bonded to the frame with silicone.This allows the supporting structure to move independently of the glass, as well as allowing each to move with thermal expansion. Junctions with the frame are closed with a silicone sealant. Sandblasting grooves intothe glass can provide transparency and slip resistance. In addition, a translucent laminated interlayer can be used to control views through the glass. Sheet glass fioor panels are currently restricted to relatively low loadings.Supporting structures can be in either steel or reinforced concrete. Ifthe supporting structure is constructedto the correct height and fall, ifused externally, then the laminated glass sheets can be bond3-D detail of glass panel fioor build up w it h sto ne fiooring and steel supporting structure
Educatori um, Utrecht Univer sit y,Holl and. A rchite cts: Rem Koolh aas. Office for Metropolitan Arch itecture .
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343
tructure 04 Floor structures 5: glass
3-D det ail of glassblock floor build up with ty pical steel suppo rti ng struct ure
Okanoyama Museum ofArt, Hyogo, Japan. Architects:Arata lsozaki & Associates
3-D detail of glassblock floor build up w it h t ypical steel supporting structure
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3-D detail of glass block floor build up with typical steel support ing structure
ed directly to it rather than setting them into
tions inthe frame becomes very high. Since
a steel sub-frame. Steel frames to support
joints in materials are usually expensive to
the glass useT-sections in order to provide a
form in relation to the cost of components,
bearing for the glass at the top, but avoid a
junctions are kept as simple as possible. For
bottom flange to the supporting beam that
this reason,frames are often made as cast-
would make the frame appear wider.
ings,where the material is poured in place
Glass blocks with textured or ribbed
to form a fram e. Cast iron, cast steel and
surfaces are often used as they have good
reinforced concrete are commonly used.An
slip resistance.This type of construction has
advantage of concrete isthat it can be cast
a high resistance to shock, and is capable
directly against glass blocks which become a
of very high loadings. Because each glass
permanent formwork. Reinforcingbars are
block requires support, the number of june-
laid in a grid in the joints between the blocks.
Details to glass block floor I, Glass blocks 2, Mort ar joints
3.Junction between adjacent concrete floor and frame to glass block floor sealed with rubberbased strip 4, Steel frame
3-D detail of glass block floor build up with typical steel support ing structure
I"1CH
345
Structure
Part elevation of concrete cantilever stair 3-D view of cantilevered concrete stair
Concrete stairs have the advantage of good
finish, anti-slip nosings are added.They can
used in a single project,and where a short-
fire resistance combined wit h the ability to
be recessed or surface fixed.Where the stair
er construction time is an important factor.
absorb impact sound. Concrete can be used
is exposedto view,the formwork into which
These stairs also assist in the construction
in conjunction with both steel and concrete
the concrete is cast has to be designed and
process itself by providing convenient
structures. Stairs can be of cast-in-place or
built carefully to reflect the quality of the fin-
access.This is particularly important if the
precast types, but the type used must be
ish demanded.
compatible with the overall type of construction used.
The junction at stair landings is often designed to create a single arris line across
design of the stair is complex, where the cost of precast staircases can be considerably more than the cast-in-place type.
the soffit.This allows handrails on different
In situ cast concrete In situ castconcrete stairs are made by settingsteel reinforcement into reusable
flights to be properly aligned, achieved by offsetting flights by a distance equal to one tread width.
Guardrails Guardrails on concrete stairs are most often pre-fabricated in parts,typically in
steel or timber formwork. A screed is added
steel, andthen grouted into slots or holes
afterwards to provide a smoother and more
drilled into the sides or treads of the stair.
exacting finish to the exposed surfaces.The screed can be used as a self-finish, when
Precast concrete Precast stairs are manufactured either as
Alternatively, t hey can be fixed to the side of the stair with steel brackets. Handrails in
used internally, but the dusty nature of con-
complete flights, sometimes with a landing
metal are either integral with the guardrails
crete walking surfaces often leads to the use
attached to one end,or as individual treads
or fixed to an adjacent wall.
of floor paint, or polishing the concrete, or
which are fixed together on site. Precast
insertingtreads in another material such as
stairs are used primarily where there is a
timber.W here the screed is used as a self-
large number of stairs of the same design
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346
Tadao Ando concrete ctaircase
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Precast stair with individually cast treads
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347
Strudure 0 Stairs 2: steel
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3-D view of steel stair
Vertical section 1:50 through treads
the stringeris critical in order that stringers
types can be finished in a variety of coatings
lighter in weight, allowing them to be prefab-
can be aligned neatlywhere they intersect at
from galvanizing to painting to polyester
ricated and delivered to site as completed
landings. Bolted or welded connections are
powder coating. Softer coatings such as
sections of flights and landings.They can be
madeto be sufficiently stiff so that the stair
PVDF are rarely used due to their poorer
lifted into place more easily than concrete
does not rattle or experience anysignificant
wearing qualities. In addition to visual consid-
stairs, but lackthe high fire resistance asso-
movement while in use. Depending on their
erations,the choice of finish is determined
ciated with that material.There are two
width, treads may need to have either their
by the required degree of durability and
generic types, with either treads as plates
edges folded to provide stiffness which can
appearance.
set between stringers, or with folded sheet
accommodate an additional finish such as
set between stringers. In addition, spiral
a decorative timber tread, or formed as a
stairs in cast iron and steel are available as
composite steel tray with a concrete fill. An
proprietary products in a range of standard
alternative method of stiffening treads isto
not often fixed to staircases before delivery
sizes.These comprise a central post to which
weld a vertical steel plate to their underside
to site in order to make the stair both easier
radiating treads are fixed.
to form aT-section.
to install andto make it easier to align the
Flat plate type
sheetand supporting it, either on stringers
ingwalls. Guardrails are usually finished
set at the sides or by a single central stringer
before delivery to site. If a paint finish is used
set beneath the plate.The inherent rigidity
the guardrail will at least be prepared and
Stairs can be formed by foldinga steel Stairs with plate set between stringers are made by bolting or weldingtreads
Guardrails Steel guardrails are prefabricated but are
guardrails with adjacent walkways or enclos-
formed from either smooth- or checker-
of the folded sheetallows a wide range of
primed before arriving on site where finish
plate. Stringers, which form the beams at the
economic solutions for the arrangement of
coats can be applied after its installation.
sides of the stair, are usually made from steel
the stringers. As with the fiat plate type,the
channel, which provides a straight vertical
assembly can be either bolted or welded,
face to which the treads can be fixed.The
and decorative inserts in other materials
position of the treads within the depth of
such as timber can be added. Both stair
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348
Steel stair,City Hall London
Details I , Guarding 2, Handrail 3. Steel stringer 4,Tread 5, Insert s,typically timber or concrete, set onto steel plate 6, Steel channel 7, Landing in steel plate 8, Steel plate deck
9, RHS box section 10, Balustrade I I, Folded steel plate t o form continuous tread and risers 12, One stringer wit h projecting arms to support treads/ risers or two stringer sets near edges of stair
School of Decorative Crafts, Limoges France,Architect: Labfac / Finn Gepel. Nicolas Michelin
Ted Baker Building, London, UK, Architect: Matthew Priestman Architects
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MCH
349
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House in Cappeco,Viana de Castelo, Architect: [oao Ferriera Alves
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Vertical section I:10& I:50 through stair
An advantage of timber staircases isthat
House West London, UK. Architect:Seth Stein Archit ects
correct alignment of treads.Trimmer beams
they can be integrated easily into adjacent
are sometimes added at the top and bot-
timber construction and can be modified
tom of t he staircase to stabi lise the staircase
easily on site in a way that isvery difficu lt to
and provide fixing pointsto the adjacent
achieve in an equivalent steel or concrete
floors, which are typically also of timber
construction.Timber stairs consist of string-
construction.An alternative approach isto
ers or carriages, which support the stair, to
use heavytimber sections to form staircases
which treads and risers are fixed. Several
t hat resemble those in steel.Steel brackets
carriages may be positioned between string-
that are bolted into the timber sections
ers as loading demands.The stair isgenerally
connect the stringers and separate treads
delivered to site as a complete structure
together.They can easily accommodate steel
secured with timber wedges,which avoids
guardrailswhich are bolted through the large
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the need for visible fixings. Relatively small
stringersections.Timber guardrails follow the
piecesof timber are used.The thin timber
traditional use of balusters at close centres,
sections are prone to shrinkage and creep
typically set IOOmm apart.The lack of large
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unless they are locked together. Because
structural members intimber stairs makes
timber stairs have poor fire resistance,
the use of balusters at wider centres,as used
they are often restricted to residential use.
in steel or concrete construction, less suit-
Treads and risers are fixed togethe r with
able.Timber connectionsare more fragi le
tongue-and-groove (or rabbeted) joints that
than those in stee l; they must also accom-
provide a tight fit and avoid creaking when
modate more movement due to moisture.
t he stair is in use. Both treads and risers are
Balusters at close centres allow imposed
fitted into rebated slots cut into the string-
loads on the guardrai lto be spread evenly
ers where they are wedged to provide the
along the length of the stair stringers.
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350
3-DView of timber stair
Details I . Handrail
2. Balustrades 3.T imber beam 4.Tread
5. Carriage
6.W edge 7. Bracket
8.W all 9. Riser I O. N ewel post I I. Trimmer joist
Vertical section I: I0 t hrough handrail
3-D view of timber stair
Handrail detail
Verti cal section
3-D view of timb er stair
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3-D view of glassstair Vertical section I:50
the bedding provides both a cushion and a
without additional vertical support.A 12mm
tage of transparency. allowing light to pen-
Stairs with glass treads have the advan-
method of ensuring that the glass is evenly
thick sheet istypically used.A handrail can
etrate down the stair enclosure.The glass
supported along all the edges and is fixed
be added by introducing a rebate into the
used is usually a thick laminated glass which
level. An additional weather seal is used on
handrail section and setting it directly onto
can be made of two sheets of float glass
the sides of the glass between the glass and
the top of the glass guardrail. An alternative
with a thin interlayer. or toughened glass with
frame. if the stair is to be used in external
method is to form a guardrail from steel
a more robust interlayerthat stays in place if
conditions.Treads often have a surface treat-
posts that support a handrail. wit h laminated
the two toughened sheets are broken. Glass
ment to provide slip resistance. Sandblasting.
or toughened glass sheets used as infill pan-
treads can be supported either within a steel
etching or the addition of a carborundum
els.The glass can be fixed with clamps or be
tray which provides support on all edges. or
coating. typically in strips, is used for this
bolt-fixed backto the posts. Glass sheets
be two edge supported.An alternative isto
purpose.
are set with a vertical gap of around IOmm
bolt fix the glass using techniques taken from their primary application in glazed walls. This method allowsthe stairto be suspended
Guardrails All-glass, or structurally glazed. balus-
from cables, a technique still in the early
trades can be constructed with sheets of
stages of use.The tread assemblies are then
toughened or laminated glass and used with
usually supported by steel stringers. though
a stair built in another material.They com-
concrete can also be used.
prise sheets of toughened or laminated glass fixed at floor level with either a clamped
Where glass treads are set within a steel
plate secured by bolts or by bolt fixings
supporting tray, the laminated glass sheet is
directly through the glass.The glass must be
set directly onto a silicone-based bedding.
sufficiently strong and rigid to span vertically
In addition to holdingthe glass in place.
MCH
352
between them which is filled with a translucent or transparentsilicone seal.
Details I, Glass balustrade fixed at base 2, Stainless steel handrail 3. Steel stringer 4, Glass treads,typicallysandblasted to provide friction S, Steel tube support frame 6" Steel angle 7, Glass landing in steel plate
Glass stair in Apple store, Regents Street London, UK, Architect: Bohlin Cywi nskiJackson
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353
ENVIRONMENT Energy and the building envelope Double skin facades Environmental studies for envelopes Analysis for design I Solar radiation 2 Daylight 3 Embodied energy Passive design I Natural ventilation 2 Solar shading and Daylight controls 3 Solar power 4 Solar heating Low energy material systems I Straw bales and hemp 2 Rammed earth, cob and adobe bricks 3 Green oak and bamboo 4 Green walls Active design I Liquid based heating/cooling systems 2 Mechanical heating/cooling systems 3 Electrical lighting 4 Fuel and water supply Support services I Sanitation and drainage 2 Fire control 3 Maintenance and cleaning 4 Lifts
MCH
355
Environment 05 Energy and the building envelope
Studies for a moveable shading system
Rendered studiesof shading devices at different times of day / year
This chapter discusses environmental design
the idea of 'energy' is considered important
in terms of passive and active methods
today and detailing becomes more complex
that can be used to modify environmental
in response to these changing priorities.
conditions within a building.Active controls
Cultural Centre at Noumea. Architect: Renzo Piano Building Workshop.
. --MCH
356
Until recently. the expression of struc-
are provided mostly by mechanical ventila-
ture and construction (particularly of joints)
tion systems that are usedto heat, cool and
was considered one of the primary archi-
vent ilat e spaces. Passive controls can be
tectural intentions in cladding design.This
provided by natural ventilation,by the useof
situation is slowly changing. More buildings
the building fabric asa thermal mass to slow
are clad externally with insulation, where the
down the rate of heating and cooling, and by
rainscreen panels that conceal it from view
solar shading or passive heating.A combina-
have both a waterproofing and a decorative
tion of these methods helps to reducethe
function. Rainscreens are a recent develop-
energyconsumed by buildings in use.
ment that allows a simplified approach to be taken to movements in the primary support-
Fifteen years ago, combinations of struc-
ing structure of the building.A continuous,
ture and cladding were generally limited to
uninterrupted appearance can be achieved
the use of materials that were constructed
with a consistent gap between panels that
either from the same base material (either
extend across movement joints in the build-
steel, concrete or timber) or from materi-
ing structure. Both movement joints and
als having compatible amounts ofthermal
breaks in the construction need not be
movement.Today, the useofthe thermal
'registered' on the facade.Joints can be reg-
mass of the structure, and materials with low
istered on the facade but they serve only as
embodied energyhave led to a much wider
a decorative device.The real movement joint
range of structure/cladding combinations.
concealed behindthe panel can be achieved.
While thermal and structural movement was
A notable example is the Cultural Centre
the main issue in detailing fifteen years ago,
at Noumea, designed by the Renzo Piano
Solar radiation incident on a building's facades. Pr• •• u ~ • •
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CFD analysis of air movementaround a facade.
Building Workshop. In contrast, agreed infor-
form more efficiently in generating electricity
mation about levels of embodied energy in
when inclined towardsthe sun.The first
typical forms of building construction has yet
large photovoltaic panel installation is at the
to become available. However, various guides
University of Northumbria in England.The
are available which help to steer designers
output of electrical power fiuctuates with
towards suitable material selection.
changing weather conditions. For this reason
Analysis of solargain through a facade.
the building is supplemented by a convenPhotovoltaic cells are used to generate
tional electricity supply. Operating periods
electricityfrom solar radiation (sunlight) .The
range from fifteen hours per day in May
power generated is then used inside the
to eight hours in January. The installation is
building. Electricity is generated in panels of
expected to pay backthe energy used in the
semi-conductordevices containing a glass
manufacture of the cells within three years,
substrate coated with tin oxide, forming
then produce electricity for a further twenty
a transparentelectrode, which is covered
years.The electricity generated is expected
with layers of silicon together with a coat
to meet 50% of the building's needs in sum-
of aluminium film which forms the other
mer and 10% in winter,averaging around
electrode. Particles of ultraviolet light called
30%over a year. The cost of generating elec-
photons interact with electrons in the semi-
tri city through photovoltaic means is about
conductor to convert sunlight into direct
four times the current commercial rate.
current electricity. Panels are orientated towards the path of the sun.The photovoltaic process has the advantage of requiring no moving parts, requires no fuel and needs relatively little maintenance. Photovoltaic
University of Northumbria,UK.
panels can be used as semi-transparent panels in glazed wall systems, though they per-
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nvironment 05 Double skin facades
Twin wall facades An important development in facade
3-Dviewof corner clampeddouble skinned facade system
which increases the amount of electrical
or alternatively metal flaps or louvres at floor
lighting required internally. Layered facades
level that are operated mechanically to admit
technology has been the recent introduction
separate out functions of waterproofing, solar
air at different times of day and at different
of double skin facades. Double wall facades
control and vent ilat ion in different configu-
times of year.This latter method provides
are a solution to increasing requirements for
rations. In double wall facades these have
a more controlled method of regulating air
natural ventilation, increasing daylighting and
become two generic types:thick walls and
intake into the void between the two skins,
the useof thermal mass for night time cool-
thin walls.
ing, providingenergy savings of up to 50% for the energy used in the mechanical ventilation. External shading is important in buildings
but is considerably more expensive than the open joint method. Once air has entered the
Thick walls In thick double walls, an outer layer com-
void its wind speed drops dramatically, allowing the inner glazed wall to have opening
with glazed facades where there is a risk of
prises a single skin of glass, typically a single
windows to introduce fresh air.This method
overheating inside the building. Fixed shading
glazed bolt fixed glazed wall.This is separated
is particularly useful in taller buildings over
systems are considerably cheaperthan those
from the inner wall by a gap of between
three storeys, where the wind speed is often
wit h moveable screens or louvres, but they
750mm and IOOOmm.The wide cavity is
too highto allow windows to be opened
cannot move in responseto the path of the
required to provide adequate amounts
safely, particularly in office buildings and pub-
sun, or to changing weather conditions and
of ventilation.The inner skin istypically a
lic buildings. A walkway is set into the void,
different times of year. Internal shading does
standard double glazed curtain wall system
usually at the same level as the internal floor
not perform as well, as mentioned in the fol-
using either stick or unitised systems, with
to provide easy access to it and ensure that
lowing sections. In double skin facades the
opening windows. Because the outer wall is
the walkway does not obscure views out of
solar shading is installed in the void between
protecting the inner wall from windblown
the building.The walkway allows the glass sur-
inner and outer skins, where the blinds are
rain, materials other than metal and glass
faces facing into the void to be cleaned and
better protected. Conventional single layer
can be used to form the inner wall.Fresh
maintained easily. Depending on the height of
glazed wallstend to introduce conflicting
air is allowed to pass through the outer wall
the facade,the natural ventilation provided
performance requirements into a single layer.
into the zone between the two skins.This is
by this configuration uses external wind
Solarcontrol films or layers have the effect of
achieved either by having open jointed,or
pressure to provide fresh air into the void. It
reducing the transparency of external walls,
partially open joints in the outer glazed wall,
usesthe stack effectto allow the heat gained
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358
J_
-t.-
o ~.
Details I . Outer skin of sealed bolt fixed glazing 2. Inner skin of openable aluminium framed doors and fixed lights 3. Retractable blind 4. Floor construction 5. Zone for air extraction to mechanical ventilation 6. Plants
CD
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0)
Elevat ion I :25 Vertical section I :25
ill
w
ill
.J.
1.
1.
Plan 1:25
3-D view of twin wall from inside
3-D view of t win w all cavity
MC H
359
Environment 05 Double skin facades
3-D section cut through double skinsystem with openablescreen
I:50 Plans and elevations :Thick wall with ventilated outer screen II
II
Jl
Jl
F "
l
1 I I I I I
/ /
Plan view of twin wall with openable screen
J.
·u
--- - -- - 1- - - - - - - - - + - I
I
I
-1
II
View of vert ical sectionthrough stepped twin wall facade system
.~~
I:50 Plans and elevation :Thin wall with out
·11
sealed glazed unit
Details I. Outer skin of sealed bolt fixed glazing 2. Inner skin of openable aluminium framed doors and fixed light s
Details I. Outer skin of sealed bolt fixed glazing 2. Inner skin of openable aluminium framed doors and fixed light s 3. Retractable blind 4. Floor construction 5. Zone for air extraction to mechanical ventilation 6. Plants
Q
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s:
- CD
3. Retractable blind 4. Floor construction 5. Zone for air extraction to mechanical vent ilation 6. Plants
:110
'U'n.
II 1
·r
Vertical Section I:25 through thick twin wall system
MC H
360
(i)
o
I
I
II
Vertical Section I :20 and 3-D viewthrough double skinned facade withplant incavity
within the void, in warm weather; to escape
ditional blinds and other solar devices and
to the outside. In wint er;where solar gain is
can provide very efficient shading to inter ior
a much less significant issue, in open jointed
spaces. In addition t o thisthey can provide
inside of the building is drawn t hrough into
methods of ventilat ion the outer skin can
sound attenuation as well as providing poten-
the facade at floor level or in the void below
suffer from cold air being allowed to enter
tial crops or food growing areas in buildings.
floor level and is drawn up through the
louvres allows the quantity and frequency of
In wint er; warm air extracted from the
external wall to reduce the amount of heat
the void, which can act as a winter 'buffer zone'.The method of using metal flaps and
air is then ejected at the top of the panel.
Thin wal ls Thin wall facades comprisetwo skins
loss through it. W hen air is drawn through the facade from inside the building,the wall
fresh air entering the void to be more closely
of glass set closely together;with a cavity in
becomes an integral part of the mechanical
controlled.This helps to regulate the temper-
the region of IOOmm wide. The cavity is
vent ilation system for the building.The air
ature of air passing through the inner wall, by
mechanically ventilat ed, allowing it to be con-
is drawn thro ugha heat exchanger to be
ventilation or by opening windows.Air in the
siderably smaller in depth than the naturally
used in heatingthe space in cooler months,
void between the two skins will be warmed
ventilat ed thick wall design.Air can be drawn
or is ejected from the building throughthe
in winter by heat transmitted through the
up through the cavity from outside or from
mechanical venti lation system. In summer; air
facade as well as any incident solargains. The
inside.Air drawn from outside needs to be
drawn up the cavity from inside the building
cavity within a double skinned facade acts in
relatively free of dust and pollution, since this
passes over the solar shading blinds, which
a similar way to that of a greenhouse.This
makes the cavity dirt y quite quickly. In this
are dropped down in place to provide
area becomes ideal for the growth of many
system, the air drawn thro ughthe facade is
solar shading.The heat from the blinds, as
plants.The plant s can not only enhance the
separat e from the mechanical ventilation for
a result of the solar energy, is drawn away
appearance of the facade but also enhance
the building.The inner skin has a series of
and is ejected from the buildingthro ugh the
the environmental benefits of the double
opening doors t o allow access into the cavity
mechanical vent ilation system.
skin system. Double skins help insulat e the
for cleaning and maintenance. Blinds are usu-
W hen the air into the cavity is provided
building, absorbing the heat of the sun during
allyset into the void in order to provide solar
from inside,the facade is completely sealed,
summer and retaining warmth during winter.
shading. Solar energyabsorbed by the blinds
and requires only occasional access t o the
Plants, it has been shown,are more efficient
is radiated into the cavity where it is drawn
void for cleaning and maintenance.
in contro llingthese environments than tra-
away by air rising in the cavity.The warmed
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nvrronment 0 Environmental studies for envelopes
W ind rose for UK site
Shading pro file fo r building facade .~
In addition to the development of design
performance has been altered.The main
drawings for tender;together with a specifi-
criteria that are checked are air temperature,
In turn the thermal conductivity of a
cation, architectural requirements and gen-
humidity levels inside the building or in semi-
material is the amount of heat in Watts pass-
eral technical requirements,the drawings
external spaces such as atriums, ventilation
ingthrough a material having a surface of
and specification must be informed by both
levels and daylighting, including its effect on
Im2 andthickness of I metre under a tem-
visual mock-ups and by an environmental
electrical lighting. If one of these is changed
perature differential of 1°C. Materials which
study. In some projectsthe environmental
as a result of a particular design require-
are high insulators have a low lambda value, which is expressed in W /m2 K.
study will be undertaken after tender; when
ment, such as the use of single glazing in a
a better idea of what can be afforded by the
semi-external facade, for example,then the
budget becomes clear. Whether the study is
accompanying effect of increased internal
around 0.25W/m2 K, while glazed walls in
conducted before or after the tender proc-
temperature must be weighed against the
sealed double glazed units, with a low emis-
ess' the information required from the study
benefit of natural ventilation in warmer
sivity (lowe) coating can reach U-values as
remains unchanged.
months.
low as 2.0W /m2 K, though some units are
Small scale environmental studies are
A significant part of an air temperature
Expected U-values for opaque walls are
considered to reach even lower levels with
usually undertaken as small, specific studies,
study is a study of the heat losses and heat
argon filling in the sealed cavity of the double
usually done as a series of calculations for
gains through a facade. U-value calculations
glazed unit. For glazed facades, andtranslu-
different conditions or different times of day
are used primarily on opaque facades, or
cent plastic cladding facades, U-values are
or year. Bigger scale studies are structured
those wit h a low proportion of glazing.A
rather less useful and solar energy passing
as models, where a largeamount of data
U-value is a measure of thermal transmit-
through the facade produces significant heat
is added for different times of day, times of
tance of a facade construction, with the high-
gains which do not form part of the U-value
year;or extremes of temperature, for exam-
er levels of thermal insulation having lower
calculation.The solar energy is measured as
ple,to seewhat happens when one of the
U-values.The U-value is the total insulation
a 'g' value.Typical' g' values of double glazed
parameters is changed.The preparation of
value of the various materials forming the
units are between around 55% and 80%,
a model takes much longerthan a specific
construction.The formula for their calcula-
depending on the coatings and films used.
'desktop' study, and is considerably more
tion is as follows:
Although g-values are useful for calculations,
expensive, but provides a means of interacting wit h the study, rather than examining a
U
in practicearchitects and facade designers
=
_1 + _1_ + etc (W/m2 K)
K,
series of specific 'snapshots' taken for par-
K2
ticular'events' in the building facade.
tend to work with a 'shading coefficient' which is often the basis for the design of mechanical vent ilat ion systems wit hin build-
Environmental studies are usually con-
=the insulat ion value of a material
ings.A shading coefficient for a facade, or
ducted on facades which deviate from
where k
systems for which performance data is
measured in term s of its thermal conductiv-
energy incident on the facade in glazed
readily available. As soon as one of the
ity (symbol lambda) divided by the thickness
areas.The shading for a glazed facade will
parameters for thermal comfort in the build-
of the material (L) expressed in metres.The
be provided, effectively, by the opaque span-
ing is changed, the other criteria then need
k value is expressed by the formula
drel zone concealing the floor construction (unless the facade is continuously glazed)
to be checked to seeto what extent their K
MCH
362
area of facade, is the percentage of solar
=
!l. (W/m2 K) L
CFD analysis of air movement around a building facade
and any external shading devices. Shading
demanding or extreme conditions expe-
devices will provide different amount s of
rienced by the facade.This might be done
ing watertight and secure for occupants.
shading at different times of the day, so the
in summer when, for example, it is hot and
The thermal mass of the building absorbs
overall shading coefficient is not a straight-
humid at 45° outside,while internal condi-
and releases this heat energy over a 24 hour
forward value to obtain, and forms part of
tions are air conditioned at 18°. It is essential
period in order to reduce the rate at which
an environmental study aimed at reducing
to know where the dew point will occur to
the temperature inside the building would
pass into the building at night while remain-
the amount of energy needed to cool the
see if condensat ion forming at the dew point
rise during the day.This reduces the amount
building and air provided by mechanical
will causeanydamage to the construction,
of energy needed in mechanical cooling
ventilation.A shading coefficient of 50% is
and whether vapour barriers are needed
systems, and can even allow such mechani-
not uncommon for large glazed facades with
in particular locations, or whether it is bet-
cal systems to be omitted altogether in the
shading devices that allow clear views out but
t er to allow parts of the construction to be
building design.The air temperature inside
provide some solar protection without signifi-
vent ilat ed t o either the inside or the outside.
the building is linkedto vent ilat ion rates,
cantly reducing daylight into the building.
W hile data for established forms of construc-
which is expressed as 'air changes per hour',
tion is usually easily available,and is used by
which can vary from one air change / hour
to the effects of natural ventilation, increased
manufacturers, unusual designs or significant
for small spaces with a low occupancyt o 4-6
levels of natural daylighting and the use of
variat ions from established facade systems
air changes / hour for public buildings and
thermal mass for night time cooling.Air
will need t o be checked from first principles.
spaces where there is a high occupancy.
Environmental studies are often linked
temperatures within buildings are kept at
Natural ventilat ion is anot her central
Computational Fluid Dynamics (CFD)
between around 18° and 25°,with the sur-
issue in many facade-based environmental
analysis can be usedto evaluate air flows
facetemperature of facades being a few
studies,where buildings are reducing the
around buildings and highlight areas of high
degrees either side of this t emperature for
energy consumptio n in heating, cooling and
windspeed or pressurethat may have an
the internal face. Isotherm diagrams are
mechanical ventilation by increasing the pro-
adverse effect on pedestrian comfort or
used to investigate and check variations of
vision for natural vent ilation. Facade design
cladding performance.
temperature across facade systems, and
plays a central role in this area by providing
Understanding air movement around a
these also serve to detect and check thermal
systems that can allow fresh air t o enter
facade enables cladding systems to be devel-
bridges across facades. Isotherm diagrams are
through the facade without the accompany-
oped that can withstand wind pressures on
also used in conjunction wit h thermal calcula-
ing wind gusts, noise and dust experienced
the site. It also helps with the placement of
tions or thermal models of a building, includ-
in t he built environment.The effect of heat
air intakes and extracts to maximise their
ing its facade.
gains during the day can be reduced by
efficiency.
Humidity levels are significant in the
allowing the building structure and fabric to
CFD analysis is often used as preliminary
transition from inside to outside, particularly
absorb heat energy mainly from solar energy,
study that can lead on to wind tunnel test-
when linked to extremes of air temperature.
external temperature and the heat generated
ing as it helps to highlight key areas for more
The relative humidity inside buildings is set
by building users.At night,the building fabric
detailed analysis.
in the regio n of between 30% and 70%
is cooled again by allowing the cooler night
depending on the internal air temperature.
air from outsidet o be drawn through the
Dew point diagrams are used to determine
building structure to cool down the building
where condensation will occur for the most
fabric. The facade is designed to allow air to
MCH
363
a
nvironment Environmental studies for envelopes
Solar radiation distribution for complex facade
Decisions made early in the design process
these opportunities for analysis, it allows
have considerable influence over the envi-
them to keep step with the specific envi-
ronmental performance of the completed
ronmental demands of their building.This
building. Designers need no longer rely on
helps the design team keepthe overall
'rules of thumb' to create energy efficient
project design in balance rather than hav-
buildings during the early stages of design.
ingto accept 'features' being added to the
The use of computer software can also
final design as consultants try to alleviate
allow designers to be more independent of
problems caused by a lackof environmental
specialist consultants during the early stages
input at the early stages. Digital analysis also
CFD analysisto understand air flowsaround shad-
of design without ignoring the essential
allows the design team to understand the
ing louvres
issues of environmental design. Specialist
performance of their building wit hout having
consultants too often become involved in
to invest significant ly in mock-ups or time
a building design only after the conceptual
consuming calculations undertaken by hand.
stage of the design process is complete. Computer software has developedto
Solaraccessanalysisto assess the impact of bespoke shading system
MCH
364
One of the major benefits of computer based analysis isthat it can be used
the point that many 3D CAD design applica-
to inform design decisions at all stages of
tions have some form of environmental anal-
the design process. Data is displayed in a
ysis tool s built into them. Most applications
graphic mannerthat is easy to understand
will allow the designer to project shadows
and interpret, and also aids discussion with
both onto, and created by, the building being
other project consultants. At the earliest
designed. Some more advanced software
stages of a project. environmental analysis
applications will provide an analysis of solar
can help inform decisions about the orienta-
gain, calculate approximate daylight levels
tion and specific geometry ofthe external
and give information about the thermal
envelope.Analysis can be carried out on a
properties and embodied energy of con-
digital model of the 'empty' sit e to help the
struction materials.
designers to build up a picture of the micro-
If designers both useand respond to
climate they are dealing with and ensure that
Shadowtracking for urban site
appropriate design responses are formulated at the earliest stages of the project. Information about annual sunpaths,temperature ranges, humidity and prevailing winds can be used to identify key issuesthat need to be addressed during schematic design.This analysis becomes even more important when dealing with projects in parts of the world unfamiliar to some in the design team and will help identify how design solutions which are considered to be 'standard' may need to be modified to meet specific environmental conditions.As the design process develops and more information can be input into the software programme, more detailed environmental analysis can be carried out on the project.This analysis can help inform decisions about geometry optimisatio n, window placement and shading design.Throughout the design process the impact of design decisions can be analysed and their conse-
Analysis of the impact of shading systemsonsolar radiation distribution on buildingfacade.
quences evaluated.This process is conducive to an iterative design process where many options are proposed, analysed and modified and analysed again. Because the resulting data is displayed in such a graphical way it is easy t o compare the results to identify the most successful solutions to the design brief.
MCH
365
nVlronment 05 Analysis for design I: solar radiation
A bove: O verlaying shadow proj ections fo r on e day helps evaluat e how the building's shadow t racks across t he sit e.
45 latitude
25 latitu de
65 lat itude
/
f.
(
... e - ..--
Compariso n of sunpath s at different glo bal latitudes and the effect on shadow projectio ns
MCH
366
Left:Analysis of the overshadowing effectof surrounding buildingson a proposedfacadevolume. Areas of the facade closestto theground are subject to much lessdirect sunlight Above:Analysisof the overshadowing effect of a building's exoskeletal structure on the facade glazing.
Sunpath An awareness of how the sun moves
allowsthe designer to visualise the overshadowing effect of surrounding buildings, as
Overshadowing In urban areas, the effect of overshadow-
around a building at different t imes of the
well as the extent to which the proposed
ing from adjacent buildings may have a sig-
year can assist wit h the design of solar shad-
building will,in turn, overshadow its neigh-
nificant impact on certain aspects of design.
ing for a building. In most situations the spe-
bours.This is particularly important for urban
A reas of the facade that are in shadow
cific design aim would be to exclude some
sit es where maintaining rights of light may be
for most of the day will not require the
of t he effects of t he sun during the sum-
a significant aspect influencing t he building's
same shading design as areas that are more
mer months, when solar gain is at it s most
design.
exposed. Traditio nal analysis techniques
Mapping how building shadows t rack
would treat all areas of a facade in the same
behind the facade to enjoy the effects of
across the site t hroughout the day helps
manner. based on 'wor st case' environmen-
solar gain during the winter to take advan-
wit h t he design of outside space. Cafe ter-
tal condit ions. Digital analysis allows the
tage of its warmt h.
races can be sit ed in areas which attract t he
designer to take overshadowing into account
sun and external landscape features can be
to produce optimised shading solutions.
way of assisting this understanding and most
positioned based on their planting require-
This type of analysis can also be applied to
3D CAD design software will allow the user
ments
smaller facade modulesto assess whet her
intense, but potentially to allow some spaces
Sunpath diagrams offer the most visual
to evaluate t he sun's position in real t ime for
Sun pat h analysis can help to ident ify
overhangs, projections or other envelope
any t ime of day at any locat ion in the world.
problems with reflections from the building's
details will have an overshadowing effect.
facade.This is more of a problem in built up
Shadow projection The sunpath features in 3D CAD design
areas since the glare from the sun on occupant s of surrounding buildings can cause sig-
Solar exposure Digital environmental analysis can help
software also enable t he userto evaluate
nificantdiscomfort. Digital analysis can help
t o identify areas of high solar exposure over
shadows falling across the model.This allows
to alleviat e these concerns by projecting the
a building and assist wit h the placement
real t ime analysis of the sun's penetration
path of building reflections t hroughout the
of solar panels on t he facade.With more
into buildings, aiding the designers wit h the
year.
detailed analysis it is possible to calculate
placement of windows aswell as the design
how much energy these solar panels can
of the electrical lighting.This analysis also
generate over t he course of a year.
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367
Environment 05 Analysis for design I: solar radiation
Above and left:Solar access analysisfor an office space highlights which areas are most exposed to direct sunlight across the course of a year
Solar gain Solar gain can be defined as th e increase
Environment al digital modelling can help to
the absorption of th e sun's energy by the
indicate the distribution of solar radiation
building fabric. In most sit uat ions it is neces-
across th e facades of a building and build up
sary t o min imise solar gains, especially during
a picture of w hich areas inside the building
t he summer,t hough in coo ler climat es solar
are particularly at risk from overheat ing.This
gain is somet imes enco uraged as a means of
info rmat ion can be used t o help inform deci-
reducing inte rnal heat ing loads. In buildings
sio ns abo ut wi ndow placement and mate rial
w here nat ur al venti lat ion systems are being
systems.
368
T here are a numb er of w ays of control-
solar gains match nat ural cooling capacity
ling t he effects of solar gain. Solar control
to ensure th at spaces in th e building do not
glazing can help t o reduce t he amou nt of
overheat.
so lar t ransmittance t hrough w indows and
The sun is at its stro ngest t owards the
MC H
high pro po rtion of it s energy t o t he cladding.
in t emperature of an intern al space due t o
considered it is important t o ensure t hat
Above:Solar radiation distribution across a building facade during summer (top), mid season and winter (bottom)
facade at a more direct angle, t ransferring a
glazed facades.Shading systems are an effec-
midd le of th e day w hen it is also at it s high-
t ive means of cont ro lling so lar gain since
est.At th is po int th e sun is incident on verti -
the y limit t he amo unt of solar radiat ion t hat
cal facades at quite a steep angle, depend-
penet rates the facade. Exte rn al shading is
ing on the t ime of year and geographical
far more efficient at cont ro lling solar gain
location , so th e proporti on of heat energy
th an intern al shading, but requires cleaning
transferred is relatively low. Roofs and at ria,
and maintenance, as w ell as being able t o be
w hich face t he sun more directly,are par-
rem oved in t he event of facade com ponents
t icularly vulnerable to solar gain during t his
being replaced. Careful choice of ot her clad-
period of th e day. Eit her side of it s peak t he
ding mat erials w ill also help min imise heat
sun's strength reduces but is incident on th e
transmittance th rou gh t he facade.
Above:Te sting the effectiveness of recessed glazing t o minimise so lar gain. Recesses get deeper from right to less and provide greate r shading to the window pane
Right Testing th e effectiveness of a complex shading system.
In hot climates it may not always be pos-
irrigation requirements. Wi thin buildings, solar exposure analysis
sible to control solar gain by passive means.
solar gain since the solar energy has already passed through the facade and is radiated
In this case mechanical ventilation systems
can help to understand how sunlight will
and convected back into the room having
will be needed to provide additional cool-
penetrate through facades. It provides a
been absorbed by the internal shades.
ing inside the building. By analysing the peak
more quantitative measure of solar access
annual radiation values for the facades it is
which may be of use when designing internal
guidelinessuggest horizontal shading devices
possible to design mechanical systems to
fit outs,helping to identify areas where com-
are generally effective on south facing
cope with the effects of overheating. In this
puter screens or sensitive equipment should
facadesto deal with high angle sun,whilst
situation it is still beneficial to use passive
be placed, for example. In conjunction with
vertically set systems on the eastand west
solarcontrol systems as this will reduce
computer software generated renders the
facades are generally efficient at dealing with
the average energyuseof the mechanical
study can help to build up a more complete
low angle sun.
systems
picture of how sunlight penetrates the build-
Sunlight penet rat ion Solar exposure analysis identifiesthe
In the design of buildings it is not always possible to follow these guidelines. but
ing.
number of hours facade elements are in
In the northern hemisphere typical
detailed digital analysis can help designers
Shading design The use of external shading can signifi-
derive more specific systems suited to both the building'sgeometry and location. It erative design techniques help t o assess
direct sun.Wh en read in conjunction with an
cantly reduce the amount of energy needed
analysis of solar radiation distribut ion. solar
to cool buildings in summer months in either
the effectiveness of different shading systems.
exposure analysis can help create a more
temperate climates or hot climates. External
This allows shading systems that may be
complet e picture of how the sun is impact-
shading prevents solar energy from passing
considered to be more visually unconven-
ing on solar gain across the facades.
through a facade by absorbing,then radiat-
t ional, but very effective,to be developed
ing and convecting solar energy outside
with confidence that they will function effec-
carried out for the landscape surrounding
the building envelope. In contrast, internal
tively.
buildings in order t o inform decisions about
shading has much less effect in contro lling
Solar exposure analysis can also be
hard landscape design, planting schemes. and
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369
nvuonment
a
Analysis for design 2: daylight
Left:Daylight studies for an office floor.Thisanalysis evaluated the effect of reducing the proposed windowopenings by half to reduce theimpact of solar gain onthespace.The analysis concluded that daylight levels were still adequate with smaller openings.
Above left: Computer rendering can help identifY lighting patternswithin a space and understand how external shading systems affect internal lighting levels.
Levels of daylighting in buildings have
Analysis method
increased in recent years in building types that consume a high level of energy in
requires considerable data input to achieve
electrical lighting, mainly office buildings.An
accurat e results. Changes in minor elements
increase in daylighting,accompanied by a
of the design such as internal finishes can
cont rol of glare and solar energy from exter-
have a significant effect on the daylight factor
nal shading has led to a reduction in the
within a given space.
energy used in electrical lighting, particularly near the glazed walls.
370
Computer rendering can be used as a simpler alternative to digital analysis if quan-
Daylighting levels are expressed as a
tative results are not important.Care must
daylighttransmission factor, measured in
be t aken when t reating rendered images as
term s ofthe percentage of daylight passing
accurate representations of actual lighting
through the glazed facade. Daylight transmis-
conditions as what appears dark in a given
sion factors of 70% to 80% are common
image may actually be adequate in a wo rk-
in double glazed units. For daylighting levels
ing environment.W hen used in comparative
in buildings and their accompanying levels
analysis, rendered images can help to assess
of electrical light t o either supplement this
the quality of light within a space over the
or provide electrical lightingduring hours
course of a year.
of darkness, the amount of light required is
MCH
The calculation of internal daylight levels
If quantative daylight analysis is under-
defined for different tasks. Lighting levels are
taken it is essential t o construct the digital
expressed in terms of lux,wit h office spaces
model as accurately as possible wit h regard
having 250 lux, depending on how detailed
to window openings, floor and ceiling pro-
the work needsto be, and how the lighting
files and proposed furniture.
is distributed between general lighting from
Analysis is typically carried out on the
the ceiling, and t ask lighting usually provided
working plane of the room,typically 700mm
on desks, which can give up t o 400 lux.
above floor level, as this is where light levels
Above: By comparingrendered views it is possible to build up a picture of how light levels fluctuate throughout the day. Right Daylight analysisto quantify the effectof shading louvres. Below right: Rendered study looking at the effects of shading louvres.
have most impact on the occupants.Analysing a space in section is also beneficial as it can highlight areas of part icularly high contrast between light and dark spaces.
Daylight vs solar gain An environmental study can investigat e what daylighting levels are provided by a facade and suggest ways of modifying the design to balance daylight with heat gains and energy losses. When designing shading systems a balance needs to be struck between providing an appropriate shading response and maintaining natural light levels within the building. In climat es where light levels outside the building are particularly high it is necesssary to reducethe amount of open areaon the facade to reduce glare and create comfortable wor king conditions for the occupants. In this sit uation shading elements can help to reduce the overall transparency of the facade.
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Environment
05
Analysis for design 3: embodied energy
An introduction to embodied energy
significant. Since reductions in the operational
of materials.The body of research reveals that natural materials such as stone have
energy component are currently being
low embodied energy. Reinforced concrete,
turing of construction material, its t ransport,
researched,the relationship betw een
bricks, concrete blocks,timber elements and
its installation and ultimate renovation or
embodied energy and operational energy is
other wood products such as laminated
demolition is almost always in the form of
not discussed here. Instead,this text focuses
timber and plywood have higher EE values.
non-renewablefossil fuel which produces
on how typical forms of construction might
Timber,excludingtransportatio n,has a very
carbon dioxide (C0 2) emissions as a result
best be combined to creat e buildings of low
low embodied energy, but much of the tim-
of these processes.Atmospheric emission
embodied energy, regardless of the individual
ber used in highly industrialised countries is
levels are widely regarded as one of the
levels of embodied energy in the materials
imported, which forms a relatively high pro-
most significant considerations associated
used.
portion of the total embodied energy level
The energy consumed in the manufac-
ofthis material.The embodied energy of
with t he production of building material and, particularly, the emission of C02 as the chief
Embodied energy values
steel is higher still, with aluminium having by
The figures for embodied energy used in
far the most embodied energyof the com-
this chapter are those quoted byThe Institu-
mon buildingmaterials.These findings have
material can be considered to be the sum
tion of Structural Engineers of the United
led to an assumption t hat natural materials
of the energyused in the manufacture of
Kingdom in their publicat ion Building for a
are more sustainable.
it s components, transportation, assembly
Sustainable Future: Construction without
contributor towards climate change. The energyembodied in a building
Comparisons of embodied energy in typical forms of building construction
on sit e,together with its ultimate demoli-
Depletion, which lists the total embodied
tion and associated recycling. This embodied
energy for seventy-one materials including
energy must be seen in relation to the
transportation but excluding demolition or
overall amount of energy expended by a
recycling.These figures are consistent with an
building during its lifetime.The total energy
earlier UK Steel Construction Institute's pub-
embodied energy, two w orked examples
consumption of a building can be considered
lication,"A Comparative Environmental Life
have been taken for comparison.The first
to be the sum of its embodied energy and
CycleAssessment of Modern Office Build-
example is a set of options for the structural
its operational energy consumed in using the
ings" by K J Eaton andA Amato. Precision in
frame of an office building. Similar spans and
building during its lifetime. Embodied energy
measuring embodied energy is difficultwhen
loadings are usedfor a wide range of build-
In order to compare levels of
currently accounts for only around 10% of
the amount of energyused in the produc-
ings in the UK,from offices to educational
the lifetime energy expenditure of a build-
tion,transportation to sit e and installation of
buildings and hospitals.The structural frames
ing, based on a 50-year period. However,
the material varies between locations.
investigated use either steel or reinforced concrete.Timber was not considered as it
levels of the operational energycomponent are set to reduce significantly.This will be done by improvingthermal insulat ion and by a mixture of passive and active contro ls
Levels of embodied energy in building materials Current research has focused on levels
is not economical for large spans with high loadings.The second example comprises a set of options for wall cladding in different
that control ventilation heat loss and solar
of embodied energy in individual materials
materials.The tw o sets of examples could be
heat gain.This would makethe embodied
used in buildings rather than in specific types
used as part of the same building. Either a
energy component in a building even more
of construction,which use a combination
steel or concrete frame could be used with
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372
mm wide x 16000 mm long bay with inter-
The results are as follows:
mediate columns was calculated for each
I a) In-situ concrete fiat slab (virgin steel rein-
to find out how materials for both structure
option. Four options were examined: in-situ
forcement) 1.73 Gj/m 2
and external wall might best be used both
concrete fiat slab with concrete columns;
I b) In-situ concrete fiat slab (recycled steel
separately and together to achieve low levels
prestressed precast concrete hollowcore
reinforcement) 1.41 Gj/m 2
of embodied energy in their construction.
(wide plank) deck on a steel frame; light
2a) Precast concrete hollowcore floor / steel
Examples of roofs were not used since they
gauge steel floor cassette on a steel frame;
beams (virgin steel) 1.27 Gj/m 2
would have broadened the scope of investi-
composite concrete steel deck on a steel
2b) Precast concrete hollowcore floor / steel
gation too widely into comparisons of con-
frame. The structural options are based on
beams (multi-cycle steel) 1.05 Gj/m 2
struction methods for pitched and fiat roofs
alternative designs for a typical office build-
3a) Light gauge steel floor cassette / steel
in various configurations.
ing. For each option the weight of structural
beams (virgin steel) 1.46 Gj/m 2
any of the cladding options. The examples were intended to be used
The effect of thermal insulation on
components was multiplied by the embod-
3b) Light gauge steel floor cassette / steel
levels of embodied energy in the wall clad-
ied energy (Gj/m 2). Embodied energy levels
beams (multi-cycle steel) I .20 Gj/m 2
ding options was investigated as a separate
for each material were then added together
4a) Composite concrete steel deck / steel
exercise. Since most forms of thermal insula-
to find the overall value for the complete
beams (virgin steel) 2.28 Gj/m 2
tion can be used with most forms of build-
structural assembly Fire protection was
4b) Composite concrete steel deck / steel
ing construction, a comparison was made
added to the steel options to make them
beams (multi-cycle steel) 1.78 Gj/m 2
between the use of a material with very
as closely comparable as possible. For each
high levels of embodied energy (expanded
option, the total embodied energy was
polystyrene) and one with very low levels of
derived from the summation of the calculat-
the construction technique with the high-
It is clear from this information that
embodied energy (mineral fibre insulation).
ed embodied energy for each component. In
est embodied energy is the composite
Taking the 3x3 metre bay with a Ix I metre
all options an alternative has been calculated
concrete steel deck.The lowest figure was
window used in the cladding options, it was
using multi-cycle steel (steel that will be
for the prestressed precast concrete hol-
found that expanded polystyrene accounted
recycled at the end of the building's life) and
lowcore floor supported off a steel frame,
on average for 15% of the overall embodied
recycled steel reinforcement bars (recycled
closely followed by the light gauge steel floor
energy of the wall panel. Mineral fibre insula-
from an Electric Arc Furnace as is common
cassette supported off a steel frame.The
tion accounted for on average lessthan 1%
practice) from figures published in The Steel
embodied energy for the composite con-
of the overall embodied energy. Since the
Construction Institute's itA Comparative
crete steel deck solution is 80% greater than
type of insulation used with a particular form
Environmental Life Cycle Assessment of
the prestressed precast hollowcore solution
of construction has such a large effect on
Modern Office Buildings". Crushed concrete
and 56% greater than the light gauge steel
the level of embodied energy, it was decided
can replace up to 20% of aggregates in
cassette solution.The four options were re-
to omit thermal insulation from the following
structural concrete, but the embodied ener-
examined using multi-cycle structural steel
worked examples.
gy would not change substantially as aggre-
and recycled reinforcement bars.The results
gates have a low embodied energy,therefore
remained similar with the exception that the
Example I: options for an officebuilding frame
this option was not considered. The columns
embodied energy for the light gauge steel
in all options have been omitted, as their
cassette solution was only very marginally
contribution is deemed insubstantial.
greater than the precast concrete
The level of embodied energy in a 6000
hollow-
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373
Environment
05
Analysis for design 3: embodied energy
core solut ion. In conclusion. the options with the great est degree of material efficiency and
7) Steel framed curtain walling 1.26 Gj/m2 8) Bolt fixed glazing 0.80 Gj/m2
problems to overcome concerning thermal breaks in steel.
prefabrication resulted in solut ions with the leastembodied energy. The present popular-
The wall configuration with the lowest
ity of preassembled modular construction
embodied energy is the timber framed wall.
appears to be in tune wit h sustainable con-
The highest are the aluminium framed cur-
struction.
tain walling and the facing brick cavity wall. W hen steel is used for the framing solut ion,
Example 2:options for wall cladding The level of embodied energy (EE) in a 3000 x 3000 mm (10ft x lOft) bay of a
What are the best mixes between high and low embodied energy materials in typical forms of construction? In the examples, the combination of
the embodied energy of the curtain waIl-
materials consuming the least EE tends to be
ing drops to approximately halfthe level of
the combinations using the materials most
aluminium.
efficiently. A building constructed from a high
Amongthe options for opaque walls
embodied energy mater ial, such as a steel
facade was calculated for each option. Since
with a I metre square window, levels of
framed building clad in glazed panels, uses
thermal insulation has been omitted from
embodied energy are relatively similar
far less material than an equivalent design
the calculations, the U-value of each con-
between timber and reinforced concrete but
in reinforced concrete and has a lower
struction is not considered here. For each
the brick cavity wall has almost 5 times the
level of embodied energy. W hat is surprising
cladding panel option, it was assumed that
embodied energy of the timber framed wall.
is the comparison between different types
each panel would be supported by a floor
Among the glazed curt ain wall options, levels
of glazed walling and cavity brick construc-
slab/perimeter beam both t op and bottom.
of embodied energy are higher for steel than
tion.An uninsulated cavity wall with regularly
Components within each panel were sized
timber but bolt fixed glazing provides the
spaced windows and a shelf support angle
accordingly. Like the structural options, levels
lowest solution.W it h the obvious exception
has three times as much embodied energy
of embodied energy were calculated based
of aluminium and brick cavity, the levels of
as double glazed bolt fixed glazing, but both
on the weight of each material used in the
embodied energy are relatively similar for
forms of construction have a similar U-value.
assembly multiplied by the EE value for each.
a given configurat ion of opaque and glazed areas.
The results are as follows:
The EE level of facing brick is nine times
The exercise suggests that low levels of embodied energy can be achieved using mixed methods of lightweight and heavy-
I) Timber framed wall+double glazed window 0.48 Gj/m2
that of concrete block andtwice that of
weight construction in a single building. From
common brick. Bolt fixed glazing minimises
the above examples, the best combination
2) Timber framed curtain walling 0.82 Gj/m2
the use of materials, using glass as panels
might be a timber clad precast concrete
3) Reinforced concrete panel+dg window 0.70 Gj/m2
which are unrestr ained along their edges.
solution or a bolt fixed glazed facade with a
The use of aluminium framing results in
light gauge steel cassette solutio n.The worst
4) Facing brick cavity wall+double glazed window 2.33 Gj/m2
there being three times as much embodied
combination would be a brick clad com-
energy in the frame as in the glass.The use
posite concrete steel deck solution but this
5) Facing brick cavity wall wit h steel shelf angle 2.54 Gj/m 2
of steel framing is much better, using 60%
building combination has been extensively
more embodied energy compared to the
constructed in recent years.
6) Aluminium framed curtain walling 2.48 Gj/m 2
bolt fixed glazed units. Nevertheless, from
MCH
374
a performance point of view,there are
This puts greater emphasis on the need for an efficient use of material where
5% of the
high embodied energy materials are used.
metal requires only about
Aluminium seems to be a very extravagant
energy needed to make the same amount
solution for low embodied energy and,
material in terms of energy.This is mainly
of metal from bauxite.
hence, provide a sustainable construction.
because when used in building components, aluminium is required to have high rigidity as
The manufacture of building materials has a direct impact on our environment.
a timber facade may provide an optimised
Both solutions rely on a high degree of specialist prefabrication and preassemblyThis
well as high strength.The material is used for
Removing raw materials from their natural
is good news and bad news for traditional
the precision of its extrusions and castings
environment can cause long-term damage
construction. The focus should be on prefab-
rather than for any real qualities of lightness.
to the environment.The extraction of ores
rication and efficient use of carefully selected
This is not the case where aluminium is used
to make steel and aluminium leaves holes in
material. It appears that prefabrication and
in other industries. In aircraft design, alu-
the ground. Mining areas can be re-instated.
preassembly can provide the means to a
minium is used for its strength and lightness.
Trees cut down as a result of timber pro-
future in construction that is flexible, adapt-
Rigidity is much less important, as part of
duction can and should be replanted and
able and sustainable.
the aircraft can deflect without significantly
replaced.The cost of this work will have to
impairing performance.
be added into future calculations of embodied energy Care should be taken to establish
Recycling and sustainability
Embodied energy values used GJ/tonne
the source of timber. An area of tropical forest corresponding to the size of the
I) Aluminium alloy
200 Gj/tonne
energy level in the construction of a building,
United Kingdom is being destroyed or seri-
2) Synthetic rubber
150 Gj/tonne
the levels of EE in different materials might
ously degraded every year. Therefore, timber
3) Structural steel
suggestthat prestressed concrete and tim-
should be selected from an audited and
4) Steel used in windows
ber are preferable to steel and aluminium.
sustainable forest or from plantations already
5) Float glass
15 Gj/tonne
However, these criteria must be seen within
established on degraded land. Planning the
6) Softwood
I 3 GJltonne
the overall context of recycling non-renewa-
life of the building as appropriate in environ-
7) Plasterboard
2.7 Gj/tonne
ble resources and a sustainable approach to
mental terms will become a higher prior-
8) Facing bricks
I 1.7 GJltonne
In attempting to reduce the embodied
26.8 Gj/tonne 31 Gj/tonne
ity This might lead to the preassembly of
9) Mortar
shop-constructed components which can be
10) In-situ concrete structure above ground
not used in many parts of the world, where
readily adapted to suit changing needs using
1.09 GJltonne
the ready supply of timber, for example, can
a kit of parts or can be dismantled and reas-
I I) Steel reinforcement
provide a more appropriate material. Steel
sembled as the need arises. This might lead
12) Plywood
and aluminium, with much higher embodied
to a scenario where modern high embodied
I 3) Concrete block
1.3I Gj/tonne
energies, are more easily recycled. Once
energy buildings will be demolished and
14) Wall insulation
35 Gj/tonne
manufactured, these metals are in a fairly
recycled rather than maintained, but mason-
15) Plastic
150Gj/tonne
'closed' cycle of re-use. Aluminium is one
ry buildings of heritage may be allowed to
of the easiest materials to recycle and at
remain without fear of being recycled.
the use of renewable resources. Bricks and blocks can be re-used, but are
reasonable cost. Energy savings are made
In conclusion, a well conceived light steel
by recycling the material.The conversion
structure with bolt fixed glazed facades or a
of scrap aluminium back to high-grade
prestressed precast concrete structure with
0.84 Gj/tonne
26.8 Gj/tonne 17 Gj/tonne
MCH
375
....._--
Environment 05 Passive design I: natural ventilation
The British School in the Netheriands.The Hague. Holland. Architect: Dirk Jan Postel. Kraaijvanger Urbis. Kew House. Melboume.Australia. Architect: Sean Godsell
The return t o natural ventilation in buildings,
temperature and steady rate of vent ilat ion.
due to internal heat input from casual and
and away from dependency on mechanical
In addition,air conditioning systems would
solar gainsto the vent ilating outdoor air.The
ventilation (including air conditioning), has
control humidity aswell as temperature.
temperature, and consequently density dif-
gathered momentum in recent years. This
This high degree of environmental control
ference between indoor and low level sup-
has come about from the desire to reduce
led to very high energy consumption from
plied out door air results in an upward flow
both the energy consumption in build-
running the equipment. In urban areas,the
(buoyancy).Air moves from low level t o high
ings andthe wider issue of carbon dioxide
use of operable windows to provide natural
level in a building with a highertemperature
(C02) emissions from the primary energy
venti lation is often considered inappropriate
than that outside whilst the reverse will
generation through to building use.The link
due to high levels of noise and atmospheric
occur if the air in the building is cooler than
between global warming and the build-up of
pollution.This has led to the development of
that out side. Natural ventilation has two main ben-
greenhouse gases hasyet to be conclusively
'layered' systems in which functions of sound
proven, but the circumstantial evidence
insulation,weatherproofing and air infiltration
efits; reducing the amount of mechanical
seems convincing. Nearly half of C02 emis-
are separated.
ventilation needed during normal daytime
sions generated in the UK alone arise from
Natural ventilation in buildings is gener-
use,and providing free nighttime cooling
ated either by wind or by a 'stack effect'. In
of the building structure. Heat generated
reduction of energy consumed in buildings
most buildings a combination of both occurs.
during the day will be absorbed by the
has a hugebenefit forfuture generations.The
As air flows across a building, a difference in
structure if exposed,which leads to a slower
decline in the supremacy of air conditioning
air pressure will occur as a result of varying
rise in resultant temperatures within the
can also be linked to 'sick building syndrome'
wind pressure.This difference in pressure
building. In order for nighttime coolingto
due mainly t o systems dependant on the re-
causesthe air in the area of higher pressure
benefit daytime internal comfort,the build-
circulation of used air in buildings.
t o flow towards the area of lower pres-
ing structure requires a medium t o high
sure. Provided openings are appropriately
thermal mass which should be exposed to
located in these pressure regions, the move-
the occupied zone.A structure with high
energy consumed within buildings.The
This has resulted in the increased use of openingpanels and window systems. Previously, building types other than housing
ment of air creates a natural venti lat ion flow
thermal mass, such as concrete soffits, cooled
were often designed as hermetically sealed
through the building. 'Stack effect' ventilation
at night will absorb much greater amounts
boxes which aimedto provide a constant
is caused by a difference in density of air
of heat generated within the building dur-
MC H
376
Southern Zone Offices - Cross Section
INTERNALBLINDS TO CONTROLGlARE EXlRACT DRAWN BYSTACK EffECT THROUGH ATRIUM W INTERSUN CAN ENTER AND WARM INTERNAl SPACE
~====================~===:/ ,
EFFECTIVE SHADINGfll:OM
RADIANT
COOUNG fROM
cONvlcnVE G....INS
slAa
OVERHANG
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FROM PEO PlEAN D EOUIPMENT
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WtiITESHADES ACT ASlIGHTSHElVES INCREASING
RADIANT
COOUNG fROM SlA8
POWER DATA
DAYliGHTlEVElS
oonn aoXES l ~flOOR
ElECHllCPE RIMElER HEATER
OUTlET FROM StABINTO flOOR vOID
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WEATHER STATION CONSTANTlY MONITORS CLIMATE & Al lOWS CONTROL Of VENTILATIO N & TEMPER ATURE
PREVAILINGWINDS ASSIST NATURAL VENTILATION ~
.
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SHADING SYSTEM PROVIDES PROTECTION f ROM SUNLIGHT ENSURING GOOD DAYLIGHT PENETRATION
ing the daythan will a lightweight structure
SOUTH SIDE NATURAllY I ENTILATED
\.
~~~8=2iii¥25!i==~~~
with low thermal capacity such as steel.A considerable amount of research into the effect on thermal mass performance due to different slab construction methods was
lonica Building, Cambridge, England.
recently published.Where the contribution of thermal mass is to play a part in the internal environmental strategy, the preference for exposed concret e soffits is particularly important given that external wallstend to have a high percentage of fully glazed walls. In addit ion,during winter months, natural ventilat ion can be used t o redistribute heat stored in the building structure to help
_ - : : ; ' _1 1
/ /~ // ~
keep the building warm at night.There are a number of proven methods whereby thermal mass is used to exchange heat with vent ilating air st reams.These are generally mechanically driven due to the airflow resistance normallyencountered.This approach can be via hollow core pre-cast slabs as used on the lonica building in Cambridge, England, which are linked t o form concrete looped passages to optimise heattransferbefore su pplyingthe air t o the occupied zone. lonica Building, Cambridge, England.
MCH
377
Environment 0 Passive design 2: daylighting and solar shading
Details I. Fixed ferro-cement louvres 2.Glazed rooflights 3. Support trusses for louvres
A space wit hin a building lit by natural day-
W ith increased daylighting,there is often
light produces about one tenth the amount
an increased amount of solar gain particu-
of heat created by an equivalent incan-
larly on those facades facing the sun.This has
descent lighting installation and about one
brought the issue of solarshading into sharp-
half of that of a discharge lamp installation.
er focus. Even facades with low percentages
This, along with the desireto offer greater
of glazing ( I0 - 40%) are increasingly using
naturally lit space, has led to the increased
solar control devices instead of relying heav-
useof daylight as part of the drive towards
ily on mechanical cooling. A popular method
reducing the in-use energy costs associated
of solar shading has been the use of exter-
with mechanical cooling. In addition,there
nally mounted canopies and screens.A vari-
has been a move away from reflective glass
ety of horizontal continuous canopies, verti-
and body-tinted glass to increased transpar-
cal blinds, fixed louvres and movable screens
ency and admission of daylight. Increased
is used. External shading has the advantage
daylighting can increase the problem of glare.
of both controlling the passage of sunlight
Viewing two highly contrasting levels of light
and reflecting heat away from the sun out-
at the same time causes glare.The huge
side the building envelope.The positioning
increase in the use of computers in buildings
of solar shading inside the building envelope
and the need to see monitor s clearly has
results in some of the heat being reflected
CarterlTucker House,Victoria.Architect:Sean Godsell madethe problem allthe more important.
backout of the building, but more than 50%
Conventional solar shading, which projects
is radiated into the building, providing little
horizontally from the wall plane reduces inci-
advantage in controlling solargain.Although
dent solar radiation and therefore reduces
external shading provides better reduction
heat build-up in glazing, but it only reduces
of solar gain than an internal fixed type, the
glare to the extent that it obscures part
components will require cleaning and main-
of the bright sky. It cannot obscure the sky
tenance.This has led to the increased use of
at the horizon, nor can it deal with bright
access decks or walkways, which also provide
reflections from objects at eye level.These
a degree of horizontal shading. However, this
two sources of glare are particularly char-
method imposes a high maintenance budget
acteristic of very open environments. Glass
and commitment on the building occupiers.
treatments such as fritting,silk-screening
An alternative solution isto set the shading
and sandblasting merely diffuse brightness
behind an outer glazed wall such as a rain-
and can even make the problem worse.
screen, which draws radiated heat directly
The solution requires the introduction of a
away from shading components prior to its
mechanism to control overall light transmis-
reaching the inner glazing.This heat gain can
sion and therefore light intensity, thus ena-
be drawn away by natural ventilat ion, when
bling a reduction in perceived contrast.
external air temperatures permit, or by mechanical means.
MCH
378
I The Menil Collection Museum, Houston, USA.Architect: Piano and Fitzgerald.
Solar shading and daylight controls Shading devices used to control solar
tops reflect heat but allow light to reflect off the surface and into the spaces beneath.A
gain andthe admission of daylight fall into
more modest approach to applied shading is
tw o generic types: 'integrated' shading and
the 'light shelf principle, a horizontal reflec-
'applied' shading.
tive shading device that projects through the
'Integrated' shading uses components
facade both to shade sunlight and reflect
set within the depth of a cladding panel.
light off its upper surface and across the
One of the most technically sophisticated
adjacent ceiling.This helps to even out day-
examples is the Institut du Monde Arabe in
light levels wit hin deep spaces with a shallow
Paris, designed by a team led by the architect
floor-to-floor depth that require good natu-
Jean Nouvel.The principle is based on pho-
rallight, such as in office buildings.
tographic iris diaphragm aperture control,
This 'layered ' approach is used in the
an instrument that precisely controls the
Bibliotheque Nationale in Paris,which fea-
intensity of light, and this was used in glazed
tures all-glass facades.The project team, led
cladding panels on the south facade. A set of
by Dominique Perrault, tackled the problem
computers responds to direct solar radiation
by introducing a fine metal mesh on an inde-
by operating shutters in each panel.These
pendent frame offset from the external face
shutters control the amount of sunlight
of the glassViews are maintained through
enteringthrough the south facade of the
the light veil of stainless steel which creates a
building. This allows both the admission of
gentle hazyquality internally.The mesh mate-
daylight and solargain to be closely control-
rial provides a textured and sparkling surface
led with a single mechanism wit hin the clad-
externally, which complements the smooth,
ding panel itself More typical examples use
reflective appearance of the glass skin.
motori sed blinds set wit hin a sealed glazed
Other recent examples include the Berlin
cladding panel.
Velodrome also designed by Dominique Per-
'Applied' shading sets components as a
rault andthe Euralille Commercial Centre
separat e layer to the (usually glazed) weath-
at Lille by Jean Nouvel. In order to facilitate
erproof layer. A typical example isthe Menil
glass cleaning, mesh screens can be placed
Museum in Houston,Texas. designed by the
at a distance from, or tilted away from the
Renzo Piano Building Workshop. Daylight
plane of glazing. Alternatively,the screens
baffles, which also provide solarshading, are
can be designed to unclip for easy removal,
made in a lightweight concrete construction,
or can be motor-controlled in an overhead
mounted beneath the glazed roof. Besides
or roller-shutter format.
controllingthe amount of daylight and diffusing it,the white-finished louvre blades are shaped to reduce internaltemperature variations from solar radiation.Their horizontal
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379
nvironrnent 0
----
Passive design 3: solar power
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GovernmentTraining Centre, Herne-Sodingen,Germany. Architect:Jourda Perraudin.
Photovoltaic panels Photovoltaic (PV) cells are used to generate electricity from sunlight.The power generated is then used inside the building to contribut e to the electrical demands of the building and, in some cases, the power generated can be sold backto the electricity supplier. Electricity isgenerated in arrays of cells set in panels on roofs and facades. The orientation of panels is important.Those inclined closeto the horizontal produce more electricity annually than those inclined vert ically. Panels are set as close as possible to the angle at which the most amount of electricity isgenerated over a one year period,t aking into account the varying path of the sun duringthat period and the effects of diffused solar radiation. Panels comprise a glass substrate coated with tin oxide, forming a transparent electrode, which is covered with layers of silicon together wit h a coat of aluminium film, which forms the other electrode. Particles of ultraviolet light called photons interact wit h electrons in the semiconductor to convert sunlight into direct current electricity.PV cells are of three types: multi-crystalline, which produces the most
MCH
380
University of Northumbria.UK.
amount of power per unit area, mono-crys-
Daily operating periods range from fifteen
talline, which produces less but is cheaper;
hours in May to eight hours in January. It is
andthe thin film type which is currently
estimated that the installation paid backthe
made only in one fixed panel size but which
energyused in the manufacture of the cells
is yet cheaper' and can be fixed into a glazed
within three years, and is still expected to
walling system.
produce electricity for a further 20 years.
The photovoltaic process has the advan-
However; the cost of generating electricity
tage of requiring no moving parts. It requires
is about four times the current commercial
no fuel and needs relatively little mainte-
rate.The PV cells are integrated into the
nance.The amount of energyrequired to
facade with a rainscreen cladding system.The
manufacture the PV cells and deliver them
cladding is inclined at 26° to the vertical,also
to site is estimated by manufacturers to be
providing passive solar shading.Ventilating
equivalentto the amount of energydeliv-
the void behind the panel disperses heat, a
ered in the first three years of use; the PV
by-product of the photovoltaic process.
installation will continueto produce power for the next twenty years or more.
Here,the array of PV cells is divided into a series of units 3.0 x 1.36 metres. Each panel is demountable for ease of mainte-
A sampled photovoltaic panel installation An early large-scale PV installation, from
nance or replacement.The cells are bonded to an extruded aluminium frame wit h
Details I,Window 2, Photovoltaic panel
3. Supporting frame 4. Structural wall 5. Floor construction
structural silicone. Excess electricity can be
which a relatively long performance has
exported to the electricity supply company.
been recorded, is at the University of North-
The electricity generated meets50% of the
umbria in England.The output of electrical
building's electricity needs in summer and
power fluctuates with weather conditions
10% in winter; which averages out at 30%
and it is necessary to supplement the supply
over a one-yearperiod.
with electricity from conventional sources.
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381
Environment 05 Passive design 4: solar heating
- - --.
Solarchis Solar Houses, Japan.Architecture Studio and Maeta Concrete,
Solarheating systems consist of collector
ping this radiation to be absorbed by the
tion with a photovoltaic array on the roof
panels that absorb heat from solarenergy
receiver surface.This surface isa copper
and a wall construction with high thermal
to warm circulating water. Heat absorbed
base platethat transmits the heat to a con-
mass internally and thermal insulation fixed
bythe water is transferredto a storagetank
tinuous pipefixed to its rear face. The pipes
externally.The Iyama House has a solar
by pumping or when positioned above the
are enclosed in thermal insulation to reduce
water heater installed in a transparent roof
collectorthe two components form a ther-
heat loss to the air.The most populartypes
that produces domestic hot water at 50°C
mal circulating system. In the latter case.the thermo-siphon effectof water movement is
of panels currently in use are: a) flat plate collectors, b) vacuum flat plate collectors
in a 300 litre storage tank. Food iscooked mainly by a solar steam cooker with the sup-
created by the density difference between
and c) evacuated tube, (the latter being the
port of an electromagnetic induction heater
hot and cold water.The heated water is nor-
most efficient over a typical annual tempera-
which uses high-temperature solardomestic
mally used to exchange heat with a build-
ture/solar radiation yearly profile. whilst the
hot waterfrom a 20 litre storagetank.The
ing's system water, which isthen distributed
addition of a vacuum void to flat plate col-
House of the Sun (above) has a system of
around the building as required for either
lectors significantly improvestheir efficiency).
evacuated tubularsolarcollectors heating
heating water or as domestic hot water.The amount of heat generated is significant and
Solarabsorbers have been used for many years to provide warm water of up 500C
water stored in a 300 litre tank.The cooking system is similar to that used in the Iyama
whilst it is currently suited to climates that
to
have abundantsunshine for much of the year,
of special solarabsorbing high-grade rubber
the performance efficiency has developedto
mats with integral water flow channels for
from solarenergy have been in develop-
the extent that Northern European states
circulating the pool water.They can also be
ment since the I 850s. An early example
can also benefit. Collectorpanels should ideally be ori-
used for domestic warm water supply.
was a boilerand power plant for water
entated to face south and in the UK, they
ing System in Japan, set up by the Solar
sisted of five long parabolic mirrors.each
should be angled at 450 from the horizontal.
Architecture Studio and Maeta Concrete
4.2 metres wide by 62 metres long. Steam
Panels traditionally consisted of sheets of
for swimming pools.They consist
A recent example isthe Solarchis Hous-
House. Devices for obtaining hot water directly
pumping built near Cairo in 1913. It con-
Industry Ltd. Demonstration houses built
was produced at slightly above atmospheric
clear high light transmission glass that allows
in the Yamagata Prefecture, Japan, use roof-
pressure and used to drive a 20hp water
maximum solar radiation penetration, trap-
mounted solarwater heaters in conjunc-
pump. Itwas abandoned during the First
MCH
382
Daggett SolarFarm, California, USA.
WorldWar. Modern solarfurnaces still use a similar system of mirrors. Recentdevelop-
WINTER
ments, prompted by the space programme in thermo-electricity and photo-electricity, Sunlight at the
are used both to run water-heating systems
winter sotstice
and to generate electricity. Only a few largescale solarfurnaces have been built.The 10.5 metre diameter mirror and heliostat at Montlouis in the French Pyrenees are used for research into materials at high tempera-
~
tures rather than as an economic source of
~~ ,.:.,~. .
Concrete panel
:'
'
(heat-conclucting facing)
heat.
Pressure-tight concrete board
A recent installation isthat at Daggett SolarFarm, California, USA where electricity
SUMMER
is generated from an array of parabolic mir-
I
rors, arranged in long rows,that heat liquid in
PV power generationand solar hoi water supply
pipesset intothem.
Sunlight at
summersolstice
Heat absorption
D-D-D-
il.=========!JJ I j-
-
Cold storagein the concrete structure Heat·insulatingmaterial
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383
Environment 05 Low energy material systems I : straw bales and hemp
.0
ModCell Panel Module ModCell is based on a 3 bale wide by 8 bale high standard module. A typical panel is approx 3.2m x 2.9 m x 5 10mm unit.
3-D view of modularised componentsthat can be created using the modCell system
Details l .Timber frame 2 Straw/hemp/paper bales 3.Steel rods 4.Openings for windows doors etc. 5. Lime based render (applied over bales) Key uValue data ModCell Straw 450 mm 0.1 3 ModCell Hemp 300 mm 0.26 ModCel1 Hemp 500 mm 0.16 ModCell Paper200 mm 0.1 6 Building Regs CavityWall 0.35 ModCell straw panel being constructed(left) and Modcellhemp (right)
ModCel1 is a modular system of building
and height according to the individual project.
ModCell Paper
utilising renewable materials such as straw
Wit hin t hese panels open areas for windows
Each has a particular set of performance criteria,designed for different applications:
bales, hemp and paper as its insulating
and doors can be left available according to
core. These off-site manufactured panels
the design. Currently these units have been
mean that buildings can be quickly and
used as loadbearing elements up to three
efficiently installed on site making it ideal
modules (approximately 9metres high)
for large scale commercial, school or office buildings
A major advantage of these panels is
ModCell Straw uses straw bales as its insulation core. Straw is an agricultural by-product ,and almost 3 million tons are
their thermal performance which is up to 3
disposed of annually in the UK alone.The
Each panel is made up of a sustainably
timeshigherthan the current building regula-
straw panels creates a mass market use for a
sourced timber frame into which t he insulat-
tions. As a result, buildings using ModCell can
valuable and renewable resource that would
ing material is insert ed.The straw bale and
have zero heat requirements, saving money
normally be chopped and ploughed back into
paper panels are then kept in place by steel
and C02 emissions. The main disadvantage
the ground. ModCell Straw has exceptional
rods with all the panelsfinished off with a
of these panels is with the thickness of the
insulation propertiesand can be used both
layer of lime render which as well as being
panels which typically are approx. 450mm
dry lined and rendered.
a natural product also has the essential
thick.
attribute of providing a breathable layer to the panels. The diagram above illustrates some of
The current range of ModCell panels
ModCell Hemp uses hemp mixed with lime in the panel,these panels are slight ly
uses three types of Cellulose Insulation
thinner in depth to provide similar thermal
Cores (C1C):
mass benefits to that of the straw panels.
the various modulesthat can be utilised in
ModCell Straw
ModCell Paper uses recycled paper
construction using panels of a certain width
ModCell Hemp
which provides a light er-weight construction
MCH
384
alternative to Straw and Hemp with again similar thermal advantages. ModCell panels are constructed off-site but in order to minimise energy in transport in existing projects 'flying factories' have been set up for manufacture. These have been located within 10 miles of the site in agreement with local farmers who have been able to provide a source of straw and a suitable
The Archimedia Project, Bristol, UK ModCell Straw
locat ion to assemble the modularpanels. By usinglocal straw, skills and labour, the project's value can also be kept within the local economy
Straw Straw bale construction is a building method that uses straw bales as structural
Strawbale dance studio, London. Strohaus.Architeet: Felix Jerusalem
elements, insulation, or both.As with the modCell system it is a material that excels in the areas of cost-effectiveness, energy efficiency and ease of availability. A typical bale of straw has a U-value of O.13W/m2K. The constr uction typically consists of stacking rows of bales on a foundation plate with a vapour barrier to protect t he straw from damp.These are then t ied together with pinstypically made wit h wood or with wire meshes.These walls can then rendered with a lime or eart h/clay based mix. Because the building method is so straightforward, people without previous building experience can
Strawbale classroom at AvonTyrrell. New Forest, UK
participate in the design and construction, thereby savingon labour costs. Typically bales created on farms with baling machines have been used, but recently higher-density 'precompressed' bales, or 'straw-blocks', can increase the loadst hat may be supported. The main concerns wit h straw bale construction like many of these natural building materials are to do with keeping t he bales dry. Splash back from rain bouncing up from the ground, rain causing high humidity or w ind driven rain are the main problems.These however can be easily mitigated with adequate foundatio n design, a suit able render and protect ion by large overhanging roofs.They are also constructed of breathable materials and need not be wat erproofed, t hough t hey must be weatherproofed.
The straw house. London,Architect: JeremyTill and SarahWigglesworth
MCH
385
Environment 05 Low energy material systems 2: rammed earth, cob and adobe bricks
- - -....
Left to right: Entrance building, Eden Project Cornwall,England,Detail of rammed earth wall,The Redding Residence, Kendle Design Collaborative,Scottsdale,Arizona, USA. Detail of example of rammed earth colouration through varioussoil types
Leeum - Sarnsung Museum of Art in Seoul, South Korea.Architect:Jean Nouvel
Compacted earth construction is a
After compressionthe wall frames can
Apartheid Museurn, Johannesburg,South Africa ied energyand generate very little waste.
technique used in the building of walls using
be immediately removed and require an
Coloured oxidesor other items such as
the raw materials of mud, chalk, lime and
extent of warm dry days after construction
bottles or pieces of timber can be used in
gravel where moist loose earth is compacted
to dry and harden.The structure can take
construction to add variety andtexture to
in layer between shuttering or formwork to
up to two years to completely cure,and
the finished wall.
construct a wall.
the more it cures the strongerthe structure becomes.W hen the process is complete it is
Gabions are boxes made of metal, plastic
seen a revival in recent years.The nature
much like constructing a hand made wall of
or reed mesh filled in-situ with rock or cob-
of the materials used rneans that it is non-
solid rock..
bles and used as a basic building unit.
It is an ancientbuilding method that has
combustible ,thermally insulating and very
Like other natural building materials
Gabions have a long history in civil engi-
strong and hardwearing. It also has the added
rammed earth walls needto be protected
neering, as retaining walls and in erosion con-
advantage of being a very low cost and sim-
from heavy rain.They are typically con-
trol but today they are becoming commonly
ple way to construct walls.
structed on top of conventional footings or
used in structural walls in buildings particu-
a reinforced concrete base, sometimes with
larly as a feature in projectswhere the cages
The exact composition of the soil and water in rammed earth walls is critical for it success.A small proportion of cement
extra ground insulation. One of the significant benefits of rammed
can be filled with any recyclable material such as glass bottles,or local materials.
or lime is sometimes addedto the mix as
earth constructions istheir excellentthermal
a stabiliser to correct any deficiencies in its
mass;(atypical rammed earth wall is about
in the low embodied energy and use of local
360 mm): it heats up slowly during the day
materials as well as providing a large thermal
makeup.
The main advantages of the system are
As well as this, good compaction opti-
and releases its heat during the evening. On
mass to control the internal environment
mises the strength and stiffness of the mate-
the other hand, rammed earth is not a good
of buildings. How they are weat herproofed
rial. There are three main methods in which
insulatorand is often insulated in colder cli-
is the rnain disadvantage with an additional
to do this:
mates.The thickness and density of the walls
layer required in addition to the gabion wall if
lends itselfnaturally to soundproofing and
a sealed environrnent is required within.
• Static (block presses)
the materials used in the walls make them
• Dynamic (rammed earth)
highly fire resistant Rarnmed earth structures
• Vibration (wacker plate)
do utilise locally available materials, which means that they also have very low embod-
MCH
386
Adobe House,Choisica,Peru
The Cobtun House,Worcestershire, UK.
Mud-brick! Adobe is a natural build-
massive wallstypical in adobe construction.
Cob is a building material consisting of clay.
ing material made from sand, clay, and water,
The cost of t he material and low embodied
sand, straw,water,and earth, similar to adobe.
with some kind of fibrous or organic mate-
energyassociated with being found on site
The main advantages of cob as a material is
rial (sticks, straw, dung), which is shaped into
mean it has a very low environmental impact
that it can be used to create artistic, sculp-
bricks using frames and dried in the sun. It
Adobe structures are extremely durable
tural forms using local materials. It is also
is simi lar to cob and mudbrick,although it
and account for some of the oldest extant
fireproof, resistant t o seismic activity,and
requires a higher clay content than that for
buildings on the planet. However in order
inexpensive.
rammed earth. Excessive amounts of clay
t o protect them from damage from rain etc
however may lead to shrinkage cracking in
coatings renderings or cladding are usually
construction.
In the UK cob is most strongly associated with the counties of Devon and Cornwall
applied to t he structure and projecting roofs
and in Glamorgan and Gower peninsula in
Bricks are typically made in an open
or other structures considered in the design
the UK. Traditionally it was made by mixing
frame. The mixture is moulded by the frame,
to shed heavy water away from the walls. It is
the clay-based subsoil with straw and wat er
and then the frame is removed quickly.After
also import ant that the bricks are protected
using oxen to trample it.The earthen mixture
drying a few hours, the bricks are turned
form the damp by building onto a plinth at
was then ladled onto a stone foundation in
on edge to finish drying. Slow drying out in
least ISOmm from the ground.
courses and trodden onto the wall by work-
direct sunlight reduces cracking.Tradition-
Other disadvantages are with the
ers in a process known as cobbing.After dry-
ally bricks are made on sit e in arid countries
required thickness of the walls and the labour
ing,the walls would be trimmed andt he next
where there is little risk of rain for the drying
and time involved in the manufacture of the
course built, with lintels for lat er openings
period (between 2 and 8 weeks).Today many
bricks. Particularly in the UK the weather
such as doors and windows being placed as
are made in factories constructed for the
poses a big threat to the construction and
the wall to ok shape.
project on site or in the locale.
maintenance of an adobe/mud brick building.
The walls of a cob house are about
Basic construction of adobe or mud
Due to these factors very few examples of
600mm t hick, and openings therefore
brick buildings follows the principles of block
this form of construction exist in the UK at
become correspondingly deep set.The thick
masonry. The blocks are typically laid in weak
present.
walls provide excellent thermal mass and
cement lime. sand or earth mort ar or can be
the material has a long life span even in rainy
dry stacked.
climates if a tall foundation and large roof
The main advantage of an adobe wall
overhang are present.
is in its thermal properties inherent in the
MC H
387
nvironment 05 Low energy material systems 3: green wood and bamboo
Above and right:: The National Maritime Museum, Falmouth,UK,Architect: Long & Kentish.
GreenWood A s opposed to regular timber used in construction, green w oo d is ti mber in w hich the cavities contain water. The primary reason for use of green
Visitor Centre. Savill Gardens,W indsor,UK,
air dr ying (2 to 3 years) and th en t he kiln
t he constr uctio n of green w ood buildings,
dr y.
as w ell as t he connections and det ailing Green oak, like othe r forms of tim -
ber, is a carbon neut ral prod uct that has
t o com pensate fo r any movement in t he
absorbed C02 throughout its natural life-
dr ying process.
oak, hist ori cally, was to enable it t o be
span and do es not emit carbon dioxide
w orked with hand too ls, D r y oak is very
w hen it is felled or used for construction
hard and extremely difficult to saw, plane
purposes,
or chisel.Today th e main reason is envi-
of buildings need careful consideration
It is also replenishable. Q uick grow ing
Bamboo When t reated , bamboo forms a very hard w ood w hich is bot h lightweight and
ronmental in te rms of the cost and ti me
hardw ood species like spruce and oak
except ionally durable unlike many othe r
involved in drying.The rat e of drying of
are ideal w oods wit h w hich to build, pro-
woods, whic h can be heavy and soft.
oak is approximat ely 25m m per year,so
viding load-bearing st rength and durability.
Tradition ally, it is used in tropical cli-
th at a 300 x 300mm t imber w o uld t ake
Green oak frames are considered
mates in element s of hou se construction,
I 2 years to dry for construction. The cost of freshly felled (green) oak is co nsiderably cheaper th an the dried
attracti ve because the y showcase the
scaffo lding, and as a substit ut e for st eel
skills of craftsmen, particul arly the joints
reinforcing rod s in concrete construction,
w hich are fixed using oak pegs.This is
The main advant age environmentally
prod uct after processing. Freshly felled
st ill done because met al fixings w ou ld
is in bamboo's rapid growth w hich is very
at the roadside a piece of t imber costs
corrode in th e mo ist, acidic environment
fast, up t o 25met res over 6 mon th s, w it h
approximat ely one tenth the cost of the
of t he unseason ed w ood.T his met hod
th ree to five years to mature. Th is unique
mat erial after pro cessing at th e sawmill ,
requires specific skills and t echniques for
characteristic makes it one of the mo st
M CH
38 8
o Centro Cultural Max Feffer,Brazil. Archit ect: Leiko Motomura Connection detail below
o Centro Cultural Max Feffer,The largest bamboo structure in Brazil. Architect: Leiko Mot omura rapidly renewa ble constru ction mate rials
The str ucture of bamboo consists
available as we ll as a fairly inexpensive
of hollow cylindrical stems called culms.
mat erial. In th e Un ited St ates and in
T he culms are segmented int o nod es and
France, it is possible to have houses made
int ernodes.T his structure gives the mate-
entire ly of bamboo. which are earthquake
rial ver y good compressive and tensile
and cyclone-resistant and internationally
strength in construction as w ell as th e
certified.
huge benefit in w eight in comparison to
However; bamboo wood can becom e
METI School in Rudrapur,Bangladesh. Analogue construction using local resources.
other w ood materials
easily infested with wood-boring insects unlesstreat ed with wood preservatives or kept very dr y. The main disadvant age in t erm s of use as a global building material is in th e current limit ed regions in which it is grown. Bamboo can be grown in a variety of climates including the U K
INTERNOD E
but currentl y it is more economical to impo rt t he material in from exist ing bamboo plantations whi ch incurs large cost
DIAPHRAM
t o the environ menta l accreditation of th e material through tra nsportation.
MC H
389
Environment 0 Low energy material systems 4: green walls
Modular system wit h soil substrate: Eco Store, London.
Green wall design Green walls are living, self regenerating cladding systems that allow building
Tensioned wire green wall, Heathrow Airport, UK.
advancements have enabled living walls to
ate a cooling effect as a result of evapora-
become fully integrated facade systems in
tion
new developments.
facades to be covered completely with vegetation.The concept has been in existence for centuries. In the Mediterranean, plants are often trained over facades to
Living w alls are an excellent w ay of introducing biodi versity into urban envi-
Advantages and disadvantages Living w alls offer a number of environmental benefits:
ronments although the presence of mice or insects may cause problems. Without proper planning living w alls can cause building damage. Planting
act as a natural means of climate control.
Planted facades can help regulate
Fruit plants in particular thrive in this situ-
internal temperatures. In the summer the
systems can impose additional loads on
ation since the heat stored in the backing
vegetation shades the w all from the sun
external w alls.T hey can also affect the
w all is particularly conduci ve to plant
and can reduce the daily temperature
structural balance of the building. Roots
growth.
fluctuations by up to 50%. In the winter
and tendrils can break through water-
an evergreen facade will provide insula-
proof seals or force their w ay behind
'living walls' has expanded into the public
tion not just by trapping air between the
cover strips and w indow abutments and
realm to the extent that veget at ion can
planted zone and the wall, but also by
without regular maintenance, leaves and
now be seen adorning the facades of
reducing the wind chill on the facade.
other dead matter can block gutters and
In recent year s,however; the use of
museums, shops, community centres and offices.
Living w alls can also benefit the sur-
rainwater pipes.
rounding environment by altering the
Living w alls can help to link buildings
local microclimate.vegetation helps w it h
System overview
with their natural environments. In cities
noise absorption and can lead to an
large planted facades have a dramatic
improvement in the atmosphere through
egories: Individual point plantings require
Living w alls fall into two main cat-
visual effect and can act as an oasis of
the dust trapping effect and their absorp-
almost no supporting structure and
nature w it hin w hat may otherwise be
tion of C02. Planted facades also help
therefore pro vide the simplest method
barren and industrial surroundings. While
with the retention of rainwater after
of installation to both new buildings
climbing plants can be seen as tempo-
heavy rainfall.They reduce inten se local
and existing facades. Plants are grown in
rar y additions to buildings, technological
heat gains experienced in cities and ere-
individual containers and trained across
MCH
390
Details I. Irrigation hose 2. Planted facade 3. Compacted soil 4. Metal container 5. Drainagechannel 6.Yentilated cavity 7. Outer wall with waterproof seal 8. IOmm waterproof base board 9. Stainless steel support structure 10. Polyamide felt substrate I I. Support bracket
I 1
I I
1° I I
I 1
I I
° 1 I I
I I I
1 I
I
I
~ CD ~ - - - -, Modular system with rockwool substrate: Paradise Park Childrens Centre. London.Architect: DSDHA
Modular green wall system
trellises or wires fixed back to the facade. Because plants grown in this manner will
facade. Because of their modular nature, sub-
have a maximum height to which they wi ll grow it is often necessary to distribute many containers across the facade to achieve growth beyond this range. It can take many years to achieve a dense, homogeneous coverage. Planting beds, laid vertically on the facade, allow for full surface coverage. Plants grow horizontally out from the wall rather than vertically up it and this allows for a wider range of plant types to be used. Living wall systems fall into two categories, distinguished by their method of plant cultivation:
strate walls often take on a chequerboard pattern, however it does give great flexibility and allows panels to be replaced individually ifnecessary.
Modular systems Modular systems use cassette elements filled with a soil substrate that plant roots draw nutrients from.The modular units are usually cultivated off site until they reach maturity.These modules can then easily be fixed to a supporting structure on site to complete the
Hydroponic walls Hydroponics is a method of growing plants wit hout the need for a soil substrate.An irrigation system distributes nutrient enriched water droplets across the facade which are absorbed directly by the roots. Hydroponicwalls have a much reduced constructional depth and impose significantly reduced loads on the building facade (around 30kg/m2) when compared to substrate systems. The standard form of construction provides felt pockets in which plants can be individually located. Roots spread radially wit hin the felt and can support plant growth of up to six metres. Horizontal irrigation pipes run along the outer edge of the felt at the to p of the facade.The
Hydroponic green wall system
supply of water is computer controlled to ensure the regularity of operation is in keeping with external conditions.The exact calibration of the system needs to be calculated prior to installation taking into account the facade dimensions, plant types and local climate, to ensure adequate supply of nutrients to all plants. With correct cult ivation and maintenance living walls have a lifespan of around 30 years.
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Modular plant ing unit
MC H
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Environment 05 Active design I: liquid based heating/cooling systems
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Detail s I. Floor mounted fin radiator
2. Convector in floor recess 3.Wall mounted fin radiator 4. Fins 5.Water flows through panels 6. Floor grille 7. Glazed externalwall 8. Metal tray to reflect heat 9.Water flows through pipe 10. Floor I I . Radiator 12. Boiler 13. Pump 14.Thermostat
Liquid based heating systems are provided
as radiation. Radiators are positionedto
mainly by radiators, convectors or under-
maximise convection currents and minimise
floor heating. Commonly used liquid cooling
pattern staining.They can be individually
systems are chilled ceilings, chilled beams and
temperature-regulated with either a manual
related items which are mainly used in office
or thermostatic type valve on a constant
buildings where heat loads from building
temperature circuit or linked on a compen-
occupants and equipment impose cooling
sat ing distribution system, which automati-
requirements for much of the working year
cally varies heat supplied to different facade
even when solargains are minimal.
orientations and adjusts in response to ambient variations.
Radiators Radiator systems pump low-pressure hot water through a pipe circuit, and distrib-
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Fan and passive convectors Fan convectors are used where air needs
ute the heat through radiators which have
to be heatedvery quickly, such as in coun-
a large surface area to radiate and convect
tering downdraughts adjacent to large areas
heat. Heat is generated by boilers, usually
of glazing or above building entrances. Pas-
fired by gas or oil.The pressed steel radiator
sive convectors are more staticand are gen-
which has generally replaced the traditional
erally used where the loads are more stable.
cast iron type, is made from pressed metal
Convectors utilise a constanttemperature
sheet welded together and has become
low-pressure hot water pipe circuit.They
the most commonly used type.They are
are also used in conjunction with mechanical
generally ribbed to encourage convection
ventilat ion systems. Convectors consist of
currents, many have fins on their rear surface
thin metal fins radiatingfrom a central pipe
to enhance performance and panels can
supplied with circulating hot water. The fins
be supplied as single, double or even triple
are enclosed in a metal casing to increase
to match duties required. Most of the heat
the effect of convection, cau sed by the
is given off as convection, the remainder
movement of air around the fins. Convec-
tors can be fioor or wall mounted and, like
fioor surfaces in materials such as stone
ture of the water rises as it fiows through
radiators, they are positioned to maximise
would be cold to the touch.
the panels.The water is pumped back to a refrigeration plant or heat exchanger.
air currents. 'vVhen used in conjunction with glazed walling they are often recessed into the raised fioor. Fan-assisted units distribute
Chilled ceilings Passing air through a building during the
Chilled ceilings are used as an alternative to full air-cooling and are used in conjunction
the air more quickly,but can create noise.
night at outside temperature can help to
with ducted mechanical fresh air ventilation
Convectors are generally controlled by
cool the building structure. When a building
systems.
valves operating in response to temperature
is designed for this strategy the structural
sensors and, because they require less water
soffit is exposed to the occupied zone pro-
than radiator'S, react more quickly to changes
viding a passive cooled ceiling to the space
in temperature if thermostatically monitored.
thereby slowing the rate of rise in inter-
Chilled beams - active and passive These devices are often grouped with
A convector type used in conjunction with
nal resultant temperatures. However, this
chilled ceilings but they are quite different
mechanical ventilation systems is the fan-coil
approach is hard to control and is depend-
in operation. Active chilled beams are sup-
unit, used primarily for cooling.
ant on reliable diurnal temperature differ-
plied directly with treated fresh air to induce
ences during warm summer periods.
added convection across the heat exchanger
Underfloor heating Underfioor heating is another alterna-
surfaces and generally provide greater coolChilled ceilings have been developed
ing capability than a chilled ceiling system.
tive to radiators. Heat is radiated from PVC
to provide a controllable means of achiev-
Passive chilled beams rely on warm room
pipes set into the screed of a concrete slab
ing overhead static cooling.These systems
air from the surrounding volume creating a
or located within the void in a timber fioor.
consist of chilled radiant panels,cooled by a
downward fiow as it is cooled when in con-
Insulation is laid under the pipes to minimise
chilled liquid, which are fixed to ceilings pro-
tact with the beam heat exchanger surface;
heat loss and, in the case of multi-storey
viding cooling by both convection and radia-
they provide considerably less cooling at
buildings, avoid heating of the fioor below.
tion. There are a number of types but gener-
the same density when compared to active
Water in the pipes is kept at a constant
ally chilled water is circulated in very small
beams.With passive beams,the ventilation
temperature of about 50°C, which is only
diameter pipes connected to panels which
air is often provided by an underfioor or dis-
warm to the touch.This system is often used
act as the heat exchanger to the internal
placement system. A chilled liquid, normally
as low-level background heat or where large
space.As cooling is provided, the tempera-
water, cools both types of chilled beam.
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Environment 05 Active design 2: mechanical heating/cooling systems
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All-air system.
Air-water system.
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I. Air handling unit 2. Space being ventilated 3. Fresh air 4. Exhaust air 5. Supply air 6. Return air 7. Supply and return warmed and/or chilled water 8. Induction unit or fan coil unit
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Mechanical vent ilation systems use ducted
cal ventilation,which are as follows:
during the energy conscious nineties due to
air that is heated or cooled either by a cen-
. Constant air volume (CAV) sys-
the waste of energy inherent in coolingthe
tral plant or at the point of use or by a com-
t em, in which the temperature of the air is
air centrally only to re-heat it locally.
bination of thesetwo methods. Mechanical
altered.
vent ilation is used primarily for its ability
. Variable air volume (VAV) system, in which
ing temperaturesto be supplied to different
to provide fresh air to large areas within a
the volume of air delivered is alt ered.
zones. Separate ducts supply heated and
building where natural vent ilation cannot be used successfully.This is often due to the need for closertemperature control, or because of a deep floor plate where natural
The dual duct system allows air at vary-
cooled air, which is mixed at the point of
Constant air volume (CAV) system The constant air volume (CAV) system
delivery in response to room temperature sensors.This enables a much great er degree of control, but it is much more expensive
vent ilation would be less effective, or where
delivers air to a space with no variat ion in
windows cannot be opened due to external
volume regardless of load change.As vari-
much more space in the building services
noise and/or air pollution. Air from a central
ous parts of a building have different heat-
zones.
plant is ducted in prescribed volumes, based
ing and cooling requirements at any given
on either the number of people or the
time, in theor y separat e CAy systems are
than the single duct system and requires
The constant air volume system utilises air-handling units that supply either warm
room thermal load, to where it is needed
required for each zone.This causes problems
or cool air. Some units can supply both hot
around the building. Air conditioning modi-
in large developments with multiple zones
and cold air simultaneously by dividing their
fies the state of the venti lation air, which can
so a central supply system is used with local
supply. One half is warmed and the other
include re-circulated air, primarily changing
temperature adjustment.Traditionally these
cooled, after which they are remixed to
the t emperature and humidity of the ducted
systems relied on the central plant supplying
provide the required temperature. Ducts
air. As is the case with radiat or systems,the
a premixed volume of return air and fresh
supplying different zones can be connected
air t emperature can be modified at the
air treated to a level that coped with the
separately to t he air-handling units,with the
point of delivery. Simplersystems are avail-
highest sensible heat gain in summer or low-
required temperature controlled by damp-
able whereby local air supply units are used
est net heat loss in winter.Re-heat coils in
ers.
which deliver the air directly into the space.
the terminal ducts cat er to local variat ions in load in response to room temperature
There are tw o basic approaches to mechani-
MCH
394
sensors.This type of system fell out of favour
Single duct CAY system
Dual duct CAY system
o
Details I. Pump 2. Cooling tower 3. Heat exchanger 4. Condenser 5. Evaporator 6. Boiler 7. Fan 8. Heatingcoil 9. Cooling coil 10. Filter I I.Water spray 12. Supply air 13. Exhaust air 14. Return air 15. Induction unit or fan coil unit 16. Space beingventilated 17. Air handling unit 18. Solarheat gain 19. Heat loss through fabric.
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nvironment 0 Active design 2: mechanical heating/cooling systems
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Principle ofVAV
Euralille Commercial Centre, Lille, France.Architect: Jean Nouvel.
Variable air volume (!AV) system The variable air volume system (VAV) is
adjust the volume supplied whilst maintaining adequate velocit ies for mixing. Variable speed
Air handling units An air-handling unit draws outside air in
used where the heating and cooling require-
electric fans are used in the central plant to
through a filter using an electric fan, where
ments differ within the same building, or even
maintain constant duct pressures thus ensur-
dust particles are removed. The air is then
within the same treated volumeVAV systems
ingthat terminal units can maintain volume
warmed or cooled to the required tempera-
usea single supply duct distributingair at a
control.
ture for distribution.The temperature and relative humidity of the air can be control-
constanttemperature. It responds to different temperature requirements in different spaces by alt ering the volume of air supplied. For example,the air volume supplied to a
Mechanical ventilation equipment
led by a combination of warming,cooling
Mechanical ventilation equipment con-
and humidifying devices.The air is warmed
sists of an air handling plant and a network
by drawing it through a heating coil,which
space will be increased if the temperature
of supply and extract ductwork.Air is blown
is heated by heating fluid, or through a heat
begins to rise, whilst the reverse occurs for
through supply ducts from the air-handling
recovery device, heated by the return air
dropping temperatures.The system provides
unit to a series of supply grilles or diffusers
stream. To cool the air it is drawn across
local temperature control wit hout the need
and returned via extract grilles or from a
a coolingcoil cooled either by a cooling
either for separate air-handling units, or for
ceiling void.Air that is recovered in extract
fluid, wat er or directly by a refrigerant.The
water to be supplied to terminal units to
ducts which return it backto the air handling
humidity of the air can be controlled by
warm or cool the air.The heating of perim-
unit can be filtered and partially re-circulated
spraying wat er into the air stream to increase
eter spaces can be provided for by a liquid
depending on the system andtime of day or
its humidity, or by de-humidifying it as it is
perimeter heating system. It is important
year. The remainderis discharged to outside.
cooled. Air handling units either are installed
when designing these systems to ensurethat
Air is usually re-circulated becausethe quan-
in a plant room or are self-contained, water-
the blend of fresh air to return air is sufficient
tit y of air required for coolingor heating is
proof package units that are located exter-
to maintain adequate fresh air at a minimum
often several times greater than that required
nally
volume setting for ventilation purposes.
for ventilat ion.
Air supply t o each space is controlled by variable volume terminal units which
MCH
396
VAVsystem
Details I. Pump 2. Cooling tower 3. Heat exchanger 4. Condenser 5. Evaporator 6. Boiler 7. Fan 8. Heating 9. Cooling 10. Filter I I. Water spray 12. Supply air I 3. Exhaust air 14. Retum air 15. Induction unitor fan coil unit 16. Space being ventilated 17.Air handling unit 18. Solar heat gain 19. Heat loss through fabric.
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Heat pumps Heat pumps are used in a wide range of applications.The heat pump is a device t hat makes use of both the evaporat ion and t he condensing stages of a vapour compression
ciency for dr y heat using t he non-hygroscopic type and 65-90% total heat recovery (lat ent and sensible) for the hygroscopic type. . Heat pipes capable of 50-65% efficiency. Run-around recovery consists of a series
cycle.The refrigerant in the cycleabsorbs
of coiled pipeswith water circulatingin them,
the heat when vaporised (evaporator) and
set int o the extract duct, usually near the
releases it when t he gas condenses (con-
exhaust air outlet.The water absorbs heat
denser).These heat pumps can be reversed
from the extract air and releases it into t he
to deliver either heating or coolingto the
supply duct.The t hermal wheel consists of a
same air stream or directly int o the space.
wheel made from metal blades that spins in an enclosed jacket betwe en the supply and
Heat recovery
extract ducts.The wheel absorbs heat from
Heat recovery is an important aspect
the extract duct and releases it to the supply
of low energy design for vent ilation systems.
duct.The same principle applies in the cool-
There are a number of methods of heat
ing mode although wit h less benefit,where
recovery used which generally transfer heat
heat from the warm incoming air stream can
from the return air to the supply stream,
be slight ly pre-cooled by exchanging heat
which are as follows:
wit h the exhaust air from the extract duct. Heat pumps can also be used to recover
· Run around coil, capable of up to 50% effi-
heat from exhaustair; helpingto reduce
ciency
energy costs.They are often used in swim-
· Recuperators or cross-over plate exchang-
ming pool vent ilat ion applications.
l.loyds Building,London. Architect: Richard Rogers Partnership.
ers, capable of up to 65% efficiency · Thermal wheel, capable of up to 80% effi-
MCH
397
Environment 05 Active design 2: mechanical ventilated heating/cooling systems
Details I. Pump 2. Coolingtower 3.Heat exchanger 4. Condenser 5. Evaporator 6. Boiler 7. Fan 8. Heating 9.Cooling 10. Filter I I.Water spray 12. Supply air 13. Exhaust air 14. Return air 15. Induction unit or fan coil unit 16. Space being vent ilated 17.Air handling unit 18. Warmed water supply/return 19. Chilled water supply/return
RWE AG Essen, Germany Architect: Ingenhoven, Overdiek und Partner.
Ducting Air is circulated in ducts of galvanized sheet steel, used because of its ease of fabrication, light weight, smooth internal finish to assist air fiow and is economic. Ducts are usually insulated externally in order to reduce heat loss. or gain. and to prevent condensation forming on the outside of the duct when cold air is circulating. Circular ducts have the least surface areaand the lowest frictional losses, however rectangular section ducts are more commonly used in commercial developments due to the fact that they require less depth when fitted above suspended ceilings and are economic. Square sections perform better than elongated sections; the maximum normally accepted depth/width ratio being 1:3. Flat oval ducts are also used in certain applications as they offer an advantage over rectangular ducts in being ableto handle the same volumes wit h smaller sections due to lower frictional losses. Flatoval ducts are however more expensive to manufacture and require more specialised fabricators than circular or rectangular. The cross-
MCH
398
Lloyds Building,London. Architect: Richard Rogers Partnership.
sectional size of a duct is a balance between volume of air required,pressure drop and air
Package units Package units do not require a network
directly supplied, and distributethe air at the required temperature and volume to the space served.
velocity Smal l volumes of air can be delivered
of ducts.They are essentially air handling units
at high speed or,alternatively, larger amounts
which draw air from outside and either cool
of air can be delivered at lower speeds all
or heat it, releasing the treated air directly t o
above a false ceiling or vertically mounted
wit h the same pressure drop using the same
the space served. Due to its relatively small
concealed or exposed against a wall.They are
duct size.
capacity the package unit is unsuitable for
sometimes concealed below a raised floor
large spaces, since too many units would be
working as part of a floor supply system.
Supply and extract plenums
required.
Induction units
The need for extract ducting can be reduced where the void provided by a suspended ceiling or raised floor is used as a
FCUs can be either horizontally mounted
Fan coil units Fan coil units (FCU) work in conjunc-
Induction units come in a variety of forms although they are less popular nowadays.The
supply or extract plenum. W hen used as a
tion with a central fresh air plant.Generally,
most commonly used units were perimeter
plenum,the ceiling or floor void can house
the fresh air required is treated at a central
mounted, normally part of a perimeter office
air-handling equipment that recirculates air
air handling plant and supplied at a constant
cabinet section.They are supplied wit h high
at the required temperature.Alternatively,
temperature and volume either directly to
velocity centrally treated fresh air which dis-
extract air can be drawn backto the central
the FCU or into the room/space served.
charges via supply nozzles within the units,
plant for treatment. Sometimes light fittings
The FCU is normally provided with cooling
inducting room air from low level to be
are used as air extractsto draw away the
and heatingcoils and an inlet filter for the
drawn across cooling and/or heating coils,
heat they produce.Extracted heat from
return air. The heating coil can somet imes be
then mixing wit h the fresh air and discharging
these fittingscan be recirculated, or exhaust-
an electric coil if low usage is anticipated or
vert ically into the room.
ed from the building as required, which helps
no heating fluid is readily available.The fans
to reducethe direct impact on room heat
inside these units can be speed regulated,
gains due to lighting.
normally by step changes, they simply draw room air in, mix this with fresh air where
MCH
399
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nvironment 05 Active design 3: electrical lighting
Furniture House,Yamanashi Prefecture, Japan.Architect: Shigeru Ban.
Kitakame Canal Museum,Japan. Architect: Kengo Kuma and Associates.
Electrical Lighting. The two main types of electric light
tungsten halogen type. All thesethree lamps run on mains
extremely efficient and lasts approximately 12,000 hours. High-int ensit y discharge lamps have a
source are tungsten filament lamps or incan-
power (house current).The GLS and IStypes
descentlamps, and discharge lamps.
last approximately 1,000 hours, while the
wider range of colour rendering, use much
PAR lamp lasts up t o 2,000 hours.
less electricity and lastlonger than an equiva-
Incandescent filament lamps
Another type called low voltage tungsten
lent tungstenfilament lamp. Mercury vapour
halogen lamps, run off 12volts and require
lamps are used for lightinglarge spaces, such
current through a thin tungsten filament in a
a transformer.They produce sharply direc-
as factories, where colour rendering is not
glass bulb containing either a partial vacuum
tiona beams of light, making them useful for
a determining factor as they have a yellow/
or an inert gas.The filament glows and pro-
illuminat ing displays.They can last up to 4000
blue colour. Metal halide lamps have excellent
duces a mixture of light and heat.W hen an
hours.They are also used for car headlights.
colour rendering and are commonly used in
These lamps produce light by passing a
alltypes of buildings from commercial offices
inert gas such as halogen is used,the lamp runs more efficiently as more of the electri-
Discharge lamps
to public buildings. Both types of lamp last
These lamps work by discharging an
approximat ely 10,000 hours. Compact fluo-
electric current through a gas or vapour in a
rescent lamps,which are used as a substitute
sealed glass tube or bulb,which causes it to
for GLS and are compatible with tungsten
lighting service (GLS) light bulb. It has clear;
glow.These produce more light and less heat
fittings, offer significant energy savings as a direct substit ution for incandescent fittings.
cal power is converted into light rather than heat. The most common lamp is the general coloured or pearl glass and its shape can vary
than a tungsten lamp for the same amount
from the common bulb form to spherical or
of power. The most common type is the fluo-
linear. Some bulbs have their end silvered to
rescent tube, which is filled with low-pressure
reflect light upwards, reducing glare.The bulb
argon and proport ionally small amount of
used for spotlights or floodlights is the int er-
mercury. The tube is coated with a fluo-
lamp and direct light to the point of use.They
nally silvered reflector;or IS lamp. Its charac-
rescent powder;and lengths vary between
are used for both incandescent filament and
teristic shape is designed to reflect light in a
320mm to 2400mm ( 13in to 96in).There
discharge lighting.A huge range of luminaires
particular direction.A bulb with better direc-
is no standardisation in the production of
is available, each suited to it s intended use,
tional focus, due t o a reflector and a lens at
these tubes,and each manufacturer designs
location and method of directing light by dif-
Luminaires Luminaires are used both to hold the
the front, is the parabolic aluminised reflector;
lamps to their own specification.Tubes can
fusion, reflection or absorption. Manufactur-
or PAR lamp, which is particularly suitable for
last up t o 10,000 hours, but their efficiency is
ers' catalogues use polar curves to plot the
spot lights and floodlights. Some lamps have
slightly diminished wit h use.The low-pressure
intensity of light radially around a cross-sec-
dichroic filters in front of the bulb to reduce
sodium discharge lamp is another common
tio n or long-section thro ugh a light fitting.This
the amount of heat projected forward of
type used in many countriesfor road light ing,
helps the design team to understand how
the fitting. PAR lamps are also produced in a
which has a characteristic yellow colour.It is
light from a single fitting will be directed.
MC H
400
International Housing Exhibition, Fukuoka,Japan,Architect: Rem Koolhaas, Office for Metropolitan Architecture,
Ceiling mou nted t ypes Luminaires on ceilings are either pendant
Freshwater Pavilion, Neeltje jans, Holland,Architect:NOX,
hung from the wall on a cantilevered bracket.
advance so as to incorporate cable ways and
Most wall-mounted fittings are surface
access boxes int o the external works.
(hanging), surface mounted or recessed.The
mount ed which can direct light in all direc-
pendant is the most flexible, allowing light to
t ions away from the wall, either directly or by
be thrown up,down or a mixture of both.
reflection, Recessed wall lights have either a
Surface mounted luminaires can direct light
diffuserin front of the lamp or a reflector to
and stairs to be sufficiently illuminated in
to the side or downward. Recessed fittings
avoid glare,
the event of a fire or other emergency. The
throw light downward by concealing the lamp and luminaire behindthe ceiling plane. Pendant luminaires are often used where
Emergency lightin g Emergency lighting allows escape routes
lighting can be permanently illuminated or
Floo r mo unted t ypes Freestanding floor mounted uplighters
switched on automatically by a fail-safe system in the event of a power failure. Both
there is no suspended ceiling, They can be
are often used in offices to provide or sup-
tungsten filament and discharge lamps are
fixed directly from the ceiling or housed in a
plement office lighting. They are generally
used. Power to emergency lighting is normally
track that is attached to the soffit. Huge vari-
better for glare control than ceiling mounted
supplied by batteries charged continuously by
eties of ceiling tracks are available, and some
lights. Energy efficiency is lower with this
the mains using separate circuits. Emergency
incorporate both fluorescent strips and tung-
type of fitting as the light has to be reflected
generators should be used in buildings where
sten filament spotlights in a single length,
from the soffitto illuminate the space,
mains failure can affect life safety and other essential equipment. Batteries are usually
Ceilingfittings are often co-ordinated with low energy mechanical features such as chilled ceilings and beams. Fittings suspended
A recent development in luminaire
housed within plant rooms.
design is the recessed floor type.These have
from a thermally exposed soffit can be
a cover that is strong enough to walk on and
designed to incorporate acoustic absorbent
which is designedto minimise glare when
mat erial t o help address reverberation, Ceil-
looking down at the floor. This type has t o be
ing light fittings can also form part of inte-
capable of dissipating its own heat generated
grated servicing fingers, often usedto service
in use, and as a result the casings are often
exposed soffit areas, incorporating sprinklers,
made from metal alloys with highthermal
air supply, chilled beams and high level electri-
conductivity such as brass.
cal services,
Exterior luminaires Wall mounted types Luminaires on walls can also be pendant,
Exterior lighting utilises all of t he above fixings, Luminaires must be either wat er-
surface mounted or recessed. Pendant fitti ngs
proofed or sheltered from the weather and
are mostly used in conjunction with a track
power supplies must be planned well in MC H
40 I
Environment 05 Active design 4: fuel and water supply
FUEL SUPPLY Natural gas
ways, including coal burning, nuclear and
individual appliances such as lifts. Sometimes
hydro-generation. Electricity is usually pro-
individual distribution boards are provided to
duced as alternating current (AC), which
serve separate areas wit hin a building. Some
is cheaperto produce and transmit than
areas require single-phase, while others will
formed in pocketsbeneath the earth's
direct current (DC), Electricity is transmitted
require three-phase supply.
surface. It is brought to its point of use by
regionally at highvoltage and low current
a network of pipelines. Natural gas has no
except in large countries such as the USA
modified.This is facilitated by a cable-tap
Natural gas is a non-renewable source
The sub-main must be capable of being
smell, so a tiny quantity of odour is added in
where low voltages are used to reduce
system.The four cables of the three-phase
order that dangerous leaks can be detected.
wastage across long distances.The voltage
supply are supported in a metal trunking
Gas is supplied to buildings under pressure
is stepped down at substations for use in
and connections are made with connectors
normally via a single service pipe where the
buildings.
called tap-off units. For heavier loads, or
supply terminates in a stopcockand meter.
Power is distributed from substations as
where it is necessary to make connections
Beyond this point,the gas supply forms part
a three-phase supply. Smaller buildings are
without interrupting the supply. a busbar is
of the building services, and is usually con-
connected to one of these phases (single-
used.This consists of solid conductor rods,
nected directly to the gas-fired boilers.There
phase), whilst largerbuildings are supplied
without insulation, supported in a metal
are design limits for internal pressure drop
wit h all three phases plus an earth (three-
trunking. Connecting units enable leads to be
between the meter and the point of use. In
phase). Smaller installations in buildings have
run off from the conductorsto tap-off boxes
some cases gas pressure is insufficient for
a consumers unit (circuit breakerpanel)
without switching off the current.
the plant needs and special gas boosters are
distributing power to a primary ring circuit.
used to raise the pressureto a satisfactory
Socket outlets (for portable appliances) and
level. Geographical areas that are not served
spurs (for fixed appliances) are connected
by natural gas require large gas tanks that are
to the ring main. Spurs can also be used to
refilled by deliveries.
connect other sockets in order to minimise
rivers or ground wells) is treated, filtered
wiring.
and distributed by a water supply network,
Electricity Electricity is generated in a variety of
MCH
402
In larger installations, a distribution board allocates circuits for lighting, sub-mains and
WATER SUPPLY Fresh wat er (from reservoirs, lakes,
which terminates at the boundary of each property. usually as a single pipe.Beyond that
enVironment 05 Support services I : sanitation and drainage
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Combined dra inage system
D et ails I. Gully to rainwate r pipe 2. Gully from kitchen 3. Soil and vent pipe 4. Inspect ion chamber 5. Building
6.WC
8. Foul water 9. Surface water 10. Property boundary I I. Sewer 12. Foul sewer 13. Surface water sewer
Det ails
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I. Supply to soakaway 2. Drainage opening 3. Drainage out 4. Foundation 5. Hardcore 6.Access cover
7. Combined dr ain
point,the supply forms part of the services
separate parts of the building, or pressurised
determined for the cold water system. If the
installation.A st opcock separat esthe supply
throughout with pressure reducing stati ons
storage cylinder is unable to provide ade-
grid from the individual distribution system.
at intermittent levels to avoid over-pressure
quate pressure to the highest appliance from
at draw off points. Various regulations govern
a gravity supply then pressure boostingwill
the method of maintaining uncontaminated
have to be considered. If hot water is stored
Water distribution within a building is
supplies in buildings. These generally stipulate
in calorifiers, the distance from draw off
either gravity fed from storage tanks at or
the method of connection to appliances and
points is minimised to reduce the cold wat er
closeto the roof of the building, from a pres-
draw off points with an emphasis on protect-
run-off from the pipe. Circulating pumps
sure booster pump set at a lower level or by
ing against reverse flow.
are used to maintain high temperatures at all
Cold water distribution
direct mains supply.Although water storage can require a large space, tanks provide a
points on the network via flow and return
Hot water storage and distribution
pipes.Trace heating is used to maintain tem-
limited reserve in the event of an interrup-
The choice of hot wat er system is
tion to the mains supply. Traditionally this is
based on the location and density of draw
a single hot wat er pipe and is sometimes
based on a capacity relating to 24 hours of
off points, the size and configuration of the
used in place of runninga flow and return
predicted consumption. Cold water tanks are
building and the location of boiler plant.
network.
generally made from galvanized mild steel
Large office buildings with fairly big distances
Hot wat er can be generated by either
or glass reinforced plastic (GRP); they are
between closest and farthest draw off points
primary hot water from a boiler; by direct gas
normally insulated to prevent condensation
are generally suit ed to localised wat er heat-
fired storage heaters, by an electric immer-
forming on the outside face. Supply to the
ers, whereas buildings such as hotels are
sion heater or locally via electric or gas hot
tanks is controlled by a float-operated ball
more suited to centralised boiler powered
water heaters. In some cases, it is preferable
valve with overflow pipe to protect from
hot water calorifiers.
to provide hot water from a storage tank
overfilling the tanks. In tall buildings where
The method of distribution is determined
perature on remote draw-off points fed by
that is fed directly from the mains water sup-
the water pressure in the supply pipe is too
by the length of run-off from the point of
ply rather than from a cold water tank. This
low to achieve adequate pressure at the
heatingthe water to the point of use. Hot
system is unvented and requires a series of
draw off points, water can be pumped.This
wat er can be fed by gravity or pressurised,
valves to ensure that the wat er pressure and
can fill a series of smaller tanks, each serving
this will normally depend on the strategy
temperature are closely controlled. MCH
403
Drainage below ground
Ladder steps are provided if the chamber
at or below ground level.They are manufac-
is deeper than approximately 600mm (2ft).
tured as complete units prior to installation
cycle. Drainage can be provided by a sepa-
Where a pipe runs below a building and an
on site and consist of a series of chambers
rate surface water (storm water) and foul
inspection chamber is required, special meas-
which separate solid from liquid waste. The
(sanitary) drainage system, or combined so
ures, in particular double sealed chamber
liquid waste is allowed to leach back into
that rainwater is drained with the foul water.
covers, are taken to prevent foul air escaping.
the soil through a series of perforated pipes
In some areas,particularly towns, the sepa-
Not all pipe intersections require inspection
called a 'leaching field'. The solid waste
Drainage is the second half of the supply
rate arrangement is preferred so that during
chambers. An alternative is to provide suf-
is periodically emptied into tankers and
storms rainwater does not overload the
ficient rodding points along the length of the
removed for off-site treatment.
drainage system, preventing the discharge of
drainage run.
foul water from buildings. Underground drainage is laid to falls in
Pipework below ground consists of a series of pipe lengths with a spigot at one
Soakaways (drywells) These are a method of providing surface
straight lines to allow for ease of cleaning by
end and a socket at the other. The pipes slot
water drainage directly to permeable ground
rodding. Access points are provided either
into one another, and are sealed with rubber
adjacent to the building. Soakaways are used
where there is a change of direction or
rings. Sometimes separate sleeves are used
in rural areas where there is no benefit in
where pipes join, as blockage tends to occur
to connect pipes instead of sockets.The
draining away rainwater into the sewer sys-
at these points. Rodding eyes or inspection
rubber rings also provide a degree of fiex-
tem. They consist of a large pit into which
chambers are provided for this purpose.
ibility for movement. Pipes are made from
the surface water drain discharges, permeat-
Inspection chambers are also provided along
vitreous clay, concrete, plastic (UPVC) and
ing the rainwater into the surrounding soil.
the length of the pipework. They consist of
cast iron. Pipes are laid in trenches on a well-
The most common type is a concrete tank
a brick, plastic or concrete lined box. The
compacted surface. Concrete is sometimes
made from a set of stacked rings. Simpler
top is sealed with a removable cover.The
used depending on the local ground load-
versions consist of a pit filled with hardcore
upper halves of the pipes in the chamber
ing conditions.They are enclosed in gravel
(gravel) that prevents it from collapsing,
are cut away to provide access for clean-
wherever excessive movement is expected
whilst allowing the water to drain away.
ing by rodding.The connecting pipes in the
and rocker pipes, short lengths of pipe with
chamber do not need to be at the same
connections at both ends, are used to allow
level.This allows pipework to follow levels
movement to occur.
and gradients which suit other parts of the drainage layout and meet at different levels. The lowest level at which the water runs is known as the invert level of the manhole.
MCH
404
Sanitation and drainage above ground Water in a building is drained as either
Septic tanks Septic tanks are used where there is no local sewer system.These can be set either
soil or waste. Both are drained either separately in a two-pipe system or together in a single-pipe system.The drainage is usually
Combined drainage system
Separate drainage system
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Details I,WC 2.Wash basins 3. Urinals 4. Showers 5. Soil pipe (mayrequire additional vent pipe) 6.Waste pipe (mayrequire additional vent pipe) 7. Soil and vent pipe
to the sanitary appliance is fitted with a separate vent pipe known as an anti-siphon installed and connected to the below ground
vertical pipes, leaving an air gap in the mid-
drainage from inside the building to avoid
dle. In horizontally laid pipes,the water runs
the pipes freezing and to avoid multiple
down the bottom or invert of the pipe due
street sewer connections.
to a shallow fall.The air inside the pipework
pipe.
Rainwater There are a number of rainwater sys-
Water closets (WCs) and urinals are
is designed to remain at atmospheric pres-
tems in use today, the choice of which is
drained to a soil pipe. Sinks, basins, baths and
sure to equalise air pressures on either side
based on the type of areas being drained.
showers are drained to a waste pipe. Rain-
of traps. If the pipe bore is filled with water
Large areas where space for high level col-
water is drained separately Below ground,
then air cannot balance the system, causing
lection rainwater pipework is limited can
the soil and 'waste pipes combine as foul
traps to pull due to the siphon effect, or
be drained using siphonic drainage systems.
water drains. Rainwater either drains into
blow through their water seal due to over-
These systems are designed to create a
separate surface water drains or it joins with
pressure. Consequently, pipes are designed
suction pressure within small-bore horizon-
the foul water via a special trap forming a
to be large enough to accommodate a per-
tal rainwater pipework and use specially
combined system.These pipes run below
centage of air and are ventilated to atmos-
designed outlets. Large glass roofs are often
ground to the main sewer. In areas not
phere close to the sewer outfall and at the
drained by fiat channel systems that have
served by a sewer network, a septic system
top end of the drain stacks.
special tapering outlets to cope with the
can be installed for soil and wastewater treatment. Air from these pipes is prevented from
large fiow rates needed to drain the roof
Single-pipe system This system, also called the single stack
efficiently. Insulation is applied to rainwater pipework where it passes within internal
entering the building using traps fitted to
system, combines the soil and waste pipes.
each sanitary and waste appliance. Pipes
Each sanitary and waste appliance is con-
slope downward to the sewer, since they
nected to a single pipe, one above the other
ground into either a combined or a sepa-
work entirely by gravity Pumps are only
in a stack.The pipe used is generally larger
rate drain, which is then connected to the
occasionally used where adequate falls can-
than in the two-pipe system, helping to avoid
combined foul and surface water sewer or a
not be provided. For this reason, pipes with
pressure fiuctuations that might cause the
surface water only sewer. In both cases, the
smooth internal bores are used to reduce
traps to lose their seal. The use of a straight
connection is made via a vented intercepting
friction. Falls in soil pipes below ground are
stack,that is,without bends above ground
trap. Rainwater is sometimes collected into
normally around I :60, depending upon loca-
level, ensures a controlled fiow of soil and
storage tanks for reuse in irrigation appli-
tion, design fiow rate and size.
waste, allowing air to move freely in the pipe.
cations or as a supplement to grey water
Lengths of waste pipes from appliances to
systems. Bypass pipes are needed to avoid
the stack are limited to approximately two
overfilling storage tanks.
Balancing the system Water flows down the inside surface of
areas to avoid condensation. Rainwater is generally collected below
metres (6ft). Beyond this distance, the trap
MCH
405
nvironment
05
Support services 2: fire control
Fire prevention Most fires are caused by electrical problems. Since electrical cabling and installations
sprayed with a fire resistant material such as
and prevention to be considered before the
vermiculite.
design is finalised andthus forms an integral
Buildings are usually divided into fire
are usually hidden from view,an early detec-
compartments, which are used to limit the
tion system is essential. Medium and larger
volume in which a fire can spread. Although
sized buildings are required to install an elec-
separate floors are isolated, shafts that pass
part of the building when complete.
Fire escapes The most important function of fire
trically operated fire information panel that
between them, such as service risers, require
escapes isto ensure that people can leave
will indicate the position of any fire within
fire breaks either at each floor level to
the building quickly and safely. Individual
the building. Once a fire has started it must
ensure the integrity of the compartments or
compartments have protected areas that
not be allowed to spread unchecked. For this
the shafts are enclosed by suitable fire rated
allow people to escape without coming into
reason the choice of materials inside a build-
wallsand all penetrations are fire stopped.
contact with either smoke or flames once
ing isextremely important both in terms of
Fire breaks are constructed from a fire
they have reached these areas. Protected
their combustibility, spread of flame across
retardant material such as cement mortar
areas usually discharge to the outside of the
their surface and the production of poison-
or mineral wool quilt.Tostop fire spread-
building at ground level.The usual minimum
ous fumes.
ing between buildings, external walls are
requirement for a protected area is 30 min-
Fire protection Structural walls, columns, floors and staircase enclosures must be furnished with
protected with fire resistant applications or
utes.This is judgedto be the maximum time
utilise specifically designed dividing walls.
required to evacuate everyone from a build-
Recently, some of the prescriptive rules for fire protection are slowly being tempered
ing. Legislation in most countries for stair widths, door widths, and corridor widths is
a fire resistant outer layer in order to remain
by fire engineering studies undertaken at
based on occupantflow rates that will clear
stable during a fire, for between one and
the design stage.These involve an overall fire
everyone pasta given point within tw o
four hours,depending on the component.
protection strategy that considers both the
minutes. Emergency lighting and signs are
Concrete naturally has a high fire resist-
building structure andthe means of escape
provided to ensurethat this evacuation can
ance and consequently requires no further
together and sometimes involves some com-
occur even during a power failure.
protection. Steel structures are encased in
puter modelling or testing. Each study allows
concrete, covered in a fire resistant board or
alternative combinations of fire protection
MCH
406
Fire detection The provision of fire detection equipment varies with size and type of building.
which must be adhered to, that are based on fire-fighting experience. An essential aspect of fire fighting is
Break-glass units are the most common
to provide access for emergency vehicles.
types of manual alarm where occupants can
Similarly, within a building, hose reels and
activate the fire alarm system. In addition,
portable fire extinguishers are provided as
automatic smoke detectors or heat detec-
a manual first aid means of controlling fire
tors are installed to initiate alarms.Tall spaces
spread.Automatic sprinkler systems are
have beam detectors where the presence of
sometimes used in buildings;these are also
smoke or fire might otherwise go unnoticed.
for controlling the spread of fire and are
Buildings with large fire compartments tend
regarded as a first aid. The latest generation
to utilise special heat detectors, which close
of sprinkler releases a mist or fog rather than
fire shutters when activated.The strategy for
spraying large quantities of water, however
evacuation forms an important part of the
large storage tanks or fail-safe water supplies
planning for detection and alarm signalling in
are still required. Such systems are designed
the event of a fire. Phased evacuation build-
to control fires while people escape from
ings require addressable voice alarm systems
the building rather than extinguishing the fire
and most large capacity buildings need
and they are often isolated by the fire fighters
stages in alarm signallingto confirm whether
when they arrive.
it is necessary to evacuate the building.
the interior, smoke clearance for each compartment should be facilitated through cross ventilation or by mechanical means.
In larger structures, either dry or wet risers are provided to allow the hoses used
Fire fighting Sufficient access and facilities must be
by fire fighters to be connected to a water supply within the building. In taller buildings,
designed into all buildings so that safety for
whose height makes access by ladder unfea-
fire fighters can be provided when tackling
sible, fire fighting lifts and stairs are provided.
a fire.There are extensive prescriptive rules,
In order for fire fighters to reach all parts of
MCH
407
Environment 05 Support services 3: maintenance and cleaning
Cleaning gant ry allowing underside of roof to be cleaned and maintained without cleaning platform from below. B8 offices . Daimler Chrysler Projekt, Potsdamer Platz, Berlin.Architect: Richard Rogers Partnership.
Roof-mounted facade cleaning systems W it h the increased use of metal, glass
systems mounted at roof level, wit h larger
roof terrace.The davit is lifted into position,
buildings having a mixture of these systems
usually by a person pulling it up with a rope
on a single roof.
secured to the t op ofthe post.The arm of the davit can be swung outward once it is
and composite materials in facade design there has been a greater requirement for cleaning and maintenance. Building facades
Davit systems A davit is a jib or scaffold-shaped frame
fixed in place. Cables, secured to the end of the davit arm before it is lifted into position,
30 years ago were detailed with low levels
from which a cleaning cradle is hung.A single
are lowered down the facade to be attached
of maintenance envisaged, with the use of
cleaning cradle, holding one or two persons,
to the cleaning cradle below, at the base of
brick, concrete, stone and timber dominat-
is usually hung on cables from a davit at each
the facade.The cradles usually have wheels
ing architectural design. Facades would be
end of the cradle. Davits are moveableand
which enablethem to be moved t o suit
cleaned only rarely; with details that would
when in use are secured t o bases in fixed
each new pick-up position for the davits as
weat her well with the passage of time.Wi n-
positions near the roof edge. Davits are very
they are moved to each new fixing point on
dows in masonry walls were detailedto be
useful for roofs where the permanent visual
the roof.The cables are connected to the
openable, partly to admit fresh air for ven-
presence of a monorail or trolley system is
cradle, allowing it to be raised up the facade.
tilation and partly for cleaning access.W ith
not the preferred solution to facade main-
The cradle is fitted with an electric winding
the increased use of sealed facades without
tenance.
mechanism and rubber fenders to avoid
openable windows camean increased requirementfor cleaning equipment.
Davits are usually made of mild steel or aluminium tube and are moved with wheels
direct contact with the facade.There is no winding mechanism at the level of the davit;
at their base.This makes them sufficiently
whose function is to support the cables only.
facades (discussed In Modern Construction
lightweight and mobile to be handled by
The electrical power supply for the cradle
Facades) are often provided in the form
one or two people when they are moved
motors is from points either at roof level
of walkways set at each floor level. Most
into position and fixed for use. Davits are
or at the base of the facade, supplied to
Facade cleaning systems for twin wall
systems, however; are roof-mount ed and
usually dropped into position onto a set of
the cradle by a power cable. In the event of
are required to be integrated into the roof
bolts projecting up from the roof surface,
a power supply failure, a manual system in
design, usually with a minimum of visible
typically as either plinths in the form of short
the winch allows the cradles to be lowered
equipment.These roof-mounted types are
columns, or as a recessed box below the
to the groundV arious proprietar y systems
discussed here. Most facades are cleaned
level of the roof finishes where the bolts are
of winch motors and lifting equipment are
with either davits, monorails or trolley
concealed from view, as on an accessible
available, all with different safety features.
MCH
408
Details I. Cleaning cradle 2. Motor and counterweight 3. Hydraulically operated arm 4. Steel cable 5. External wall parapet 6. Roof surface 7.W heels or guide rails
Above andbelow: Cleaning equipment. l.loyds Building,London. Architect: Richard Rogers Partnership
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Cleaning equipment on this building has been specially designed and integrated into the overall architectural aesthetic being highly visible at all times from the surrounding city streets
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MCH
409
Envlro nmen 05 Support services 3: maintenance and cleaning
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Plan I:50 Davit supportingcradle in two positions
Section I:50 Davit support ing cradle in two positions
Elevation 1:50 and 3-D view of typical c1aning cradle
When one vertical strip of facade is cleaned by a cradlethat is raised and lowered from a pair of davits, the cradle is moved to its next position by descending to its lowest level and disconnecting the cables. The davits are then unbolted and lowered from their bases before beingmoved to the adjacent base positions for re-connection. While this is a relatively slow process involving erecting davits, setting up the cables and cradle, then disconnecting the parts and movingthe davits again, this method avoids a permanentand visible cleaning system being mounted on the roof.The davit system is most commonly used where the roof is used as an accessible roof terrace,or garden, and where a permanent cleaning system would not be visually desirable.
Monorails In the monorail system, a continuous single rail is fixed at roof level, from which a cleaning cradle is hungfrom a cable at each 3-D views of typical cleaning cradle on facade
MCH
410
end.The monorail is set around SOOmm
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===-Section I:I00 and I:50 Monorail supporting cradle from cantilevered brackets! beam
Section I:I00 and I:50 Davits supporting cradle
beyond the edge of the roof to allow the
connected to the cleaning cradle. which is set
cradle to hang slight ly forward of the facade,
at the bottom of the facade.As each vertical
typically on brackets cantilevered from the
strip of facade is cleaned, the cradle is moved
roof structure as shown in (A).The monorail
along the facade. usually when it is at roof
is a visually strong elementthat is integrat ed
level,just below the level of the monorail.
into the overall design for the edge of the
W hen manually operated,the cradle can be
roof.An alternative to cantilevered fixing
moved when at the bott om of the facade if
brackets is to cantilever the edge ofthe roof
maintenance personnel are assisting at roof
out by around SOOmm as shown in (B).The
level.The monorail offers a visually discreet
rail is usually made from mild steel which is
method of providing a permanently fixed
painted or enclosed in a decorat ive metal
cleaning system at roof level.
cover, usually in folded aluminium sheet.
Section NTS cleaningwith hamess on a platform
W here the monorail is hungfrom t he
W here cantilevered support arms are used
underside of a balcony or slab soffit, the
t hese can be castings or standard struc-
monorail can be concealed with cladding
tural steel sectionsto suit the design.The
panels set on either side of the rail. From
monorail,set horizontally, is usually formed
below. only a single continuous groove is
as a channel-shaped section that allows a
visible.A gap of around 20mm is provided
pair of wheels to run inside the rail.Sets of
between the monorail and the adjacent
wheels are operated either by sliding the
panel to allow for movement of the monorail
cleaning cradle beneath manually, or under
itself when in use.This joint is either left open
electrical power for larger installations. As
or closed with a flexible seal,typically EPDM
with the davit system, cables are connected
sheet.
from wheeled pulleys which travel inside the monorail.The cables are lowered down and
Cleaning cradle on glazed facade
MCH
411
Elevation I :200Trolley supporting cradle
Elevation I: 100Trolley on verticallyset rails
(Above).Cleaning cradle on trolley around Swiss Re building,London. Architect:Foster and Partn ers
Elevation I:200Trolleysupporting cradle
Trolley systems W here a facade is required to be
lowered to bring the cradle in and out from
well suited to being mounted on sloping or
cleaned from a roof which is either slop-
the facade and to bring it to rest at roof level.
curved roofs where they climb steep slopes,
ing, or has a stepped profile in elevation,
The trolley itselfhouses the motors for both
typically up to around 45°.
a horizontal monorail is a much less
moving the equipment along its rails, moving
practical solution for supporting clean-
the arms, and raising and lowering the cradle
the cradle can be offset from its supporting
ing cradles. Davits are usually difficultto
itselfThe trolley is usually controlled from
cables by the use of counterweights attached
handle on sloping roofs.Trolley systems
within the cradle, allowing it to move both
to the cleaning cradle.The cradle can be
are better adapted to reaching facades
vert ically and horizontally.
from a sloping roof and where the facade
This system is not usually suit ed to
W here facades step in at a lower level,
moved by an arm fixed directly to the supporting cables.As the arm moves from a
itselfis of complex geometry. Trolleys
roofs which are fully accessible to build-
vert ical position to the horizontal, the cradle
are typically mounted on wheels and are
ing users due to the presence of rails, or a
swingsaway from it s cable.The movement
secured to a continuous track, which may
dedicated path, as well as the visual presence
is balanced by a counterweight at the other
be beneath the trolley, as roof-mounted
of the trolley itself. As the trolley is control-
end of the arm which keepsthe cradle level
rails, or may be set verti cally.The trolley
led remotely, safety at roof level is a critical
and stable.This method is useful in facades
usually has arms which project out over
consideration.W here roofs are required to
which either step outwards as they rise up
the edge of the roof which support a
be accessible, rails are mounted above the
or are inclined outwards through their height.
cleaning cradle from cables fixed to the
roof, but their dominant appearance may
The mixture of a trolley system and cradles
ends of the arms.The arms are some-
deter this solut ion in practice.W here the
allows complex facade and roof forms to be
times telescopic (hydraulically operated)
trolley can be seen from below, it is usu-
cleaned and maintained from a single clean-
in order to reach either the facade or;for
ally concealed behind a screen or in a small
ing cradle.W ith facade and roofs of complex
example, solar shading panels in front of
enclosure, allowing it to be protected from
geometry, the trolley rails can be concealed
the facade. The arms are usually raised or
the effects of the weather. Trolley systems are
in a gutter at roof level where facade and
MCH
412
Elevation I:500Trolley with reach over adjacent facades
- --==O:::'==-'il , I Left and right: Elevation I:200 Trolley with reach over adjacent facades
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tiM roof form a single and continuous form. In the example above a trolley is set behind a parapet formed by solarcontrol louvres. It is set on a track that forms a conPlan I:50 Cradles hanging from trolley
tinuous loop to suit the shape of the building. As the trolley moves around its circuit it is ableto reach all parts of the facade.The trolley is ableto reach the facades with telescopic armsthat can be adjusted both in length and heightto suit the facade being cleaned. A single trolley is usually provided for a single building, but more than one may be required, working on t he same track,to suit different facade geometries beneath. Not all largescale trolleys require tracks to restrain them. Trolleys with wheels that move on a raised portion of roof deck are also used.
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Section I:200 Cradles hanging from trolley and monorail
MCH
413
Vert ical section Traction lift
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There are two generic types of elevators: traction,where the elevator car is suspended on cables with counterweights,and hydraulic, where the elevator car is fixed on a ram which is sunkinto a shaft. In both cases the
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are attached to the inside of an elevator shaft or; in the case of open wall-climber
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elevators, directly to the edge of fioorstructures.lt iscommon in tall buildings to use fast elevatorsthat stop every ten fioors. Intermediate floors are accessed from sepa-
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rate elevators that run between the fast
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The type and number of elevators for any installation isestablished by the following I--
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· Approximate passenger load · Maximum acceptable waiting time · Number of persons each car will carry · Elevator speed f--
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· Expected passengerload at peaktimes Elevator cars consist of metal frames clad with solid or transparent panels. Doors to the elevator cars can be single or double,sliding on either one or both sides of an opening. Width restrictions, particularly where elevators are set side by side, may meanthat doors are set off-centre to the
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Section and plan details I. Lift motor room 2. Guide rail 3. Elevator car 4. Cable 5. Counterweight 6. Elevator pit 7. Enclosing wall 8. Doors to landing set into enclosing wall at each level 9. Doors to car IO. Doors to landing I I. Single hydraulic piston 12.Telescopic hydraulic pistons as altemative to single piston 13. Piston cylinder well 14.Vent to outside 15. Car deck 16. Lift well 17.Access panel/ vent Horizontal section Traction lift
MCH
414
At each level served there are elevator landing doors, which can be solid or transparent.These doors open only when engaged by the elevatorcar doors. When
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the elevator is in an open shaft there is a
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need to protect people on each landing
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from the moving parts of the elevatormechanism. In this case, each floor is provided
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with landing screens which are incorporated
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elevatoris in an enclosed shaft the risk of fire spread from floor to floor must be taken into account. In such a case, the elevator landing doors may need to be fire resistant.
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Call buttons are located on each floor In larger installations, calls are registered by the
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control gearand automatically dealt with in sequence. Banks of elevators have co-ordinated control systems that respond to calls in a given sequence.
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Hydraulic elevators can carry a maximum of aroundthirteen passengers. In theory,there is no limit to what a traction
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elevatorcan carry. For cars carrying up to
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thirteen people the same size well can be used for both traction and hydraulic elevators.An eight-person elevatoris usually the
Vertical section Hydrauliclift
smallest which can comfortably admit a wheelchair.The minimum door width is usu-
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Horizontal section Hydraulic lift
ELEVATOR SIZE
SHAFT SIZE (width x depth)
CAR SIZE (width x depth)
4 person
I 350 x 1500mm
1000 x 900mm
(3ft 3in x 3ft)
5 person
I800 x I 600mm
(5ft lOin x 5ft 3in)
1100 x 950mm
(3ft 7in x 3ft Iin)
8 person
1800 x 2100mm
(5ft lOin x 7ft lOin)
1100 x 1400mm
(3 ft 7in x 4ft 7in)
10 person
1900 x 2300mm
(6ft 3in x 7ft 6in)
I 350 x 1400mm
(4ft 6in x 4ft 7in)
13 person
(4ft 6in x 5ft Oin)
2000 x 2300mm
(6ft 6in x 7ft 6in)
I600 x 1400mm
(5ft 3in x 4 ft 7in)
16 person
2600 x 2300mm
(8ft 6in x 7ft 6in)
1950 x 1400mm
(6ft Sin x 4ft 7in)
21 person
2600 x 2600mm
(8ft 6in x 8ft 6in)
1950 x 1750mm
(6ft Sin x 5ft 9in)
MCH
415
Environment
05
Support services
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Above. l.loyds Registry of Shipping Building, London. Architect: Richard RogersPartnership. Below. 88Wood Street, London. Architect: Richard Rogers Partnership.
Traction elevators are electrically powered.
t he cars.Th ese are usually locat ed at th e t op
Cables, running over pulleys and balanced
of the shaft, adjacent t o t he over run.T he
by counterweights in order t o minimise t he
motor room can also be positioned t o o ne
effo rts of t he elevator motor; suppo rt cars.
side of th e elevator pit at th e bottom of th e
Bot h car and co unterweight move in vert i-
shaft, but th is requires more sophisticate d
cal steel guide rails.Tractio n elevators have
cabling. Mot or rooms require vent ilat ion
advantages over hydraulic elevato rs w it h
because of heat generate d by th e machiner y.
their higher speed and hardw earing qualities.
A pit is located at th e bottom of th e
Speeds vary fro m 0.5 met res per second for
elevato r shaft. It is usually abo ut t wo met res
smaller installation s to 6.0 to 7.0 metres per
deeper th an th e low est floor served in
second for t all buildings. Traction elevators have an over-ru n space at th e t o p of th e shaft.Th is protects
vent ed t o t he outside to ensure t hat air is
anyone working o n t op of t he elevator
dr aw n up t he shaft and out of t he build ing in
sho uld th e car travel to th e t op floo r acci-
th e event of fire.
dentally.Th e overrun also allows cables t o run over the pulley t o th e motor.Th e overrun space also accommodates t he cable pulleys. Moto r rooms house th e elevator motors and ancillary equipment th at drives
MCH
41 6
ord er t o accommo dat e the underside of t he elevator car.The t op of t he elevator shaft is
Details I . Clear t oughened glass 2. Roller guides 3. CHS (steel tube) framing support ing 'structu ral deck' of lift car 4. Lightin g trough 5. Metal plate suppo rting light fitt ings 6. Reflector luminaire 7. Extract fan 8. Metal access panel 9. Bolt fixed glass enclosure 10. A ngled dow nlight ers I I . Flexible mild steel electrical cond uits 12. Removable maintenance platform hung from steel tube frame 13.Floor finish
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14 Lift car guides 15. Bolt fixed glass enclo sure I 6. Suppo r t fram e to car 17. Steel frame t o lift doors o n landing 18. Frameless glass do or s 19. Nylon guides 20. St ainless steel balustrade and handr ail 21. C all button panel 22. Extract gr ille
A hydraulic elevat or consists of a piston
are also useful where an overrun cannot
cylinder set into a well beneath t he elevator
be accom modated easily at the top of t he
pit which acco mmo dates the unde rside of
elevator shaft.
the elevator car at th e lowest floo r level.The piston can be a single or telescopic t ube . Ifit
Verti cal sect io n
The machinery room can be independent of the e levato r shaft, and may be locate d
is a single tube,th e well must be deep. The
up to five metres away. Machine roo ms are
hydraulic piston is fixed to th e bottom of
smaller than th ose of traction elevato rs, and
t he shaft and con nected to the elevator car.
contain pumps. motors. fluid storage tanks
The ram is activate d by hydraulic o il which
and control equipme nt. Machinery room s
is forced into t he cylinder well unde r high
require ventilat ion due t o heat generate d
pressure. which th en moves the elevator car.
by the eq uipment. Hydraulic elevators have
Hydraulic elevator mechanisms are suited
an overr un at t he top of the elevato r to
to installations serving up to five floor s.
prot ect anyone wo rking on th e t op of the
They are usually slower th an t raction eleva-
car, in case it accident ally rises t o the top of
tors, with speeds ranging from 0.63 to 1.00
the shaft. Like t raction elevators,the top of
met res per second.The motor room can
t he shaft is extern allyvent ed to ensure that
be located a short distance away from th e
air is drawn up and o ut of th e building in th e
elevator shaft, rather th an next t o it, either
event of fi re .
Horizonta l sectio n
at th e bottom or th e top, wh ich is an advantage in small buildings. Hydraulic elevators
Ver ti cal secticin
MCH
417
FUTURE A future for building constnuction 2 3
Folded glazing Metal solar shading: louvres and mesh Triangular panels for twisted facades
4
Twisted panels with flat glassfor twisted facades
5
Moving shading panels
6
Precast concrete panels for facades of complex geometry
7
Glazing systems with integral solar shading
8 9
Stick glazing for doub le facades Shingled glazing for facades of complex
geometry 10 Variable concrete panels for solar shading I I Structural facades of comp lex geometry 12 Facade with integrated furnit ure
MCH_ 4 19
Future 06 A future for building construction
Fumiture House, Yamanashi
and which seems set to transform the design
alloy frames covered with an aluminium alloy
of structures and cladding is in the useof
sheetto form a 'semi monocoque' in which
This example of innovative construction uses
technology from other fields. In particular,
the structure and enclosure are separate but
a system of factory-fabricated fumiture units
the use of stressed skin technologyfrom the
work together in composite action. They
which extend from floor to ceiling.These
aircraft industry andthe use of car industry-
provide structures that are much stronger
units are used both asstructural elements
based component technologyare being used
and lighterthan those traditionally used in
to support the timber roof deck andto
in structural design.
the building industry. They are more expen-
Prefecture, Japan. Shigeru Ban.
organise the intemal spaces. The high quality of the off-site fabrication method resulted in the building being assembled on site as a kit of parts. Little material is wasted on site.
sive to build than current building structures,
Stressed skin airframes in 'thin' construction A current development in 'thin' exter-
but are much more economical in the use of material. In the building industry, semi monocoques have been used in plywood
unlikethe highwastage associated with site-
nal walls isthe use of panels that integrate
construction to make floor panels and roof
based construction. Fumiture units are either
structural support, enclosure andthe build-
decks.
A recent example of this form of con-
700mm wide for cupboards or 4S0mm wide
ing environment control system and house
for shelving. Both units are 900mm wide and
the mechanical and electrical installations
struction isthe Mini-House in Tokyo, Japan
2.4 metres high.
that are usually set in ceiling and floor voids.
by Yoshiharu Tsukamoto and Momoyo
These 'stressed skin' structures for aircraft
Kaijima. This innovative construction is built
The use of technology from other fields
were developed by that industryduring the
from a light-gauge steel structural system.
1930s to build airframes. The structure, a
The houseis built from partially prefabri-
A future for structural elements will
cage-like frame, is combined structurally with
cated wall and floor units which are assem-
the metal skin to provide a single structural
bled wit hout the use of columns or beams.
along with 'thin' and 'layered' building enve-
form. Everything in the aircraft's body forms
The walls are made from steel channels set
lopes as introduced in the Walls chapter.
an integral part of its structure. Most aircraft
at SOOmm centres. Panels are 8 metres high
An area where change is already happening
structures, called airframes, usealuminium
and 2.5 metres wide, fixed directly to the
be in their application to and development
MCH_ 420
foundations. Floor sections are 4.5 metres
frame, chassis and mechanical components.
increased awareness of lifecycle costings and
long, SOOmm wide and IOOmm deep. No
This is becoming possible due to changing
the design life of components and assem-
addit ional finishes such asdry lining (drywall)
manufacturing techniquesof digital fabrica-
blies. Different components will have a more
were used in this building.
tion. Three dimensionally curved cladding
clearly defined design life, in line with other
panels can be manufactured with computer
industrial products. An idea that is currently
software that can detenmine co-ordinates
emerging is that of cladding as a single 'car-
for points across the panel, allowing ever
rier system' where a facade is assembled as
Car industry-based components in 'layered' construction In parallel with the aircraft industry,
more complex shapes to be usedwith
a kit of parts with a predetenmined range
the car industry is moving awayfrom the
greater precision. The software used for
of possible uses. Different 'add-on' compo-
semi-monocoques of car bodies and light
this work also influencesthe design process
nents could be added, swapped or moved
chassis. The car industryis exploring an idea
itself three-dimensional modelling allows
about as needed. The cladding system would
where the 'core' element of a car can have a
rapid prototypes to be made. This compu-
comprise a primary 'support frame' onto
series of pieces added on to change it from
ter-based technique also allows the rapid
which is added a series of separate 'sub-
people-mover to pick-up to open-t op car
digitising of prototype models. Increased
systems' providing weatherproofing, ventila-
by changing only a few components. The
useof more 'flexible' manufacturing equip-
tion, solar control and so on. Structures and
Opel MAXX was developed originally as
ment e.g. robots as now used by leading
envelopes could then adapt more easily
a modular car in Genmany. The aim was
cladding systems manufacturers means that
to changes in the way a building is used by
to produce a small car for city use with an
repetitive production is no longer a con-
adding or replacing sub-systems rather than
aluminium frame, to which different bodies
straining factor in making the manufacture
rebuilding t he entire facade, as often hap-
can be attached, fonming a parallel wit h lay-
of panels economically viable. This allows
pens wit h office buildings. Changing these
ered facades. Options would include a con-
different design optionst o be quickly and
sub-systems would be considerably cheaper
ventional five-door hatchback. a two -door
reliably costed by manufacturers at an early
than full replacement of the facade, but the
coupe, a convertible, a pick-up, off-reader;
stage. These changes have brought about
initial capital cost would be higher than that
van and taxi. The bodies would clip onto the
of a conventio nal system.
MCH_ 421
Future 06 I Folded glazing
Double skin facade creating a thermal chimney
Sectional model explaining the double skin
Flat pieces of glass fixed at varying angles to create a folded facade
This project shows a folded facade which
metre rates) to be obtained from contrac-
behind another outer wall forming a thermal
came about as the result of a requirement
tors before tender to ensure that the design
flue across part of the elevation.These were
for both a glazed facade and a a double skin
corresponds approximately to the budget.
developed wit the intention of them having a single expression for the glazed facade
facade,which served as thermal chimney, in a different part of the facade.The project
The scheme was developed from a wire-
formi ngthe complete nort h elevation,with
was developed by producing a single digital
frame geometry as a result of different
its wrap around corner contrasting visually
model describing the project to provide
construction options beingconsidered at
with the general areas of facade forming
certainty for the contractor at tender stage,
the outset.These ranged from a mixture
the remainder of the hospital project.The
but allowingthe contractor to bring their
of systems: stick and unitised solutions for
preferred solution was a single expression of
own system without the need for starting
the corner glazing,and point fixed and four
framing members that were differentiated by
all over again.As the model developed,the
edge supported solutions for the thermal
cover caps and smooth silicone sealed joints
design was discussed with potential tender-
flue.The choice of system was informed by
which used a common stick curtain walling
ers to ensure compatibility with their own
the interface between the two glazing types.
system.The sticksystem was preferred over
preferred systems, well before tender.This
The preferred solution was to use two glaz-
a unitised design, which would have required
method also allows budget costs (as square
ing types:a single glazed wall that wrapped
MCH_ 422
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-- -
Sectional models explaining the double skin
MCH_ 423
Future 06 I Folded glazing
Flat pieces of glass fixed at varying angles to create a folded facade
Sectional models through thermal chimney
too many panel t ypes to makeit economi-
that of assembly of the envelope in position
be economicthey need to follow closely the
cal.The building industry is still a long way
on site.
principles of hanging curtain walls from floor
from a complete factory assembled solution
to floor (or supportingthem at their base if
for complex glazed facades on modest scale
W hen the design was almostcomplete, a
this is more efficient). Where facades deviate
projects over the slower site based solution
new digital model was'built' that replicated
from this principle, and becometechnically
with its need for scaffolding.The preference
digitally the work of fabrication and instal-
more ambitious,the supporting structure for
of site-based assembly over unitised methods
lation by a facade contractor.There was no
the facade should still be as straightforward
for small scale complex geometry projects
need to rebuild this as a parametric model
as possible to construct.
makes it important to resolve detailing of
as the inherent complexities in that form of
components and assemblies before tender
modelling can create unnecessary fabrication
Another essential aspect is relative move-
- a complete change of approach required
and installation difficulties for the cladding
ment between parts of the facade, particu-
to suit sit e working methods could drasti-
contractor which, of course, adds an unnec-
larly where facade panels or glazed units are
cally change the design from the visual point
essary extra cost.This new digital model was
supported on different structures, such as
of view.Arguably, factory based methods of
based on a mixture of 2-D and 3-D draw-
where atrium conditions meet adjacent areas
unitised assembly can adapt better to the
ings to ensure the design was resolved as
of structure,and in double facade configura-
demands of facade design, with more tools,
individual components and assemblies that
tions where the inner skin and outer skin are
equipment andtime to assemble facade
corresponded to the required arrangement
constructed in different systems and have
panels or units in more ideal conditions than
in plan and section. For facade systems to
different movement characteristics associated
MCH_ 424
wit h them,as well as movements associated with diffe rent methods of support or points of support between inner and outer skin. Resolution of adjacent facade systems is detailed in a way which makes them economicto fabricate and install, ensuring they are as economic as possible. In addition to a digital model,the folded facades of this project were described a series of flattened elevations in the manner of an 'airfx' type kitof parts.This ensures that the tenderer appreciatesthe level of resolution of the scheme,and that there is little that remains unknown to the contractor, which would otherwise add an inevitable
Sect ional models t hro ugh t hermal chimney
cost to the facades.
MCH_ 425
Future 06 I Folded glazing 3-D view of curved and folded glass comer detail
Details I.Factory assembled untised panel 2. Curved glass (assembled as part of the unitised panel) 3. On site crane 4. Concrete floor slab
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Where this project had extemal, or out-
framing members. In both projects the ends
visual distortion across its surface, which
wardly folding, comers, another project used
of the folded glazed walls abutted masonry
takes away the reflections from the curva-
single curved glass to create series of intemal
walls, which used a rainscreen system in
ture, which is one of its main visual charms.
folds in a facade bounded at its edges by
order to allow the glass to terminate with-
Screen printing on curved glass has been
masonry. Here the panels were made as
out a visible frame at its edges. Although sin-
possible for the pastfew years and is starting
unitised panels rather than a site assembled
gle curved glass is cunrently expensive, more
to find its way into mainstream projects. This
sticksystem, allowing the comer to be
glass companies are beginning to provide
allows the spandrel area at floor level to be
formed as a silicone bonded joint. The aim
curvature with tempering of glass, in particu-
concealed, as well as being a means of pro-
here was to provide a glazed wall which did
lar those based in the Middle East and South
viding solar control to single curved glazed
not have a spandrel panel coveringthe floor
East Asia. Although solar protection coatings
wallswithout using only a coatingwith its
zone, so smoke seals were provided imme-
can be applied to single curved glass, there is
characteristic darker appearance.
diately behindthe transom at floor level,
still difficulty in applying Low-E coatings, but
giving a continuous glass appearance. The
this is gradually evolving. An important issue
glass was silicone bonded on all four sides in
in the use of curved glass isto ensure that
order to give sufficient rigidity to the panel
the material can be made without significant
and avoid the need for additional aluminium
MCH_ 426
....,
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3-D View of curved and folded glass comer detail
3-D View of curved and folded glass comer detail
Future 06 2 Metal solar shading: louvres and mesh
Investigation s into methods of arranging profil ed louvres to provide varying amou nts of shading.
Mesh options
other materials are being explored.
of the graphic being a key factor, in that the
For this project we looked at proposals for three approachesto the design of
printed on meshes, with 'image resolution'
Fabrics
distance from which the image is viewed is
a 'mesh' screen, t hat is, made from woven
Fabrics, which are flexible in one direc-
metal fabrics and variations on this theme.
tion, are woven with rods or flat strips with
achieve visually subtle results with simple
The three categories are fabrics, printed
wire cables in the opposite direction. They
graphics applied in a darker t one than the
an essential consideration. Printed mesh can
mesh and wind animat ed mesh. The first
feature few seams and simple fastening
base mesh, asshown with tree-like pattems
two types are based on woven meshes, as
techniques. Fabrics which are flexible in two
as shown here.
described in chapter 2, while the third type
directions are woven with cables and flex-
is made differently.
ible rods and are the most cloth-like, and
Printed mesh facades are now being
like the first type, they are easy to transport
produced with incorporated media display
An important consideration in the
to sit e and install. Another fabric type, so-
abilities such as LED (light-emitting diode)
choice of material for this application was,
called 'rigid fabrics' are constructed from
displays for large scale applications. These
in addition to the specific material system
a combinat ion of rigid rods and flat strips
are still relatively expensive however and
to be used, the amount of open area for
that are crimped prior to weaving to give a
obviously require more maint enance than
the meshtype, as this affected the amount
characteristic appearance. Rigid meshes are
regular mesh installations. Illuminated mesh-
of light transmittance through the mate-
made as individual panels rather than in long
es, incorporating simple LED lighting systems
rial. A second factor affecting the choice of
lengths and look more like individual panels.
can also be used during hours of darkness.
Printed mesh
Wind animated mesh
material was the weight, as a heavier material requires a bigger supporting structure. Virtually all the meshes considered were low
Printed meshwas also considered, with
This material system uses an anray of
maintenance, durable and recyclable mate-
varioustreatments being available for use
lightweight tiles which are hung from hinges
rials, which is an advantage of this design
on the architectural meshes mentioned
on their top side, allowing them t o move
approach. The meshes are commonly avail-
above, including shot blasting, etching and
in response to air movement around the
able in stainless steel, aluminium and copper,
spray painting. Virtually any graphic can be
outsideof the building. Wi nd blowing across
MCH_ 428
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Various met hod s of using mesh and pro filed louvres to pro vide non- uniform shading
MCH_ 429
Future 06 2 Metal solar shading: louvres and mesh
Shaped mesh panels usedto provide shading
and under the facade causes the tiles to rotate and a rippling effect is achieved along the length of the school in response to the natural environment.
As well ascreating a shading system in a similar wayto fixed mesh, this system brings an animated approach to the facade, allow-
house This altemative to the east facade isto
Design of the metal louvres One of the aspects of the design that
create a glazed double skinned facade, The
was developed in detail was the metal
glazing can be pattemed to provide shading
louvres. Thesewere required to be thin
wit h the void also reducing heat gain into
panels of a natural metal that would weather
the classrooms.
naturally with time. The louvres were large
In this example, the facade system takes
scale; hanging vertically from the top of the
ing components which would usually be
advantage of the double skinned fabric and
building, forward of the extemal wall, to
fixed to respond to the natural environment.
is used in the same way as a green house
provide solar shading. The louvreswere also
for growing plants. These plants will act as
to extend over the roof of the building and
a shading system for the classrooms as well
so neededto support their own weight, as
as an educational resource for the school
well as to resistlive loads, mainly from the
ulated across the length of the facade form-
to grow plants and vegetables within the
wind, Consequently, the louvre forms were
inga contoured surface.
facade.
designed asa frame clad in sheet metal,
Profiled louvres The profile of the louvres can be manip-
Louvres can be deeper andthus provide
Plants in double skinned buildings bring
with the frame made from aluminium box
greater shading where necessary along the
several advantages related to the thermal,
sections, bolted to gether. The shape of the
facade while across other areas the depth
aesthetic, psychological, comfort level, and
truss follows that of the metal panels, which
can be varied.
Double skinned facade greenMCH_ 430
sound attenuations as well ascreating a
were SOOmm x IOOOmm, with the fram-
comfortable indoor climate and saving
ing following the ladder-shaped form of a
energy,
Vierendeel truss. The sheet metal is secured
Using louvres with changing profiles over the walls and roof of a building can provide varying levels of shading and visual interest along a long facade
Future 06 2 Metal solar shading: louvres and mesh
Above. Environment al analysis can be used to infonm whe re different amount s of shading are required
Abo ve. Louvres can be perforated or solid to pro vide different amount s of shading Left W ind animated til es
to the aluminium truss with a series of con-
would not require the connecting rods to
cealed fixingsto give the appearance of a
be fixed back to t he primary structure of the
patchwork of individual panels rather than a
extemal walls, allowing it to be a completely
continuous smooth metal surface.
self-contained structure, exerting dead loads only at roof level. The principle of using con-
The decision to hang the louvres from
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MCH_ 432
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necting rods between louvres was used for
the t op of the building rather than at each
the horizontally-set louvres extending across
floor level was based on the idea of having
the roof, aligning the positio ns of the rods
lightweight metal brackets projecting at each
with joint lines in the glazing below.
floor level to take the lateral (sideways) load of the louvres rather than attempt to support the dead load of the louvres at each
Design of the mesh screens The stainless steel mesh chosen for the
floor level, resulting in a visually lightweight
project was a rigid type, allowing panelsto
supporting structure. Lat eral restraint for t he
be forming without the need for accompa-
facade louvres along the length of the build-
nying structure that would be needed at the
ing were provided by metal rods which were
top and bottom of the wall for a tensioned
connected to the aluminium trusses. A finite
mesh solution. This allowed us to provide
element analysis of the complete structure
a visually lightweight screen that wassup-
demonstrated that the complete structure
ported by an accompanying set of visually
I
lightweight steel brackets projectingfrom
member was set within the 3000m wide
the extemal walls. These brackets matched
frame. Because the metal louvres and steel
the size of the corresponding brackets on
meshwere supported by a connected series
the facade supporting the metal louvres.
of members, which also fixed backto other
The stainless steel mesh was held in an
steel frames supporting glazed walls and
edgeframe on all four sides and was hung
associated maintenance walkways, an essen-
on a mild steel T-section hanging from the
tial aspect of this design was the inter-con-
building at roof level, again using similar
nected nature of the structural design. No
brackets to those supporting the metal lou-
assembly could be designed in isolation; each
vres. Thesewere IOOmm x SOmm sections
formed part of a linked structural system,
hanging vertically at 3000mm centres which
where movement as the result of wind load
were restrained laterally at floor levels. The
affected a whole series of other assemblies
mesh panels spanned 3000mm horizontally
which shared the effects of these move-
between supports, allowing the panels to
ments. This produced effects of movement
appearto float visually in bands across the
in brackets that madethe adjacent glazed
facade. Because stainless steel mesh cannot
walls move slightly, all of which neededto
span this distance and be used asguarding
be accommodated in the design of the glaz-
for maintenance access due to the deflec-
ing system.
tions beingtoo high, an additional vertical
MCH_ 433
Future 06 3 Triangular panels for twisted facades
Studies w here a complex geometry has been rationalised t o allow it be made up of repeated t riangular panels
O ur investigations of curved, twiste d and fo lded facade surfaces have involved
often correspond to an appro ximat ion of a
examining the geomet ry issues associat ed
fo rm t hat can be opt imised mathemat ically
w it h the se forms. T he arrival of digitally
in order t o increase repeatability of facade
controlled too ls in t he construction industry,
panels or com po nents needed. For example,
w it h information supplied t o th e t ool by
curved forms can be opt imised t o create
com puter generat ed drawi ngs, has allow ed
surfaces set out on t he arc of a circle, sphere
a great er diversity of components, w hich
or torus, in o rder t hat a single panel can
potentially reduces the need fo r standardisa-
be used, allowing t he compl ex fo rm of the
t ion of bot h stick and unitised methods in
envelope to be created from a small number
curtain walling. In pract ice, the introduction
of panel t ypes.
of many more claddi ng panel types of differ-
MCH_ 434
would suit digita l fabrication tec hniques
T his proj ect investigat ed different
ent sizes th at w ill be fitted t ogeth er to form
opt ions for facade geomet ries th at can
a com plex arbit rary form is often wasteful of
accommodat e curves, twi sts, folds and
resources and of material. H ow ever, com-
their comb inat ion. Genera lly for curved
plex forms generat ed by archite cts w hich
surfaces, a soluti on w e have researched is
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Investigation into how different pattem s of facade panel can maximise efficiency and create a different aesthetic
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the use of triangular panels. This has several advantages, as the panels are ableto t ake up a circular geometry in the manner of a geodesic dome, fonmed as a sphere of trian-
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gles. Another advantage of this solution is in
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adapting to non-standard conditions such as
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at facade comers where, for example, panels change in size through the height of a build-
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ing as a result of a complex geometry of the building fonm. Two preferred facade systems are being researched for use as triangular panels: a node system similarto that used in large scale stick-built glazed roofs, and a unitised panel system. W e are specifically looking at how they could be usedtogether as a combination of stick and unitised meth-
MCH_ 435
Fut ure 06 3 Triangular pane ls for twisted facades
~:
Studies looking at how a large hexagonal panel might be constructed
ods,with a stick-built node system in areas
complexity arises if a facade has a double
where a standard system cannot be applied
curvature. Unitised cladding panels can be
sented greater challenges when used in
easily, and unitised panels used in main areas.
set in a curve in one direction, as is often
unitised panels that are required to span
This is a departure from the norms of facade
the case with facades curving either in plan
not only from fioor to fioor but alsowhere
construction.
or vertically through their height, but two
greater heights are required to be enclosed,
way curving makes it much more difficult to
such as double skin facades which span two
The triangularpanel solution has pre-
use rectilinearpanels which are repeated
fioors at a time. Where triangularpanels are
isthe addition of curves to the surface and
across the facade. The two methods we
around 2.0 metres x 3.5 metres to suit large
tapers to the edges, allowingthe forms
havedeveloped to dealwith such geometry
(relatively economic glass sizes), glazed units
of extemal envelopes to vary over their
is either folds in areas of fiat facade, which
are set either within a largerpanel assembly
height. Where a taper is used, the facade
gives a visual approximation of an overall
or onto a structurally supportingframe, typi-
has panels which are not simply curving out
curvature, or altematively using triangular
callyin mild steel. Regardless of the method
in one direction over their height but are
panels, as pioneered in the domes of Buck-
of panel support, an essential issue in our
tapering as well, resulting in non-standard
minster Fullerduring the 1960s and devel-
research has been in the geometry of panels.
comer conditions. An additional level of
oped as node-based space frames.
Specific issues of weatherproofing as the
Further complexity in twisted facades
MCH_ 436
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Future 06 3 Triangular panels for twisted facades
A bove. Exploded views of a nodal joint between framing membe rs Below . Diagram showing variat ion in member lengths
MCH_ 438
Above. Sectional view through panel joint Below. Intemal view of panels
-------
result of a need to ensure conrect alignment
W here most node systems are des-
of joints are not discussed here. The fiat
tined for use as stick systems assembled
triangul ar panels designed for economy are
o n sit e, w e have proposed using unitised
required to meet at fold lines. Since folds
panels assembled from node s, wit h only
need to occur o n a plane of infinite thick-
the comer co nditions being sit e assembled .
ness, parts of the panel meeting either for-
Thi s method w ould be used both w here
ward or behind thi s plane will alw ays be out
aluminium framed panels span t wo flo ors
of alignment at the point of intersection . W e
vert ically w it ho ut addit io nal steel suppo rt or
are developing t wo so lut ions for thi s condi-
w here smaller unitised panels are fixed to a
tion: eit her a shadow gap bet ween adjacent
mild steel frame w hich spans t he tw o floo rs
panels or a node connector at th e inte rsec-
in th e same way.
tion of several panels, still using a shadow gap between the edges of adjacent panels.
MCH_ 439
Future 06 4 Twisted panels with flat glass for twisted facades
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Above and left. Investigation into how the geometry of a twisted tower can be broken down into a repeated panel which has a twisted frame but use flatglass.
Left. Twisted roof element Right. Typical structural bay
MCH_ 440
PE!lSPECT ~E VEI;
- - prmari W.;ct;l3 eemerts
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F.DOR PtJt.-J
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In dealing with tw ist in facade struct ures
I,EST ELEVJ.TOt,_t 1000
'un-twisted', in orde r to align the roof wit h
a more rectilinear so lution. The structu re was
t hat suppo rt cladd ing panels, we investigated
the floor level forming an atrium space at
twisted back to its actual positio n, and the
the nature of 'twist' as a visual pheno menon.
th e top of the building. The struct ure was
proce ss of adjustment was don e one more
A roof structure that we designed for a tall
th en adjusted t o suit t his position, as if the
t ime. This process of twisting and un-twisting
building is both curved and twisted to cre-
roof structure were to be co nstructed as
t he roof structure allowed us to understan d
ate a complex shape. The roof cove ring
an 'un-twisted' design. The roof structure
t he 'behaviour' of the structure when under-
itself comprises an opaq ue lightweight deck
was then twisted back to its actual posi-
going tw isting from a rectilinear conce pt to a
protected by an outer memb rane. The sup-
t ion, causing distortion in the structure. The
solutio n that both visually expressed the idea
porting structure was required to be visi ble
revised structu re now looked 'twisted' as
of a tw isted structure as we ll as functioning
and formed a 'lid' to t he twisting facade s
opposed to being a tw isted form that had
as an economic and logical structure in its
of the tow er. The roof was de signed by
a more rectilinear solut ion imposed upon
own right.
esta blishing primary points of support on the
it. This new twisted form was then adjusted
suppo rting core as we ll as po ints on the roof
a second time to make it more suita ble as
plane. The se points were then connected
a structure that wo uld carry the loads of a
facade s is created typically by pulli ng one
wit h struts springing from a set of po ints on
roof dec k Triangular structural members
comer of a notio nal flat panel out of plane.
the central structural core of the building to
were added for this purpose. O nce again
As the panels are set together, the y follow
form a series of notional 'tree' structures.
the structure was un-tw isted to align with
the fl oor plate as a straight line of panels at
The roof structure was then re-rot ated, or
t he floor dec k beneath and adjusted to suit
t he floor level, but their twist creates anot her
The geometry of panels in singletwist
MCH_ 441
Future 06 4 Twisted panels with flat glass for twisted facades
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Systems using bolt fixed glazing
stra ight line in th e floor above at a different
W it hin each facade panel, flat double
angle t o th e floor below. Typically, a facade
glazed units can be inserted into straight
tw ists along it s cent re line (w ith vert ically
aluminium pro files by using diagonally cut
set mull ions in mid facade), wit h panels in a
inserts t hat allow the glass t o fit int o a twist-
single floor being of different shape. How -
ed shape. Th is method allows the aluminium
ever, panels set above each other are of a
extrusions used fo r t he framing to follow
single t ype. A s a result, the design of twisted
regular panel construct ion methods that
facades require cont inuit y vert ically in ord er
incorporate standard methods of pro vid-
to make th e panels economic t o manufac-
ing struct ural th erm al breaks, seals, internal
t ure, as th e use of all different panels on any
drainage and ventilation. The all-important
floor obviously req uires more panel types
comer junctio ns of panels are able to meet
th an a typical unitised facade.
w it h smooth mitred jo ints, an aspect of design that w e have explored through the
1VPICII. SPIIlR CASTIOG WITH IIOllS
use of full size physical mock-ups.
MCH_ 442
Possible mthods of creating a twisted panel using fiat glass
MCH 443
Future 06 4 Twisted panels with flat glass for twisted facades
Above. Section through facade Left. Full size mock-ups of cladding panels Below and right. Furtherstudies of roof element
MCH_ 444
MCH_ 445
Future 06 5 Moving shading panels
o o Unligned : both layers of moving system out of alignement
Facade system using several layers of small louvres to provide controllable shading
- exposedwindow area = approx. 30%
The framing of t his design for solar shad-
wall, which hangs from the edge of a slab.
ing panels is fabricated from extruded alu-
The approach allows t he edge of floor slabs
minium profiles, and these can be designed
to serve as an extemal maintenance deck.
for maximum efficiency of material and
resulting in glazing which is economic in cost.
structural connections. This system also makes connections between t he various
The way t he glazing would be construct-
element s quite straightforward, using well
ed would be unitised (preassembled) rat her
established fixings and techniques. The detail
than sit e-assembled. Site-assembled glazing
is designed t o allow for off-sit e prefabrica-
is slow and expensive, whereas the unit ised
t ion of the shading panel 'cassettes' and
method is cheaper and faster, but needs the
simple installation of these panels on site.
repetitio n of panel size that is characteristic
Insulation and cover panels (a reflection of
of larger scale installat ions.
the ceiling grid pattem) are designed to conceal the framing while still providing for ease
The unitised glazed wall t o t he wall
of maintenance access and visual cont inuity.
behind comprises a system where the framing is set extemally rat her than on the interi-
The extemal glazing behind the shading is conceived as 'storefront' glazing, as the
MCH_ 446
or face. This provides a mullion-free int erior that follows the principle of providing unob-
facade would be built like a storefront. from
structed space in t his project. This allows
floor to ceiling, rather t han like a curtain
the floor and ceiling finishes to extend up
I
Renders showing mov eable shading system from bot h intema l and ext emal views
to the glass, creat ing an elegant space w it hin.
building.
cog w heels that are pow ered by an electri c motor. Each set of moving panels has its own
In order t o maximise daylight tran smission through the facade w hen required, glazing
The extemal shading devices com -
motor linked to operating swit ches set w it hin
exte nds from flo or t o ceiling. Because the
prise prefabricated panels set between the
the office spaces, o perat ed eith er by the user
vert ical structural glazing bars (mullio ns) are
extemal structural column s fixed in fro nt of
or as part of th e BMS (building management
set extemally, the th enmal breaks are set at
the access deck and betw een the extemal
system) . Th e mo ving mechanism for the lou-
th e back of the frame in line w it h t he double
structural column s. Th e system is compri sed
vres is set behind access panels in t he panel
glazed unit s in order to pro vide continuity of
of three layers: one fixed, vert ically set outer
frame in o rder to avo id the effect s of dust,
thenmal insulation.
member, and two mo ving inner members
w hich can affect the smoot h running of the
w hich are set to a variable geom et ry in order
system.
Each of the facade bays w ould be unique.
to cont ro l the amo unt of daylight in the
The shading panels w ill need to connect
building. The fixed vert ical louvre s span from
at different angles w it h differing w idt hs of
floor to floo r and follo w the lines of geom-
louvre elem ent s is con cealed and protected
shading systems. The shading panels fo r
et ry of th e extemal structure of the building.
w it hin t he ext ruded aluminium framing. Shown here is a system based o n an art icu-
the se location s w ill have a bespoke frame to accommodate these variables and allow
The drive mechanism fo r the mo ving
Both fixed and mo ving louvres are made
lat ed chain and spro cket w it h a number of
maximum views out at the comers by mini-
from extruded aluminium sections set into
linked motors. Th e size and specificat ion of
mising the framing. At the comer the fixed
an aluminium suppo rt frame. Th e mo ving
t he motor and atte ndant control systems
vert ical shading sticks w ill meet, to pro vide a
louvres are fixed to a mechanism set int o
would be key t o th e design of the framing.
clean edge th at w ill run up t he length of t he
th e frame, comprising a set of belt s driven by
T he drive system would also ideally need
MCH_ 447
Fut ure 0 6
5 Moving shading panels
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Exploded view showing how a panel incorporating mo veable shading could be constructed
to be as maintenance free as possible, par-
floor heightto a width of around ISOOmm.
ticularly with regards to any potential grit
Each panel is assembled, glazed and sealed
infiltration.
in the factory, then delivered to site in batches of 10or 12at a time by truck. Each
The facade is installed in phases in order
Shading panels are fixed onto brackets secured to the upper surface of the access
unitised panel is lifted either by a monorail
deck. Like the brackets for the unitised
to provide a sealed enclosure to the inte-
set onto the edgeof a floor deck further up
glazing, they are fixed and aligned ready to
rior spaces as quickly as possible, allowing
the building, or is lifted by machine on the
receive the unitised shading panels, ensur-
the extemal shading to be installed after
floor itself if this proves to be difficult. Panels
inga fast installation time that minimises its
floor areas have been sealed, and without
are then lifted into position on the floor
effect on adjacent installation operations.
interfering with installation work inside the
deck and secured at both floor and at soffit
Once shading panels are installed, the col-
building.
levels at the top and bottom of the panels
umn faces are covered wit h thermal insula-
with brackets which are already fixed and
tion and clad wit h precast cladding panels
aligned. Each panel is fixed to the next until
fixed from both the access deck and from
installed by first liftingthem by crane as uni-
the complete floor is enclosed. Floors are
a cradle hungfrom above. W hen this work
tised (factory made) panels onto the floor
typically enclosed from the bottom upward
is complete, the adjacent access deck is
plates, where they are laid out adjacent to
to follow the construction of the primary
covered in thermal insulation after which the
where they will be fixed. Panels are made
structure.
wearing material of the deck is applied as
The extemal glazed walls would be
MCH_ 448
D etailed studies of the mechanical systems t hat might be used to make layers of louvres mo ve
well asslab edge and related soffit cladding.
to the site to be lifted directly to the floors
All this work can proceed independently of
where installation is needed.
ing condition for the mid season with the volumes in place of proposed surrounding
installat ion works within the building. The unitisedglazed panels would be Prefabricated panels for the glazing and
Studies showed a typical solar shad-
fabricated on an assembly line in the classic
buildings. While this study demonstrated that lower floors of the tower would require
the solar shading would be fabricated typi-
mannerto ensure that quality controlled
little shading at this time of year, the system
cally by a fabricator licensed by an intemal
panels are assembled and glazed, ready for
is designed to be variable, and adaptto the
curtain walling company. Several such com-
installation on site. The shading panels would
specific requirements of each area of facade.
panies exist,m aking this method economic
be made in a similar way, wit h extruded
and easier to manage as a supply chain from
aluminium frames being assembled with the
A shading analysis indicated that solar
factory, to temporary storage, to delivery to
louvres in place. The electric motors would
shading was needed on all facades t o reduce
sit e. Since the panels will be installed quickly
have a switch point set within the panel
the effects of solargain at different times of
on site, they would need to be prefabricated
ready for connection to the wiring installed
the year. In the winter season, all facades
in large quantity prior to delivery to sit e. The
on site that would run to the intemal swit ch-
experience low angle sun except the north
size of the site will probably require panels
es. All panels would be t ested for movement
eastelevation, which receives almost no sun.
to be delivered directly from the storage
prior to delivery to site.
facility (which might also be in the factory)
The effectiveness of the louvres in their
MCH_ 449
Fut ure
06
5 Moving shading panels
Sectional and exploded views of louvre shading system
various positions would vary across the span
be required to control the movement of
allow for easy access t o the drive mechanism
of a day, over the year and on the differ-
louvrest o be in t heir most effective align-
for maintenance purposes. The aluminium
ent facades. Generally on the east and west
ment at any given time.
frame can have hinged panels designed into
facing facades the aligned louvreswould provide better shading as the deep fins
The drive system and attached control systems are installed off-sit e duringthe
assembly to allow for this access. To simplify control systems and reduce the potential
are effective against the low sun hitting the
facade panel construction. Connections to
number of motors needed, the drive system
facades at an oblique angle. On the sout h
the moving louvre systems and maintaining
could be geared to vary the range of move-
the unaligned louvres function better as they
a strong fixing for ease of movement will be
ment and speed of the attached louvres.
provide more of a horizontal element which
paramount in the design. The prevention of
helps to block out the higher sun at an angle
sand or grit infiltrating the mechanism must
perpendicular to the facade.
also be a primary design consideration.
The primary access to cleaning the shading panels is from the access deck, which is effectively a continuation of the floor slab
The building management system would
MCH_ 450
The aluminium framing would need to
out of the building. The shading devices pro-
Analysis of the shading effectsof small, moveable louvres
vide a full height balustrade for day-to-day
either from a cradle which is lowered from
safety brackets would be barely visible on
access, but if a panel is partly dismantled for
roof level, or by fonming the shading panels
the facade,
maintenance, then an alternat ive 'balustrade'
as vertically hinged panels which can be
device is needed. W hen shading panels are
opened inwards into the areaoccupied
3S00mm panel would be divided into a pair
In the hinged panel option, each
removed, maintenance staffare secured
by the access deck, from which it can be
of 17S0mm wide hinged leaves. Since each
by their body harness to a safety line set at
accessed.
panel is set approximately ISOOmm in front
In the cradle option, a cradle approxi-
of the glazed facade, panels can be rotated
floor level beneath the curtain wall transom,
mately three metres long by 7S0mm wide
to almost 90 degrees so that they are per-
ensuring that access users cannot be tripped
could serve each bay of shading panels as it
pendicularto the access deck, where they
by the wire itself.
is lowered from the top to the bottom. The
can be freely accessed without the need for
cradle would be temporarily secured in small
a cradle. Maintenance staffwould, of course,
ring brackets set into the facade every two
be secured by the safety line set at floor
fioors vertically, in the classic manner. These
level.
deck level. The safety line is a cable set at
The external face of the shading panels can be accessed by one of two options:
MCH_ 451
Future 06 6 Precast concrete panels for facades of complex geometry
Structural in-situreinforced concrete backingwall with precast concrete cladding
T he work done on thi s facade system focu sed on the nat ure of th e precast concrete panels to suit cur ved planes.These w ere considered as options as follow s:
I.
A single structural wa ll w ith ther-
mal insulation set on the inner face. 2.
A diaphragm wa ll,t hat is to say.
an' inner and o uter reinforc ed concrete w all linked toget her str ucturally across an inner
/~
layer of t her mal insulati on.
3.
A n inner structural wallwith outer
cladding panels and insulation set bet ween t he inner structural w all and the outer cladding.
Given th e geometric, structural and construction parameters. an in-sit u concrete structural wall with precast cladding panels w as considered t o be t he most appropriate solution from the point of view of ease of constru ction.
MCH_ 452
Rendered views of large precastconcrete claddingpanels.
Exploded, sectional views showing thefixing system for large precast concrete cladding panelswith structural reinforced concrete wall behind This option was explored by looking
The methods of panel fabricat ion. includ-
at how panels could be divided into sizes
ingthe type andthickness of insulation to be
equatingto around SOOOkg. allowing them
used. would need to be investigated with all
to be lifted with a regular sit e-based crane.
the likely suppliers of these panels.The focus
Alternatively. panels could be fixed either in
of this investigation would be as local to the
the factory to form part of the inner struc-
site as possible, due to the high costs associ-
tur al wall, or be sit e fixed in the manner of
ated wit h transporting precast panels over
stone cladding panels.
significant distances. Since building systems are in continual development in all industr-
The useof concrete cladding panels in
ialised countries. some companies would be
the third option provided protection for
interested in advancingtheir skills in order
thermal insulation and protection to the
to meet the needs of the project;this is
joints between structural walls behind from
already the approacht aken by leading facade
risk of rainwater penetration.The cladding
contractors.Development of the facade sys-
panels also have the advantage of concealing
tems would need to be undert aken so that
the variability of joint width associated with
the design is able to accommodate a range
loadbearing reinforced concrete walls,
of specific solutions from different precastbased companies.
MCH 453
Future 06 6 Precast concrete panels for facades of complex geometry In addition to the design work of generic systems,the design of all facade systems would need to co-ordinate with building codes with particular regard to wind pressures experienced by the buildings. In addition, CFD studies (computational fluid dynamics studies) would need to be undertaken with computer software to establish any likely areas of high wind pressure in order to understand the effects of wind behaviour on the facades. Precast concrete panel Finished panel stepped areas
Individual precast panels The panels would be castoff-site using curved latex mouldsto create the form for each panel.This formwork could be reused to create repeated panels across the complete facades. Each individual panel has a thickness of around ISOmm and would weigh in the region of five tonnes, but which could be broken down into smaller sections to ease construction if needed. In order to support these large panels metal hangers would be cast into the concrete.These would aid both in liftingthe panels into place on the facade as well as fixing backto the structure behind. Spacer bolts would also be cast in and will tie the panels backto the structural wall behind particularly aiding in supporting the panels at inclined areas on the facade.
Rubber mould Base formwork
Glazed openings within precast panels The glazed openings comprise double glazed unitsthat would be set on the inside face of the panels to maximise the depth of the reveals to the openings, as is common in masonry and concrete-based construction.
Panel types An essential issue in the design of the panel was to ensure that they could be of different types without adding significantly Rendered views showing process of precast concrete panel
to cost. It was found that panels can be of different length for straight and curved panels of the same radius by using moulds where edge restraint s could slide, held in
MCH_ 454
Ribbon mould sections
\
Window moulds
" Base fo
wo
Additional decorative profiles
--------)
Rendered views show ing process of precast concrete panel
MCH_ 455
Future 06 6 Precast concrete panels for facades of complex geometry
I I
I
)
Explod ed views of precast conc rete wall panels w ith thermal insulation on the inside face
place by fixed restraints o n the o pposite two
was found to be much more eco nom ic to
forcement fo r t he complet e pane l in place ,
sides.This is usually possible only with steel
create surface textures on t he face of t he
then tu rning the cast face over while curing
mo ulds, which are used many t imes in t he
concrete t han to create a relief of different
in order to cast t he ot her face t o form a
manufacture of precast conc rete panels, but
depths of concrete ,t hough the addition
str ucturally int egral corn er panel.
are usually fabricat ed by specialist com panies
of smaller cast concrete elements to th e
rather than by precast comp anies, who make
finis hed surface of the panel can be a more
Anot her essent ial aspect of t he design of
mo ulds typically for straightforward panel
cost effective method of creating a rich sur-
precast concrete panels is how they are lift-
shapes on ly.
face pattern that can cast shadows as well as
ed into place.W here the y are set onto or in
provide te xture .
front of con crete floor slabs,th e fixing meth -
Sculpted relief in the surface of the panel was found to be difficult to undertake, and
od is relat ivelystraightfo rward, as panels can It was found that corner panels for the
be set o nto brackets fixed to the floor slab,
was therefore ex pensive due to the amo unt
curved types can be cast wit h one face up
either on the vert ical edge , or on the surface
of mater ial needed to create the ext ra
to around 200mm long when formed as
of the floo r slab itself Where the panels are
material, typically wit h moulded rubber but
a single pane l.Corner panels wit h longe r
used as a facing to backing wall, eit her in
also wit h CNC-cut polymer board of a type
lengths on each face are made in two pieces,
reinfo rced concrete o r in a different material,
similar to that used for the rmal insulation. It
fi rst by casting o ne side wit h the stee l rein-
bracket s can be more difficult t o reac h when
MCH_ 456
Sectional views showing precast concrete cladding panels with structural reinforced concrete backing wall faced with thermal insulation
Exploded view s of precast concrete w all panels w it h thermal insulation on the inside face
they are fixed in place. Brackets must be fixed in a way that is easy to reach w hen the panel is required to be fixed from the front. Associated with the fixings is the method of lifting panels into place so that the lifting hooks fixed to the panels can be removed w hen secured. Panels w hich are cur ved vertically are required to be manoeu vred from both top and bottom in most instances in order to reach their position on the w all.T he overall shape of the panel and positioning of the lifting hooks on the back of the panel can be adjusted so that the panel can be lifted into place w it hout the need to rotate the panel horizontally.
MCH_ 457
Future 06 7 Glazing systems with integral solar shading
Rendered views a cladding system wit h integated louvres
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I
Enviro nmental considerations Proposals for this project were based around the idea of providinga new facade for an existing building that would allow the existing natural ventilation of the buildingto be maintained and to be improved in terms of performance. In addition. t he facade would also provide enhanced solar shading which is provided only by intemal blinds in the existing facade. The options were designed to achievethis within a single facade rather than a double facade in order to be both economic and to allow users a direct link to the outside air which rises only a few floors above its neighbours.
MCH_ 458
The louvres are an integral part of each glazing panel and provide both shading and protect against the wind so that windows can be opened up the ful height of the building
An obvious disadvantage with opening lights in buildings above two or three storeys is the effect of wind gusts, which make high level opening windows difficult to use. Whil e trickle vents can provide minimum levels of air replacement. as used in dwellings, they cannot replace the control and comfort associated wit h opening windows. The design options that were developed used baffles which create local eddies and zones of turbulence that draw wind away from areas immediately adjacent to opening windows. These baffles also provide solar prot ection but their different requirements are balanced in the design.
MCH_ 459
Future 06 7 Glazing systems with integral solar shading
Computer generated views of a proposal where louvres buck and twist to provide different levels of shading across the building
A 3-D digital model of the existing build-
Levels of daylight in the existing building
Infonmation for insulation, daylighting,
ing and its surroundings was created in order
were studied with a digital model in order
average operating temperature, shadow
to understand the response of the building's
to understand the effect of introducing solar
and CFD (wind) analysis is gathered into
facade to insolation, that is to say its solar
shading on intemal daylight levels. It was
a spreadsheet in order to understand the
gain, aswell as the solar shadihg provided
established that although the existing build-
effect of changes in one or several of the
by the adjacent buildings. It was found that
ing enjoyed high levels of natural daylighting,
environmental design parameters. The
the existing building experiences significant
there is an attendant solargain which reduc-
design matrix allows different design options
amounts of insolation on all four facades.
esthe benefits of high intemal daylight levels.
for the new facades to be compared both in
Consequently, a new extemal envelope
This infonmation provided sufficient data for
tenms of their relative perfonmance aswell
would need to deal with the effects of solar
a thenmal comfort diagram which illustrated
as the effect of making changes of geometry
the need for greater levels of thenmal insula-
within the facade options themselves.
gain on all four sides of the building.
tion in the extemal walls.
MCH_ 460
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, I
Facade options One solution consists of cast glass channels which are used to create both translucent and opaque areas of wall around opening windows. This concept is essentially one of replacing the existing windows and
3D
Above right. printed model of facade Abo ve and below . Computer generated views of t wisting louvres
substituting the facade panels above and below windows with a facade build-upthat provides greater levels of thennnal insulation as well as a greater mix of translucency than is achieved by the current facade. This would allow the building to maintain its high levels of natural daylighting of intemal spaces while increasing the level of thennnal comfort. This option would also reduce heat loss to the outside as well as controlling solar gain during summer months. From a visual point of view, the timber framed windows contrast with the three dimensional effect of the glass planks with their glass flanges being visible from the outside. A timber framed backing wall to the glass planks fonnns a continuity with the timber framed openingwindows. W indows would typically be sliding, allow-
MCH_ 461
Futu re 06 7 Glazing systems w ith int egral solar shading
Close-up view s of t wisting louvres
ingthem to be wider than hinged windows,
rather than from primarily visual considera-
following the environmental 'facade map'
with their vertical edges providing control-
t ions. Louvre blades are set horizontally to
for this option. This option is based on a
lable amounts of ventilation. The use of tim-
suit protection from a primarily high angle
framing system of variable depth that can
ber allows separate vents to be incorporated
sun, while vertically arranged blades suit
respondto varying amounts of solar gain as
easily and economically into the windows,
protection for low angle sun. Louvre panels
well ascontrolling daylight levels, which in
avoiding the need to open windows in win-
are set forward of sliding windows set into a
tum affectsthe operating temperature of
ter, and using the vents instead to introduce
curtain walling systemthat uses metal faced
intemal spaces. Blending t hese requirements
fresh air from outside. Castglass planks can
panels above and below windows.The
with reducing wind pressure on openable
also be set into framed windows in order to
modular nature of the facade construction
windows is achieved by using the framing
provide greater protection from the effects
lends itselfto prefabricated construction,
as aerofoilsto move points of high pressure
of wind when windows are opened. Planks
wit h unitised panels having the louvres fixed
and any associated turbulence to other parts
are positioned so as t o avoid difficulties in
to the glazed panels in the factory.
of the facade.
cleaning the facades from the outside. The approach taken in two further
The second of thesetwo options has
options is of providing a framing to the
a continuous folding strip of shading which
panel types that provide different transpar-
glazed walls which serves as both solar shad-
either forms an integral part of the window
ency and orientation. Panels are set out from
ing and as a wind baffle to opening windows.
wall or altematively is set slight ly forward
an environmental 'facade map' of overlaid
In one of these options the inclined fram-
of it. The strip projects outwards from
solar shading and wind baffle requirements,
ing members formingthe vertical lines are
the facade where solar shading from high
Another option uses a set of louvre
which provides an arrangement of panels
orientated to optimise and balance require-
angle sun is required, and flattens against
derived from these specific requirements
ments of solar shading and wind protection,
the facade where either more daylight is
MCH_ 462
required, less wind protection is needed, or a combination of these factors. This option directs air up and down the facade following
Above. Sectional view through facade
preliminary CFD (wind) analysis studies. The angle of the curving solari wind baffles varies from vertical, to suit low angle sun, to horizontal, to suit high angle sun, as used in the louvered option.
The final option is primarily a structural solution, allowing the facade to be supported from the ground rather than from slab edges as per conventional curtain walling. The facade structure forms a set of int erlinking arches that also provide solarshading. Additional members have been added at upper levels to provide shading in more exposed parts of the building.
MCH_ 463
Future 06 8 Stick glazing for double facades
Views of clamp fixed glazi ng facade with PV covered shading fins
The design options for the glazed envelope of this project are based on cladding
smaller pods which can use projecting areas of framing to provide solar shading. The grid
a form set out on two intersecting surfaces
is set up by mapping points on the facade
that together form a curved structure. The
that map the levels of solarradiation experi-
cladding was designed to be supported on
enced over a 12month cycle. These points
a structural grid of approximately 10 metres
are joined in a grid, then the linesjoiningthe
x 10metres, which could be formed in dif-
points are intersected by lines which meet
ferent ways: asa grid shell, as a set of tied
t o form a set of lineswhich are as far as
arches, or as a combination of arches and
possible from each of the points. These lines
grid shell.
are in tum intersected where they meet to form another irregular grid with points set
The first design uses a Voronoi grid gen-
MCH_ 464
at the centre of each new panel formed.
erated from a 'point cloud' of solar gain envi-
The Voronoi grid of panels forms the shape
ronmental data. Visually this can be seen as a
of the facade cladding panels, which are set
parallel to the wings of an insect, where ele-
onto a grid formed from mild steel tubes
ments of the primary structure of the wing
which are welded together. These frames
are linked by secondarymembers that form
are fixed backto the primary structure set at
an inregular web-like grid. Essentially, areasof
10metre x 10metre centres. The two sides
the facade experiencing high overall amounts
of glazed structures reveal very different
of solar radiation over a year are made into
shading pattems on the facades, providing a
Rendered images showing curved steel structure which supports glazed panels
MCH_ 465
Future 06 8 Stick glazing for double facades
Imagesor a system wrucn uses a racaae
structure
oasea on a voronoi panem to support Irregular snapec
giazeo
panels
visually rich mixof grids when seen through
smooth curve without the need for curva-
of one metre. The curved elements are tied
the depth of the building. as experienced
ture across the surface of the glass. Glass
together with stainless steel cables that cre-
at night. Whe re the Voronoi grid of facade
panels are secured with clamped fixings.
ate a facetted facade that has a curved sup-
panels covers the lines of primary structure,
with silicone joints between the panels. This
porting structure. The cables are tensioned
the glass curves over it in order to reduce
ensures t hat rainwater flows across the face
against the primary structure set on an
the distance of the glass from the primary
of the facade unrestricted by glazing bars
irregular 10 met re x 10 metre grid. Glazing
structure, which makes it more efficient. The
that would project forward of the glass,and
is supported on point fixed glazing to allow
curving of the glass creates a 'wave' effect
impede the flow of water across such a large
the four glazed panels to be seated differ-
across the surface of the facade. The glass
surface area.
ently where they meet at the comers. Since the panelswill meet at different angles and
has a double curvature along one side only, while the glass above and below the area
The second design uses curved tubular
on slightly diffe rent planes where they meet,
of the curve that fonms the wave is flat. The
members anranged in a way that reduces
large scale nature of the glazed envelope
spans of the glass to less than two metres
set independently of its neighbouring fixings.
ensures that flat panels will provide a visually
in length. while maintaining a constant width
This method of fixing glazing is in contrast to
MCH_ 466
the bolt fixings allow each glass panel to be
Above. Detail of the supporting structure including a curved lapped panel
Left. Overview of voronoi pattem Below. Details supporting structure
MCH 467
Fut ure 06 8 Stick glazi ng fo r do uble facades
Images of a solution where the primary structure is set out on a roughly 10m x 10m grid but secondary supports w hich hold the glass patt em s take up a more organic shape and allow glass panels I m w ide
patch fixings used in clamped glazing, where
vide a visually dynamic relationship between
The fourth design is based on the use of
the alignment of glass is neededto accom-
the tiled panels. The glazing is fixed backto a
parallelogram-shaped glazed panels which
modate this simplerfixingtype.
set of mild steel tubes which span between
have triangular-shaped perforated metal
primary structural members, using point fix-
panels set above them to provide solar
ings set in the centre of each panel. The gap
shading. The shape of the shading panels
glazed panels which are lapped over one
between adjacent panels is sealed with a
varies according to its location and the
another to accommodate both movement in
metal faced insulated panel which is held in
amount of solarcontrol needed in relation
the supporting structure as well as deal with
compression by the fixing bolts for the glaz-
to the levels of daylight required within the
dimensional variat ion in the structural grid
ing. and secured with mechanical fixings to
building. The mixed requirements of solar
across the structure. This approach allows
ensure its correct positioning. This approach
shading and daylighting are determined by
panels to lap over one another by varying
allows glazed panels to move independently
both the geometry of the shading panels and
amounts to take up differences in module
to one another as a result of structural and
the percentage of perforation of the metal
size rather than use panels of many different
thermal movement.
sheet.
The third design comprises a set of
sizes. Double glazed units are curved in one direction and cut along curved lines to pro-
MCH_ 468
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....
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...
....
,
.
..
,.
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Images showing clamped glazing fixings
MCH 469
Future 06 9 Shingled glazing for facades of comp lex geometry
/ /
/
Lapped shaped glazing panels supported off a 10mx IOm primary structuregrid
climate conditions. The 'mat erial system' is of the project that could be communicated
not only the physical properties and meth-
seen in new projects of complex geometry
to cladding contractors, avoidingthem hav-
ods of working with a particularmaterial but
is in the useof digital fabrication techniques
ingto become involved in the early problem
also the rules of useof a particularfacade
for physical modelling and rapid prototyp-
solving issues raised by havingtwo dimen-
system in a given material. How a facade
ing, allowing an investigation of issues of
sional drawings supplied by designers at
system is drained, ventilat ed, and deals wit h
climate with environmental design software
the tender stage. We think that the useof
variations in temperature as a result of cli-
using different design options. This project
three dimensional modelling with parametric
mate conditions, are fundamental aspects of
involved the development of a methodology
modelling tools, which can be linked directly
facade design that digital fabrication allows
that allowed us to usea common method
to manufacturing, will have a big influence
a greater appreciation of duringthe design
The biggest developmentthat can be
of working from the start of a project to its
on facade design in the comingyears. We
stage before tender. This digital fabrication
completion. For this reason we used compu-
considerthat the use of digital fabrication
may be canried out with facade specialists or
ter software programmes that ranged from
should not be used simply as a method of
cladding contractors before tender as well as
environmental design, to three dimensional
making the manufacturing process easier,
when the project moves into the first phase
CAD , surface modelling, structural analysis
but as a tool that allows designers to better
of working drawings, before the contractor
and parametric geometry. This combination
understand the 'material system' used for a
starts his fabrication drawings.
of digital tools allowed us to build a model
project and how it can respondto specific
MCH_ 470
Overview of apped shaped glazing panel system
MCH_ 47 1
Future 06 9 Shingled glazing for facades of complex geometry
Detailed rendered view of lapped panels
In terms of materials, the use of timber as a primary material for engineered facade
the lighter insulated sandwich panels that
of facades as non-loadbearing cladding. The
systems has increased significantly over the
combine the advantages of prefabrication
use of 'cladding', asopposed to loadbearing
pastfive years. This is in part due to its pop-
with the equal advantages of site fabrication
walls, has come to dominate architectural
ularity in housing, where the general public
that suits non-standard facade conditions.
design, partly due to the fact that build-
are beginning to see new homes asan engineered 'kit of parts'that can be adapted to
ing envelopes are required to provide high Another application of digital fabrica-
levels of thermal insulation, which can be
suit context and climate. The techniques of
tion techniques is in concrete formwork
provided by wrappingthe building in an insu-
using laminated timber panels and sections
made from a combination of polymer foam
latinglayer over the face of anyvisible struc-
are now infiuencing largerscale structures. In
materials andtimber. This new generation
ture. The introduction of thermal insulation
common with some other materials, timber
of formwork is being developed to pro-
within structural materials, rather than over
lends itselfto digital fabrication, delivered
vide greater sculptural effects in reinforced
them, has allowed the possibility of structure
to site in fiat packform as prefabricated
concrete structures and facades both in
being used both as a structural and visible
panels. The advantage of timber to date has
reinforced concrete andthe emerging useof
part of the facade design where its benefits
been in its high strength to weight ratio, but
fibre reinforced concrete. Consequently, we
of thermal mass can once again be used.
the solidtimber panels are of course much
are seeing in our work a gradual interest in
Another areaof research we are
heavier. We are researching a combination
loadbearing facades in reinforced concrete,
engaged in is in the development of 'mini-
of these heavierlaminated elements with
a move awayfrom the contemporary use
Above. Section showi ng sealed connection between panels
Future 06 9 Shingled glazing for facades of complex geometry
Detailed rendered view of lapped panels
testing' for water tightness of small scale
of testing at the level of small scale assembly
aimed at allowing the design of facades to
facade samples. This research aims to allow
were available. This will allow a 'pattem of
incorporate issues of thermal insulation and
usto perform rudimentarywat ertightness
behaviour' to be established for variations to
of a response to climate while maintaining
tests on prototypes quickly and cheaply,
a facade system rather than attempt to opti-
high levels of technical performance. The
permitting more teststo be done (with
mise a design completely before a single full
increased use of natural ventilation, rather
approximate results) and allowing changes
test is carried out, where only a 'pass' or 'fail'
than mechanical vent ilation, is driving facades
to the design to be explored through a
can be registered. Consequently, the design
to draw in air in controlled ways around
series oftested mock-ups that reveal the
of the cladding is not investigated under test
buildings. Increasedthermal insulation is
behaviour of facade systems when their
conditions but rather the quality of fabrica-
reducing dependency on fossil fuels, as much
design is changed. Current test rigs for
tion and assembly that ensures the chosen
lower amounts of heating required in build-
facades are large, specialised and expensive
design performs successfully. The 'mini-test'
ings can be generated by altemative means.
to operate. This approach tends to favour
would be a design tool as much as a verifica-
Techniques of mastering the increased
as few detailing conditions as possible being
tion to ol. Since a rapid prototyped mock-up
geometric complexity of facades, informed
created in the facade design in order to sim-
can be made quickly, follow-up tests could
by the generation of air movement, can be
plify a taskthat is difficult to explore three
be arranged soon after by modifying the
translated to economic production through
dimensionally, either technically or visually.
design, 're-print ing' the model andtesting
the use of rapid prototyping and digital fab-
The simplification of the design results in
again accordingly.
rication.
a more conservative and less exploratory approach than would be taken if a method
MCH_ 474
These future developments are all
Physical mode]of facade using pieceslasercut with data exported directly from the computer model
MCH_ 475
Future 06 10 Variable concrete panels for so lar shading
Rendered view of a structural facade w hich also pro vides shading.
Biomimetics and do uble skin facades in cool climates
'structure' and 'skin' from which its complete
tion as well as to allow larger buildings to
body is formed. There is no separate 'head'
be naturally venti lated rather than relying on mechanical ventilation systems.
A recent trend in contemporary archi-
or 'feet'; rather the creature has a stnucture
t ecture, responsible for twisted and folded
adapted locally to suit particular body func-
geometric forms, is that of biomimetics.
tions.
Whe re most 'modem' architecture can be
This observation from nature has been
The use of double skin facades has led facades beingshaped t o suit particular requirements such as encouraging air move-
regarded asa collage of separate volumes
used in the design of buildings which display
ment in a space that uses natural ventila-
and objects linked as a formal composition,
a cont inuity of form, such as where a single
tion. Another reason for visually sculpting a facade is in order t o optimise t he form to
biomimetic-inspired architecture looks to
expression is used for both wall and roof in
the natural world for inspiratio n, where living
a visually complex solution. In such designs,
reduce the amount of energy that wo uld be
creatures are made from a single material
the outer wall is often separated from the
required to temper the space, typically by
'system' (like a mass produced component)
inner wall, which responds t o specific func-
making t he volume between inner and outer
that makes local adjustments to its form
tional requirements within the building. The
skins wider at the floor level then narrower
where changes are needed, rather than cre-
resulting double skin facade typically uses
at the to p. Wh ere adjacent spaces are linked
ate a different form. An example in nature is
the zone between the inner and outer walls
vertically, such as in superimposed atriums,
the earth worm, which has a single system of
to provide higher levels of thermal insula-
the overall form of the building envelope
MCH_ 476
Some of the o~enings are filledwith a mesh which provides increased amounts of shading. This treatment would depend on the function of the areas behind the facade.
JII I
B
1=
Future 06 10 Variable concrete panels for so lar shad ing
O pt ion for a facade using organic forms in reinforced concrete to create a structural facade aro und a curved building. A bove. Views of a section of facade Left. O verview of system over an ext ended area of the facade
might be twisted, curved or folded. For
the summer conditions experienced in tem-
of an outer glazed wall, an overall form of
the design of facades, the definit ion of this
perate climates. For most of the year, glazed
complex geometry can result from shading
geometry and the form of facade construc-
double skin facades are impractical due to
that is set specifically to respond to the path
tion used become primary issues for the
a high build-up of heat that would occur
of the sun. Wh ile external shading devices
facade designer. This project for an external
behind a sealed outer glazed skin that would
often present fewer technical challenges than
shading system sets out a proposal where
not be mechanically ventilated. Consequent-
complex geometries for sealed facade panels,
variation in the shading is provided within a
ly, where two glazed skins are provided,
the visual aspect presents issues for architects
variable geometry of the external shading of
the outer skin serves only as solar shading
and engineers. Again, a biomimetics-inspired
a building in a hot, humid climate.
set forward of a sealed glazed wall. W here
architectural approach allows the facade to
external shading devices have been intro-
be viewed as an organism made up of a small
duced in this region, significant reductions
number of components which have local var-
have been made in the cooling requirement
iations of that system as a response to specif-
plex geometries in sealed or ventilated dou-
for mechanical ventilatio n within the buildings
ic climate-based needs. Fixed shading devices
ble facades is finding a parallel in facadesfor
when compared to the classic solutio n of a
are designed typically t o be opt imised t o suit
hot climates. In such conditions the wint er
curtain wall with reflective glass.
a range of conditio ns thro ughout the year. In
External shading in hot climates The approach taken in exploring com-
conditions correspond, to some extent, to
MCH_ 478
W here shading devices are used forward
our work, this is done by making studies of
-:
Structural facade system using a regular diagonal grid in reinforced concrete
insolation and daylight levels throughout the
beneficial in conditions where glazed facades
year and setting shading devices at different
were exposed to the effects of the sunfor
fixed angles to follow the path of the sun
only part of the day. Generally, mechanically
in a position that would provide as much
operated shading was found to have little
protection as possible throughout the year.
benefit in highly exposed conditions where
In practice this has meant that the shading is
the systemwould consume more energy
least efficientfor low angle wint er sun in the
to operate than the conresponding saving
early aftemoon, but this situation is assisted
in mechanical vent ilat ion from the reduced
by int emal blinds which, although not pro-
solargain. However, on facades which expe-
viding any reduction in heat gain, reducethe
rience direct solar radiation for only part
effects of glare duringthis period.
of the day, we found that a mechanically
W e have also explored the idea of
operated shading system can be beneficial
using motorised shading in order to better
in reducing the energy load for mechanical
exclude solar radiation at different times
ventilation within a building.
of year in facade projects located in hot climates. This approach was found to be
MCH 479
Fut ure 06 10 Variable concrete pane ls for so lar shad ing
Above and below. Perforated louvres which are moveableallow the shading to track the sun offering maximum protection at different times of day. The horizontal setting shown below would be effective against a high sun whilst the sit uation above when the sun is lower.
MCH_ 480
A bove and below. Shading screens w hich can be moved to pro vide more or less shading depending on t he function or user inside a space.
MCH_ 481
Future 06 I I Structural facades of complex geometry
A grided pattem of members provides both shading and structural support to the facade
This project was a design to integrate
most of the teaching day, creating a striking,
It was decided that timber would suit
an extemally-set loadbearing structure with
fluid form over the entirety of the extemal
this principle, creating a material system wit h
a system of solar shading. The structure is
envelope.
the flexibility of fabrication and ease of instal-
based on a design of interlocking arches, forming a structure similar in construction to
lation to matchthe required physical form. The density and spacing of the structural
Metal was considered as altemative, but the
a gridshell used for roofs. In environmental
members was adjusted in different areas of
ease of jointing in timber, combined with its
terms,the design worlks like a set of extemal
the facadeto provide varying levels of day-
economy, made it a preferable solution.
louvres set in front of a wall wit h significant
light penetration. The depth of the individual
areas of glazed wall. In this case, the facade
members was also varied over the structure
behind is approximately 50% glazed in order
In terms of solar shading, the effective-
to accommodate different lighting require-
ness of the 'louvre' pattem across this west
to provide adequate daylight into teach-
ments. In addit ion, the structure provides a
facing facade varies depending on the time
ing areas of an academic environment. The
frame which could support panelised meshes
of year. In the summer months the louvres
extemal structure serves as a complete
to act as devices for localized solar shading
are not very effective in the late aftemoon.
shading element that allows light to enter
and control of daylight.
This is particularly true in the areas of the
but blocks the sun in the mid season for
MCH_ 482
facade where the louvres are more widely
The structure becom es more dense towards the top of the building which provides more shading and visual variatio n across the facade
MCH 483
Future 06 I I Structural facades of complex geometry ,, ,, ,
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A solution w hich uses a grid of curved members as bot h shading and structure
spaced. They are much more effective dur-
The idea of the structural facade was
ing winter although there are still areas with
continued asa non-loadbearing screen of
is lower, the roof is virtually fully shaded
high levels of direct sunlight in lower parts
louvres across the roof of the building, pro-
with almost no direct sunlight falli ng on it.
of the building, but the large sports spaces
viding limited solarshading t o large areas
In the summer, however, the roof is almost
at this level made the need for shading less
of glazed roof immediately beneath the
constantly exposed t o the much higher sun.
acut e, providing a more direct link with the
shading. The shading effect of the louvres
This exposure was reduced by making the
experience of the adjacent extemal sports
set above the roof provides an even greater
louvres higher which increased their effec-
areas.
variation in its overall performance over
tive shading depth combined with increas-
a year than the adjacent west facing wall.
ing the frequency of the louvres locally to
MCH_ 484
During the winter months, when the sun
Sectional view\; th rough t he structural facade
shade areas beneath that required it. Both
rounding buildings. O nly in the moming on
on the supporting structure aswell as the
these solutions resulted in a decrease of
the east facade and afternoon on the west
adjacent external walls, which was addressed
the amount of daylight entering the atri um
facade during t he winter months does sig-
in a number of ways. A smooth concrete
spaces below, although the reduction would
nificant shading occur and this shading does
finish can be achieved as a 'honed finish' wit h
probably be less if the louvres were t aller
not cover more than a single comer of the
precast concrete panels, achieving a finish
rather than by increasing their frequency.
facade at any time.
similar to that of the text ure of stone. The use of precastconcrete t echniques allows a
In the case of this project. there is very little shading on the building from the sur-
The design was explored further by considering the expression of 'concrete'
wide range of textures and surface modelling to be applied as well asa high degree
MCH_ 485
Future 06 I I Structural facades of complex geometry
Detailed view showing glass panels fitting between structural! shading members
MCH_ 486
Structural facace solut ion where a regular column grid is skewed to provide varying amounts of shading where needed
of dimensional control which is useful when
block or metal framed insulated panels can
coordinating panel joints wit h fixing for the
be used. Terracotta is economic and over-
louvres set between the main structural
extemal shading devices.
comes the difficulty of using brickwork on
members, an additional metal mesh shading
large areas of wall, where dimensional coor-
system could be used to increasethe effi-
Large scale precast concrete compo-
As an altemative to the use of additional
dination with the more precise components
ciency of the facade, reducing light penetra-
nentsfor extemal walls typically span from
and assemblies of the shading system can
tion into the large spaces behind. On areas
floor to floor and can be insulated within
be difficultto achieve. Shingled terracotta
of the facade which require more shading
their depth, allowing surface finishes to be
tiles provide greater surface modelling and
the grid can be adjusted to become more
applied directly to the intemal face of the
texture than flat t erracotta panels, which
dense. The pattem of the facade canthen
panel. Large areas of concrete can be col-
moves the expression of the facade away
respondto light requirements of the intemal
oured but variat ion in colour as a result of
from sharp joint lines to a surface that read-
functions of the building or an environmen-
the difficulty of maintaining a consistent col-
ily accepts windows which are not set out
tal analysis of the facade. This approach to
our can be addressed by use of a range of
on a precise repetitive grid. However, the
the shading could be part of the loadbear-
hues from panel to panel to create a 'patch-
idea of combining an extemally-set precast
ingtree-like structure which supports and
work' effect W all panels can be loadbearing
concrete structure with precastwall panels
becomes part of this grid. The structure can
or be used as cladding.
will be developed in another project, with a
change in depth in a tree-like mannerto
language that would allow the extemally-set
provide more shading on the t op stories of
structure to appear to be pulling out of the
t he school. As in t he previous proposal the
precastwalls behind.
grid runs across the roof providing shading
Precast concrete wall panels can be clad in other materials such as terracotta, but other backing walls such as concret e
to the atrium in a series of angled louvres.
MCH_ 487
Future 06 12 Facade with integrated fumitu re
Facade solution where a repeated cladding panel forms an enclosure, provides shading. houses heating and electrical fittings and acts as cupboards and shelves
The idea of a extemal envelope which
joints, as well as partially interlocking with
The panel itselfis formed from alumin-
isgenerated from the fumiture of a building
the panel below, and are usually set forward
ium extnusions that interlock with nubber-
and becomes as much a part of the fumiture
of the edge of the tloor slab, away from any
based seals at both tloor level and ceiling
as a weat her barrier was explored in the
stnuctural columns. The aim here was to set
level. This ensures that weather seals are to
Fumiture House by Shigenu Ban, asshown in
out columns at closercentres than would
the standards expected in regular curtain
the first section of this chapter. This project,
t ypically be the case and allow panels to be
walling. The frame is made either 300mm
which did not need tloor to ceiling glazing,
supported at tloor level. This allowed the
deep or 600mm deep to suit the panel type,
but did require deskand storage near the
perception of the panel from the inside to
either for useas shelving, or as deeper desk
windows, was an opportunity to integrate
be of an individual window bay rather than a
space and storage space. The 600mm deep
window and fumiture in a complete extemal
separat e wall.
desk-based panel has a work surface set at 800mm above the finished tloor level, with
wall systemfor a ten storey university building.
Each panel, approximately three metres
room for storage above the window height.
wide and of storey height, was sealed against
The window itselfcan be either full height
the stnuctural slab at tloor level, with a skirt
or half height, but only the lower portion of
fit between stnuctural columns set at
tlashing from the panel set immediately
the window opens, as the panel above is too
approximat ely 3000mm centres, and were
above providing a weather seal. The sides of
high to reach, and the ethos of the solution
set between columns rather than be forward
the panel were sealed against the face of the
is concemed with a straightforward solut ion
Panels were based on unitsthat would
of them as would t ypically be the case in
column, with thermal insulation set around
that has no mechanical devices to control
a unitised panel system. Typically, unitised
the outer face of the column to provide
the opening and closing of the window.
panels are slotted together on their vertical
thermal insulation.
Instead, the panel has electrical sockets and
MCH_ 488
Left: Section through cladding unit.
wiring built into it for desk lighting and desk top equipment such as power for a laptop computer.
The 300mm deep panel has shelving built either below the w indow, or both above and below the opening light. Although the panel w as approximately two and a half times the w eight of a regular unitised panel, it could still be lifted into position in the building by a hoist set at roof level. Speed of construction dictated that the fumiture w ould be mostl y fitted in the factory rather than on site, but sliding fioors w ould still be fitted after the panels w ere lifted into place.
This approach to the construction of the panel allowed a mixture of materials in a single panel t ype. Windows w ould be timber faced intemall y, but be fonrned in alu-
MCH_ 489
Future 06 /2 Facade wit h int egrat ed furniture
I
Variations of the multi-functional cladding panel including meshscreens or timber louvres extemally
minium extrusions externally. The use of all
pro vide a weather seal and durable cover-
timber w indow s within an aluminium carrier
ing to the reinforced concrete slab. Thermal
frame was considered carefully, but could
insulation is set below the metal panel to
not achieve the weather tightness required
avoid a thermal bridge around the edge of
at high level. Windows w ere sliding, though
the concrete slab.
parallel push-out t ype windows were considered, and might form part of the development of this furniture w all system.
Another development of the panel was to pro vide a sliding so lar shading screen on the outer face of the panel which also
A further development of the idea was
MCH_ 490
served as a w ind break for the opening win-
to attach a gantry on the outside of the
dow. Rather than being a translucent screen
panel for w indow cleaning access. In this
pro viding 30% to 50% shading, the panel
proposal, the edge of the floor slab was pro-
was largely opaque in order to serve as a
jected an additional 600 beyond the face of
'curtain' set externall y, allowing air mo ve-
the columns to pro vide a surface for a main-
ment around it so that when the window
tenance w alkway. The walkway deck w as set
w as open and the study desk in use, the
onto a projecting 'toe' to the facade panel,
screen w o uld pro vide both privacy and
with a metal panel set below the deck to
protection from the w ind. Various studies
The panel can be adapted t o almost any required configurat ion, Versions here include a door or furt her glazing at low er level
were undertaken on levels of refiection of
product, while the outside is sealed in glass
nent to an extemal wall system, or a joinery-
the inner face of the screen to ensurethat it
and aluminium, as well as timber boards in
based approach lacking economy due to a
refiected light rather than making the space
rainscreen configuration if required. This
reluctance to engage with the principles of
behind significant ly darker,
approach could both reduce costs and
economic curtain walling. W all panels could
reducethe weight of panels, making them
also follow the principles of prefabricated
easier to transport and install on site. The
'cassette' fioors where complete sections
The windows usetimber as a material with low thermal conductivity when
framing could be assembled in a similarway
of timber fioor are factory finished, ready
comparedto metals, thus serving as a ther-
to triangulated timber engineered trusses,
for installation on site. This useof prefabri-
mal break in the panel system as well as a
with aluminium or mild steel connectors
cated, yet economic, timber frames exists in
material combined with aluminium for the
pressed into the timber in a similarway
systems for straw bale walls, where straw is
window frames. Greater dimensional stability
to the production of timber trusses. This
encapsulated in a timber frame. In the exam-
could be achieved by using engineered tim-
approach to panel design as a mixture of
ple of this facade system, the timbers would
ber, such as LVL (laminated veneer lumber)
fumiture and curtain walling, could bringthe
remain as part of the intemal construction,
or OSB (oriented strand board), which are
fabrication methods of carpentry and joinery
with curtain walling components remaining
more commonly used in intemal situations,
wit h the technical performance of glazed
extemal.
isolated from the effects of the weather. This
walls, and allowing each part of the design
would allow the structural part of the frame
to reduce costs overall, rather than the fur-
to be made from an engineered timber
niture being an expensive additional compo-
In common with other projects, an aim of the design is to encourage the use of
MCH_ 491
Future 06 I2 Facade with integrated fumiture
A version of the cladding panel wit h a more vertical emphasis. This version includes a moveable mesh shading screen, openings for naturalventilation, heating systems and strorage.
natural vent ilation in facades, which in cross ventilat ed buildings of relatively shallow depth is very useful in the mid season as in summer in cooler climates. The opening windows slide in order t o avoid confiicting with user requirements of the study desks, aswell asthose using the storage space in other panels. The system also allows for full height opaque panels which can be used for storage on their inner face. Storage can also be provided upwards from 800mm above finished floor level, with a glazed strip set at low level in order to wash the floor with light and allow the fitted fumiture to be set above the floor finishes. Full height glazed panels were also designed, providing additional light in spaces with adjacent full height glazing. Here it was assumed that the framing would revert to a primarily aluminium outer frame and timber int emal tri ms, allowing t he floor t o ceiling spanning capability of thin aluminium extrusions to take precedence.
The system was developed further so
MCH_ 492
-
This cladding panel has deep horizontal window revealsto shade the glazing from high sun and a vertical louvre to help protect against a lowersun. The vertical louvre also fonrns part of the extemal drainage system.
that tables could be addedto the sides to adapt its useto university laboratory spaces. This allowed the fumiture wall to coordinate with intemal fittings so that light, heat and electrical power could be provided wit hin the wall panel rather than across the floor of the ceiling. This approach avoided the need for raised fioors and suspended ceilings by servicing the space from the extemal walls, as was the case in other buildings built for the same university in the I960s. There was much to leam from much older facade installations in the university, from the mid 20th century when building systems were undergoing considerable development. The vision in some of these designs of fifty years ago, for the integration of structure, envelope, heating and natural ventilat ion has not been matched in manylater buildings. Not quite the energy hungry 1960s of the popular imagination. This project showed us to look backward into history as well as forward to the future.
MCH_ 493
MCH
495
The glossary of terms here is aimed to
capped joint is used in one direction on a
within a building without direct reference to
explain words used in the context of this
glazed wall, while a silicone seal is used in the
the structural frame.
book.These are not intended to be general
opposite direction. COMPOSITE MATERIALS.These have been
definitions and should be used accordingly. CAVITYWALL.This form of construction
developed to mix two or more different
developed in the I920s onwards in brick
materials together in order to benefit from
Bun JOINTS.These are a contempo-
construction as an alternative to thicker
the strengths of each in order to overcome
rary type of joint where two materials
loadbearing walls, which were both unreli-
the weaknesses inherent in one or other of
are brought together and sealed with a
able in their ability to keep out rainwater
the materials. In wood, for example, where
different material such as silicone, as in an
and vapour as well as being more expensive
a length of timber can span only as long as
external wall.Traditionally, joints in walls
to construct.The cavity wall divides the wall
can be cut from a tree, lengths of timber
Topics are arranged in alphabetical order.
have been formed by some form of lap-
into two halves, orskinsThe outer skin
sections can be increased significantly by
ping, or interlocking of materials, as in the
is the weather barrier, and is assumed to
gluing strips or particles of timber to make
corners of window frames. Butt joints have
become completely soaked during a rain
board material. This combination uses the
the advantage of allowing movement to
storm. The inner leaf is not in contact with
benefits of timber of lightness in weight and
occur in the joint, as where adjacent panels
the outer leaf, so it remains generally dry.
ease of working the material with increased
are supported separately.An example is the
The two skins are joined together with cav-
size and greater stability to reduce the
use of silicone sealant between bolt fixed
ity wall ties, designed to encourage water
effects of moisture movement. Reinforced
glazed units, where double glazed units move
in the cavity from dripping off the ties and
concrete can be regarded as a composite
independently, and may experience consid-
down the cavity rather than being carried
material, with steel reinforcement providing
erable amounts of movement if secured to
onto the face of the adjoining inner skin.The
strength in tension which is lacking in regular
a structure that allows higher deflections
cavity wall has developed by setting thermal
concrete. GRR or glass reinforced plastic, is a
than frames, such as cable net structures. An
insulation either within the cavity, on the
mixture of resins providing, conceptually at
essential requirement of most butt joints is
outer face of the inner skin,or within the
least,compressive strength with glass fibre
to ensure that the there is sufficient surface
inner leaf itself.
giving tensile strength.
seal against,allowing it to stretch in several
CLADDING.This term refers to non-Ioad-
CURTAIN WALLING. This refers historically
directions without losing adhesion.
bearing facade systems which are applied
to glazed wall systems which were 'hung' in
to a building envelope in a way which is
panels or as a metal framework into which
on either side of the joint for the sealant to
CAPPED SYSTEMS. Glazed walls or roofs
independent of the building structure. Clad-
glass panels were set.While the concept is
which are fixed to a continuous framing
ding may even be used to give a completely
clear,these systems are not always hung in
system on all sides are referred to as being
different expression to the building from that
the manner of a curtain, and are not always
'edge restrained'. Since most panels in glass
suggested by either the building structure or
spanning from floor to floor Contemporary
or metal, for example, have four sides,these
the organisation of spaces within the build-
curtain walling is described as being either
systems are generally called 'four edge
ing.This independence of cladding from its
'stick' systems,'unitised' systems,or 'panelised'
restraint' systems,with the panels being held
supporting structure has been exploited
systems (explained under separate headings).
in place by pressure plates. Since the pres-
by many contemporary architects to cre-
Consequently, the term curtain walling is not
sure plates have visible screws which are not
ate textures and geometries which accept
referred to in this book as it is too generic,
always aligned neatly,an additional cover cap
this independence of the technology of the
with 'glazed walls' used instead to allow the
is set on top of the pressure plate.The cap is
building envelope, and work with the oppor-
primary material to take precedence. Cur-
made in extruded aluminium and is coated,
tunities provided by the non-Ioadbearing
tain walling was developed in the years fol-
typically with a colour to match any adjacent
nature of cladding. Since the primary struc-
lowing 1945, primarily in the United States,
metal panels or doors. Such systems are
ture of building is set behind the cladding,
where it was a practical way of enclosing tall
called 'capped systems'to differentiate them
the external envelope can be configured
buildings without the need for lifting heavy
from those which have a silicone seal on the
to give precedence to other design consid-
materials such as stone and brick high up,
outside, such as'toggle' glazing and 'silicone
erations as primary forms of architectural
where they were slow and difficult to man-
bonded' glazing, where only a silicone strip
expression, such daylight, solar control and
age,which became far less economic in
is visible from the outside. Sometimes a
the visual expression of individual spaces
industrialised countries.
MCH
496
EMBODIED ENERGYThis is the amount of
LAPPED JOINTS.This is the traditional
tially two skins of external wall which pro-
energy required to construct a building or
method of forming junctions between mate-
vide a thermal buffer in winter and natural
part of a building. No specific standards can
rials in external walls. In order to ensure that
DOUBLE SKIN FACADES.These are essen-
ventilation in summer.The thermal buffer
be applied yet, as an essential component in
water runs off timber boards, for example,
ensures that solar gain in winter months can
the energy required to construct a building
the material is ship lapped, where one board
be used to heat a building, while in summer,
is the delivery of materials to site, which can
is set over the other. More generally, this
windows at high level can be opened into a
vary enormously, but which favour as local a
principle applies in tiled and slated roofs, and
void between inner and outer skins without
sourcing of materials as possible., in practice
in brick walls where openings are formed so
experiencing the effects of wind gusts.Dou-
this can be difficult to agree, as it needs to
as to lap the external wall around window
ble skin facades can vary from IOOOmm in
be established how far up the supply chain
frames.Where render is used on top of
width, with two walls separated by a main-
to go when calculating the energy required
masonry walls,the render forms, effectively, a
tenance walkway,to a thickness of 300mm,
to make primary materials for a building.
lap between wall and window. Lapped joints
where the double skin is set within a single
In the case of polymers for example, the
are used in contemporary construction
wall construction, typically as unitised panels.
dependence on oil from different parts of
where a butt joint is either not appropriate
With the wider version, comprising two
the worlds being moved around can create
in terms of its exposure or appearance, or
walls set apart, the cavity can be ventilated
complicated scenarios for calculation.Timber
alternatively where ventilation is required, as
form the outside, either with open joints or
is considered to have zero embodied energy
in rainscreen panel systems and roof cover-
with controlled louvres.Thin double skins
as a material, but the energy used to fell, cut
ings. An essential aspect of lapped joints is
are ventilated from inside the building, some-
and transport the material is much higher,
that they are oriented in a direction that
times actually linking the void within the wall
though not as high as the metals used in fix-
ensures rainwater will run off the joint in a
to the mechanical ventilation system.
ings which allow the timber to be made use-
downward direction while allowing ventila-
ful as a building material.
tion to occur in the upward or lateral direction.
EAVES.These are junctions between the top of an external wall and the underside
IN-SITU CAST CONCRETE.This method
of a sloping roof, which typically overhangs
of working with concrete, also called cast-
MEMBRANES.These are single layer materi-
the wall.Where the external wall is made as
in-place concrete, is based on forming the
als made in large sizes, typically I OOOm to
a cladding system rather than a traditional
material on site using formwork that is set
2000mm in width and in long lengths,sup-
loadbearing wall, the relative movements of
up specifically for the casting process, before
plied in rolls.They are made primarily from
wall and roof need to be taken into account
moved to the next stage of casting. The
polymers, and have the advantage of being
in the weather tightness of the junction.
method can be used to create large scale
able to be bonded or welded together, often
There is also a need for continuity of ther-
concrete structures or walls.An important
by heat rather than a naked flame, making
mal insulation from wall to roof, sometimes
consideration is the formwork, which is
them easyto install on site.Their use is main-
providing ventilation into the roof space
used increasingly as a kit of parts that can
ly as reliable waterproof or vapour proof
and sometimes providing a complete seal
be moved and re-assembled quickly for the
layers to large areas of wall or roof which
from wall to roof As an interface between
next part of the work. If the concrete is to
experience relatively little thermal move-
primary elements of a building which are
be a visible part of the construction, as in the
ment.Though reliable, they are relatively
usually performing in quite different ways,
case of columns or external walls,the provi-
fragile unless designed specially for external
using quite different forms of construction,
sion of joints and junctions with adjacent
use,as is the case with thicker, tougher roof-
eavesjunctions require the lapping of the
elements needs to be considered carefully
ing membranes. Mostly, however, membranes
waterproofing for the roof to form a con-
prior to starting on site. Since the casting
are required to be concealed beneath other
tinuity with that of the wall. As an interface,
of concrete reveals very closely the texture
materials to protect them from the effects of
an eaves detail usually requires one of the
of the formwork from which it is cast,the
the sun and from suffering accidental dam-
systems of wall or roof to take precedence
choice of formwork board size, or tube size
age,such as being walked upon for example.
from a visual point of view, so this becomes
for columns, is an essential part of the design
Membranes are usually fixed at points on
an additional requirement of their design.
of the building, and is considered at an early
their underside in order to avoid penetrating
stage of the design.
the membrane.
MCH
497
OPENINGS.This book shows examples of
PANELISED SYSTEM.This is a general term
has some visual presence on the facade and
details around openings as they are often at
covering large scale panels used primarily for
can be seen as a termination of the top of
the interface of different systems,or com-
external walls.Their use is in prefabricated
the building.
ponents from different systems.Windows
wall systems where a building is required
and doors, for example, do not have obvi-
to be assembled on site quickly,or where
POINT FIXED GLAZING. This is a recent
ous ways of being fitted into walls when a
the specific site does not make it easy to
development that originated with clamped
very watertight and airtight performance
undertake complicated work, mainly where
glazing systems of the I 960s, used mainly as
is required. Since facade systems are often
access is restricted. Where unitised panels
shop front glazing at that time.The technique
developed and tested to quite different
in glazed walls are typically around 1500mm
comprises either bolt-like fixings set near
standards and with the intention of form-
wide, panelised systems can be made up to
the corners of the glass, or clamps set on
ing a complete building envelope as a single
around 7000mm long, depending on their
both sides of the glass along the edges of
material system, combinations of two sys-
weight, but are typically delivered to site on
the glass, but not necessarily at their corners.
tems are dealt with on a project by project
trailers, so that transportation is an impor-
An essential part of their design is to ensure
basis. In the case of windows and doors
tant consideration in the design of panelised
that the glass is supported so that it can
being designed within a single system, such
systems.These panels may comprise a
move in order to avoid putting additional
as windows and doors, it is essential in order
mixture of systems,such as metal framed
stress into the glass. These systems are typi-
to understand the visual impact that they
backing walls with windows installed, or even
cally designed in conjunction with a manu-
make on a facade, as well as how they can
precast concrete panels with masonry fixed
facturer or facade designer who can ensure
be accessed for cleaning and maintenance.
or forming an integral part of the panel.They
that the design is suitable both in relation to
Openings are required to be assembled in a
are finding use as waterproofed or vapour
its supporting structure and for fabrication.
particular order if made from different mate-
proofed backing walls which can be installed
Clamped glazing has become more popular
rials or systems,which can infiuence their
quickly on site while the outer skin of the
in recent years since it is more economic
appearance, so the sequence of construction
wall is applied later.This allows the building
than the bolt fixed method, as clamps can be
is a consideration.
to become watertight at an earlier stage of
set between the joints rather than requiring
construction.
glazed units to be drilled to accommodate the bolt fixing.
PARAMETRIC DESIGN.This is an approach to the design of a building, or part of a build-
PARAPETS.These are traditional elements
ing, based on the idea of setting 'parameters'
of buildings which still form a prominent
PRECAST CONCRETE. This material is an
that can be changed dimensionally, while
part of contemporary design. Parapets are
alternative to in-situ cast (or cast-in-place)
making other parts of the design 'fixed',
formed when an external wall projects up
concrete. An essential aspect of precast
which cannot be changed.This principle can
in front of the base of the roof construction,
concrete is that it can be used for structures,
be applied to the geometry of a set of fioor
requiring rainwater to be drained into a gut-
facades, roofs and interior building compo-
slabs, for example, which may be allowed
ter behind the external wall rather than in
nents, making the understanding of how the
to change in one direction only, or be used
front of it.This makes it essential to draw the
material is used an essential aspect of design-
for a set of components which might be
rainwater down the pipes which are typically
ing with the material. Because of the weight
changed.This approach suits geometrically
set outside the building rather than inside,
of concrete and the high amount of material
complex or large-scale projects where the
where they can be difficult to access for
required for its use in construction, its use
time required to rebuild the model would
maintenance an can be susceptible to dam-
as prefabricated components requires care-
be uneconomic. Because parametric design
age,causing leaks. Parapets are detailed so as
ful consideration, particularly in expected
software allows the design to make changes
to form a gutter between wall and roof that
tolerances in its assembly, which can require
quickly, it allows the designers to try changes
can fill to capacity without the risk of leaking
wider gaps than those required in other
to see what happens to an overall building
back into the building. Since parapet gut-
materials. Although precast concrete is used
form, for example.This allows the behaviour
ters can become blocked as a result of the
for staircases, for example, these compo-
of the component or building geometry to
outlet being accidentally covered, the design
nents are often covered up by finishes work
be understood, sometimes linking fioor areas
of these junctions, as well as the provision
and so are not revealed. Consequently, the
to a building geometry.
of overfiows to the outside, are essential
choice of precast concrete over in-situ cast
considerations in their design.The coping, or
concrete may not be of primary interest to
durable covering set on top of the parapet,
the designer in such applications.Where the
MCH
498
use of precast concrete wi II be of concern is
safely when it penetrates joints.The term, in
through the build-up. Some parts of the
where the material is visible, requiring careful
general use, is applied more to open joints
system can perform considerably worse than
attention to finish, mainly in terms of colour
in panel systems,typically metal, timber and,
others, creating a 'bridge' for the passage of
consistency and texture, as well as how the
terracotta than to glazed curtain walls.When
heat or cold which is prevented elsewhere in
formwork will leave traces of the pouring
used in this context, panels in these materi-
the system. In glazed walling, for example, the
method that may, or may not be, required in
als are generally fixed to a framing system
thermal performance of the framing is signifi-
the finished work.
which is secured to the building structure.
cantly lessthan that of the glazed panels,and
A separate backing wall is typically used to
is improved by using a 'thermal break' so that
provide thermal insulation and a waterproof
the high thermal transmission of the frame
PREFABRICATION AND SITE-BASED WORK. The choice between buildings being
layer. Rainscreen panels have grown in use as
is 'broken' with a polymer based component
constructed mainly on site or off site in a
a visually refined facing to economic backing
set between inside and outside. The thermal
workshop or factory is based on issues pri-
walls.
break may be a separating strip or may form
STICK SYSTEM.This is a method of con-
case with aluminium framing to glazed walls.
an integral part of the construction, as is the
marily of cost and quality,though it has also to do with increased specialisation in construction. Projects of ambition often require
structing glazed walls on site from framing
specialist construction skillsto undertake
and glazed units. Stick glazing is often used
U-VALUE AND THERMAL INSULATION.
the construction. Such specialists are usually
in complex arrangements of curtain waIl-
The U-value of a construction is a measure
set up with their own working environment
ing and for smaller projects. Larger projects
of the thermal transmission through the
rather than being based on a succession of
such as apartment buildings often have
material, with systems of lower U-value
building sites.While prefabricated elements
many different conditions in their design on
having higher levels of thermal insulation.
and systems are required to be assembled
the external envelope, which would require
The U-value takes into account the thermal
or set into position on site, this environment
many types of unitised panel that would
transmission of all the layers of construction
is too temporary for many specialists, who
be both uneconomic and difficult to install.
that make up the wall, so walls of different
require a specific planned work environment
Smaller projects do not have a sufficiently
build-up in section require separate U-value
for them to be effective both as an organisa-
large envelope to make unitising panels eco-
calculations. U-values can be used in calcu-
tion and in order to produce work of high
nomic and are usually stick built regardless
lating the rate of heat flow of spaces in the
quality. Quantities of what can be transport-
of their level of complexity. Advantages for
building, but are separate from the effects
ed to site are usually limited by the capacity
designers are mainly the flexibility of design,
of solar gain'through glazing, which may also
and weight allowance of a trailer as well
which does not need to be made modular
cause thermal transmission. Consequently,
as storage facilities on site. However, some
to suit repeated panels,and the narrower
double glazed units have a Low-E coating
building work is more effectively undertaken
size of joint widths, which is usually SOmm
and vacuum in the cavity to provide thermal
on site, using the site as a workshop and
to 70mm depending on project require-
insulation, while a separate solar control
storage facility for components. Structural
ments. Stick systems can also be combined
coating provides protection against the
frames and floor slabs in large scale con-
effectively with supporting steel frames such
effects of solar gain.
struction are still mostly site-based, though
as those for atrium structures and double
the amount of prefabrication is increasing.
skin facades. Where steel frames are used,
UNITISED SYSTEM.This is a prefabricated
the aluminium extruded box section on the
method of making facade panels,typically
RAINSCREENS.These are facade and roof
internal side of the framing can be omitted,
for glazed walls. Its advantage is primarily
panel systems which allow small amounts of
allowing the front part of the stick system to
of reduced cost for facades with consider-
rainwater to enter the joints between panels
be fixed directly to the supporting steelwork,
able repetition resulting in few panel types,
and be drained down through the framing
which would typically be also in box sections.
but another advantage is the use of silicone
back to the outside, either at each floor level . or at the lowest level of the system.The
bonding, allowing frames to appear slim on THERMAL BRIDGING.This is also called
the outside, and for opening lights to have
term was first used for curtain walling, where
'cold bridging' but can occur in hot thermal
their frames concealed internally.Applying
leaks in earlier forms of curtain walling were
conditions as well as cold conditions. Essen-
silicone on site in stick systems can be very
overcome not by attempting to exclude any
tially,the design of different systems of wall
difficult to achieve due to the time needed,
water penetration, but by accepting that it
and roof construction is gradually being
as well as the avoidance of dust around the
is easier to ensure the water drains away
developed to reduce thermal transmission
edges of the bonds.
MCH
499
T his book has been a te am effort involv-
can be manufactured quickly and w it h a
crite ria for t he facades in temperate climates,
ing members of Newtecnic in Lond on.
high degree of accuracy and precision. The
doubl e skin facades are oft en used. Rather
D rawin gs we re mo delled and rendered by
office's current work ranges fro m large scale
than follow rectilinear design, the o uter skin
Michael Clark e, Gerard Ellis, Louise Jarvis,
develo pments in Moscow, D ubai, Egypt,
of facades of projects w here Ne wtecnic
How ard Tee and Adam W illetts. Ad ditional
Kuwa it C ity and St Peter sburg to residential
are involved are required increasingly to be
images w ere generat ed by Roly H udson,
and com mercial projects in London, wh ere
shaped geometrically in response to specific
Maria Sfaellou and Anthony Taylo r.The bo ok
Newtecnic are working w it h design te ams
enviro nmenta l issues.Th ese resulting facade
was designed by Yasmin W atts .The t ext is
t o develop innovati ve t echnical so lut io ns and
form s are t ypically twisted, curved, t apered,
by Andrew W att s,w it h contributions from
optimise complex designs for digital fabrica-
or a co mbinat ion of t hese fo rms.These
Michael Clark e and Louise Jarvis. Michael
tion .
pages aim t o illustrate some of th e research
Clarke w rot e the follo win g t exts: Environ-
Before establishing t heir ow n practice
undertaken by N ewtecnic in recent projects
mental studies for envelope s, Solar radiat ion,
specialising in facades, Ne wtecnic principal s
w hich exhibit the se tendencies in terms of
D aylight, Green walls
Andrew and YasminW atts worked exten-
the possible so lut ions for the design of the
sively both in the UK and abroad. During thi s
cladding in both t emperate and hot climates.
Louise Jarvis w rote the following texts: Straw bales and hemp , rammed earth, co b
time the y w ere involved in a range of signifi-
Th e Ne wtecnic t eam investigates mate-
and ado be bricks, Green oak and bamboo,
cant pro jects including Federation Square,
rial systems th at are explored through 3-D
as w ell as addit ional text for D oubl e skin
Melbourn e wit h LAB Archite cts, th e Millen-
modellin g rather t han 2-D drafting.The
facades.
nium Bridge, London for Foster and Part-
engineering aspects of the design, both
ners, Euralille and Institut du Mon de A rabe,
structural and environmental, are develope d
and Philosoph y at Spr inger Ver lag in Vienn a.
Paris for Ate liers Jean Nouvel, and C it e
t hrough an investigat io n of th e behaviour of
He has driven this book fro m a set of basic
Int ern ationale, Lyon and t he New Caladonia
construction systems w hen mo difed geo-
layo uts to a comp leted book He has a pas-
Cultural Cent re fo r Renzo Piano Building
metrically. Rather than develo p a series of
sion for books and th eir design, ranging from
W orkshop .They have pro duced a numb er
opt ions to solve a design, a single parametric
D avid Marold is Editor fo r A rchite cture
the ir w ider conte nt t o the quality of print
of vol umes o n contemporary building te ch-
model is used w ith fixed criteria and criteria
paper.
nology w hich provide reference material
w hich can be stretch ed and pulled unt il an
N ewtecnic is a firm of Lond o n-based
for student s and pro fessionals.Th e
Modem
opt imum solut ion is fo und.This allows a
specialist archite cts w ho create facades in
Construction Series is publi shed by Springer
collaborat ion with leading archit ects.The firm
Wi en New York In addition, th e
Facades
solutio ns w hich can be explored th rou gh
pr actices internationall y as facade designers
Technical Review, from RIBA Publications
rapid protot ype models,using a range of
for archit ecturally and technic ally challeng-
w as published in spring 2007.
ing projects and has a particular intere st in
Much of Newtecnic's work is informed
developin g new facade systems and in th e
by a specific respon se t o climate and to
single design model t o pro vide a 'range' of
modelling tools from 3-D printers t o laser cutt ers. Strands of fabrication, context, site specificity, language of the base 'com po nent'
use of comp lex geometries. Ne wtecni c fol-
the te chnical performance of t he extern al
of the design and spatial organi sation are
low s pri nciples of rapid prototyping as a
envelop e. In projects w here climat e cont ro l
develop ed in parallel for each proj ect.
met hod of develop ing facade systems th at
and natural vent ilat ion are prim ar y design
MCH
500
Images are credited per page, left to right, and from top to bottom: PIO left. Photo:Adrian Pingstone from Wikipedia. P21 left. Photo: Michael Reeve from Wikipedia. P21 first from left. Photo: julian Nitzsche from Wikipedia. P21 first from top: Photo:Adrian Pingstone from Wikipedia. P40 first from left: Photo:Yoshito Isono from Structurae. P40 second from top. Photo: Lucas B. Salles from Wikipedia. P41 left. Photo:Yoshito Isono from Structurae. P41 first from left. Photo: Finlay McWalter from Wikipedia. P41 first from top. Photo: Enrique Cornejo from Wikipedia. P44,45. Photos: jim Dunster. P47 first from left. Photo:Adrian Pingstone from Wikipedia. P47 second from top. Photo:Adrian Pingstone from Wikipedia. P48Lfirst from top. Photo:Chris McKenna from Wikipedia. P49 first from left. Photo:Olaf Davis from Wikipedia. P50 first from left. Photo: Paul Lechevallier from Wikipedia. P52 first from left. Photo:Walter Horvath from Wikipedia. P52 second from top. Photo: Raul Polanco Montiel from Wikipedia. P56 left. Photo: Marion Schneider & Christoph Aistleitner from Wikipedia. P58 left. Photo: Richard Bartz from Wikipedia. P64, 65. Photos: Don Evans. P66 second from left. Photo: Hubbell & Hubbell Architects. P66 second from top. Photo: Pari iamentary copyright images are reproduced with the permission of Parliament. P66 third from top. Photo: Parliamentary copyright images are reproduced with the permission of Parliament. P67 left and first from left. Photo: Hubbell & Hubbell Architects. P68, 69,70,71. Photo:Architen Landrell Associates Ltd P74, 75.jewish Museum, Berlin, Germany Photos: Courtesy of jewish Museum, Berlin. PIOI. Usera Public Library, Madrid.
Photo: Roland Halbe. P104. Bridgewatchers House, Rotterdam. Photo: Bolles andWilson PI08. Sun Tower Office Building, Seoul. Photo:Youngill Kim. PI I I. Kew House, Melbourne,Carter Tucker house, Victoria, Peninsula House,Victoria. Photo:s: Earl Carter. PI 18. RWE AG Essen, Germany. Photos: H. G. Esch, Holger Knauf P140-141. Matsunoyama Natural Science Museum, japan. Photos: Katsuhisa Kida P206. Uji-anTea house, Tokyo. Photo: Katsuaki Furudate. P275, 276. ETFE images. Photos: Vector Foiltec Ltd. P280, 282 & 283. Canopies. Photo:Architen Landrel Associates Ltd. P284-285. Millennium Dome, London. Photos: Robert Peebles. P288. Photos: jim Dunster P289. Saltwater Pavilion, Neeltje [ans, Holland.Images: OosterhuisAssociates. P290-29 I. jim Dunster. P29 I. jewish 'Museum, Berlin, Germany Photos: Studio Daniel Libeskind. P324. Leipzig Exhibition Centre, Germany. Photos: Busam/Richter. P327. Yatsushiro Municipal Museum, Kumamoto Prefecture, japan. Photos: Toyo Ito & Associates. P322, 337. Photos: Robert Peebles. P342. erner Hall Student Center, Columbia University, New York, USA. Photos: Peter Mauss/Esto (left), Lydia Gould (right). P343. Educatorium, Utrecht University, Holland. Photo: HansWerleman, Hectic Pictures. P344. Okanoyama Museum of Art, Hyogo, japan. Photo:Yasuhiro Ishimoto. P349. Museum of Contemporary Art, Los Angeles, USA. Photo: Yasuhiro Ishimoto. P349. School of Decorative Crafts, Limoges, France. Photo: C. Demonfaucon. P350. Patio houses, Esposende, Portugal. Photo:s LUIs FerreiraAlves. P372. The British School in the Netherlands, The Hague, Holland. Photog: jan Derwig P372. Kew House,Melbourne,Australia. Photo: Earl Carter. P373. lonica Building, Cambridge, England. Images: Battle McCarthy Engineers, London. P374. CarterlTucker House, Breamlea, Victoria,Australia.
Photos: Earl Carter P375. Bibliotheque Nationale, Paris, France. Dominique Perrault. Photos: Georges Fessy. (above), Michel Denance (below). P375.The Menil Collection Museum, Houston,Texas, USA. Photo: Paul Hester © Renzo Piano Building Workshop. P376. GovernmentTraining Centre, HerneSodingen, Germany Photo:Christian Richters. P377. Photovoltaic Installation, Northumberland Building, University of Northumbria, England. Photo: University of Northumbria. P378. Solarchis Solar Houses, japan. Architecture Studio and Maeta Concrete. Photo:Solar. P379. Daggett Solar Farm, California, USA. Photo: G. Donald Bain, Geo-Images Project, University of California at Berkeley, USA. P381 . Strawbale classroom at Avon Tyrrell, New Forest, England. Photo: New Forest ParkAuthority. P382. The Redding Residence, Kendle Design Collaborative, Scottsdale, Arizona Community, USA. Photo:www.eartharchitecture.org P392. Photo: Rob Peebles. P394. RWE AG Essen, Germany Photo:Christian Richters. P395. Photos: Robert Peebles. P396 (left). Kitakame Canal Museum, japan. Photo: Kengo Kuma and Associates. P396 (right). Furniture House,Yamanashi Prefecture, japan. Photo: Hiroyuki Hirai. P397 (left). International Housing Exhibition, Fukuoka, japan. Photo: Kwano, courtesy of the Office for Metropolitan Architecture. P397 (right). Freshwater Pavilion, Neeltje [ans, Holland. Photo: Lars Spuybroek, NOX Architects. P404, 405. Offices, DaimlerChrysler Projekt, Potsdamer Platz, Berlin, Germany Photos: Robert Peebles. P4I2, 4 I 3. Photos: Robert Peebles. P41 6, 417. Mini-House, Nerima-ku,Tokyo, japan. Photos: Tsukamoto and Kaijima. P41 6. Furniture House,Yamanashi Prefecture, japan. Shigeru Ban. Photos: Hiroyuki Hirai. All other photographs have been provided by courtesy of Newtecnic Ltd.
MCH
50 I
A
E
Glossary of terms Green oak and bamboo
A future for building Authorship Aluminium Aluminium windows Arches and shells
416 496 26 144 324
Elevators Embodied energy Energy and the building envelope
Electrical lighting ETFE cushions Exposed membranes Bonded glass rooflights Bolt fixed glazed walls Bolt fixed glazed roofs Brick Brick boxes Brick cavity walls Braced frames
238 132 234 54 312 168 292
GRP panels and shells GRP rooflights
358 396 274 246
226 270 266
H Straw bales and hemp
380
F Fabrics and membranes Fabric systems
68 274
Facade with integrated furniture Fire control
C
Green walls Greenhouse glazing and capped systems
352
Environmental studies for envelopes
B
410 368
492 384 386
Fixed and demountable walls
Internal walls Introduction to Second Edition
484 402 72
Changes from the First Edition Structure of this book
72 4 4 5
Flat roof: Cast-in-situ concrete Cast-in-situ Floor Ceilings Clamped glazing Composite panels roofs Concealed membranes Concrete Concrete block Concrete frames Composite panels Copper, zinc and lead
152 332 80 128 214 242 40 50 292 100 30
Mastic asphalt coverings
sheet membranes Floors Folded glazing Fuel and water supply
Generic wall types
Glass boxes Glass floors
Digital tectonics Double skin facades
364 12 354
Glass roofs
502
Lifts
Glass systems
Liquid based heating/cooling systems Loadbearing boxes Louvre screens
410 388 308 112
M
90 34 136 316 340 226 116
Glazing systems with integral solar shading
MCH
258 78 418 398
G
Glass blocks and channels
Daylight
L
Bitumen-based
Glass
D
254
Maintenance and cleaning Masonry Masonry cavity walls Masonry cladding Masonry rainscreens Masonry loadbearing walls Metal solar shading: louvres and mesh
454
404 48 168 176 180 164
Material systems for structures
424 288
Mechanical heating/cooling systems Mesh screens Metal louvres roofs Metal standing seam walls Metal walls Moving shading panels
390 108 222 206 92 442
S
Sheet metal walls
400 92
Single membrane: cone-shaped roof Single membrane: barrel-shaped roof
Natural ventilation
Small precast panels Solar power Solar heating
P
Solar radiation Solar shading and daylight controls
Passive design Photo credits Pitched roof:tiles Planted roof Plaster systems Plastic-based cladding Plastic rainscreens Plastics and composites Portal frames
372 497 262 250 74 184 188 58 304
466
for facades of complex geometry Precast concrete floors Profiled cladding Profiled metal sheet roofs
448 334 96 210
Space grids Concrete Steel Timber Glass Steel Steel mesh floor Steel frames Sticksystems Stickglazing for double facades Stone Stone and block walls Storey height precast Structure and envelope complex geometry
Rainscreen walls
Timber windows
148 430 84 202 320 436
Timber Timber floors Timber roofs
Triangular panels for twisted facades Trends in facade design Trends in roof design Trusses Twisted facades
342 344 346 348 22 336 296 140 120 460 52 172 156 10
U
124
Unitised glazing
V Variable concrete panels for
472
solar shading
W
Structural facades of
R
Rainscreens roofs
192
Tectonics in plastics
Timber cladding panels
230 278 282 160 376 378 360 374 328
Stairs:
Steel windows
Precast concrete panels
Timber framed walls
Tectonics in masonry Tectonics in timber
Shingled glazing for facades of complex geometry and rooflights
372
Timber frames
Tectonics in concrete Sanitation and drainage
Silicone-sealed glazing
N
32 38 46 56 62 64 196 338 254 300
Tectonics in glass
218 104
Support services
382 308
T
478 400
76
Wallboard systems
Rammed earth, cob and adobe bricks Reinforced concrete boxes
Taxonomy of material systems Parametric design Tectonics in metal
8 16 20
MCH
503
Andrew Watts London, England
This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically those of translation, reprinting, re-use of illustrations, broadcasting, reproduction by photocopying machines or similar means,and storage in data banks.
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© 200 1,20 I 0 Springer-VerlagNienna Printed in Austria SpringerWienNewYork is a part of Springer Science+Business Media springer.at
The publisher and editor kindly wish to inform you that in some cases, despite their best efforts to do so,they did not succeed in clarifying the copyright for text excerpts used.
Layout and Cover Design: YasminWatts, London, England Cover photo: Helene Binet Proofreading: Andrea Lyman,Vienna,Austria Printing and binding: Holzhausen Druck & Medien GmbH, Vienna,Austria
Printed on acid-free and chlorine-free bleached paper
SPIN: 12090631
Library of Congress Control Number: 200 I042058
With numerous (partly coloured) figures
ISBN 978-3-211-99195-4 SpringerWienNewYork
MCH
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