Fabrics are woven materials. They have warp threads, which are stretched lengthwise in the loom, crossed by weft threads.
In general terms we exploit three types of fibre: Natural – e.g. cotton, hemp, flax and glass fibres; Synthetic – e.g. polyesters, para-amides (Kevlar®), carbon; Metal Fibres – e.g. copper, stainless steel
The fabrics we use in architecture – buildings rather than camping and expedition tents – can be categorised broadly into three application areas:
In principle, any of the above fibres can be used in any of the three application areas, but some are more appropriate than others.
Structural Applications – Glass fibre and polyester cloths
For structural applications it is necessary to have available precise and predictable warp and weft properties such as tensile strength, tensile modulus and tensile elongation at break. These fabrics should not be confused with PVC (polyvinylchloride) sheet, a non-woven material which is used for very small umbrellas and canopies. PVC is considered environmentally un-friendly.
Structural fabrics can be classified into permanent and temporary structures. In the last thirty years, there has been a tendency to move away from plant fibres to those made from glass and synthetic materials. Nowadays, the structural fabric cloth is either glass fibre (electrical grade) or polyester which is then coated to create a waterproof material. The coating should be resistant to ultra-violet radiation and ideally self-cleaning. We have not included small scale expedition tent materials.
Permanent coating materials include PTFE (polytetrafluoroethylene), often referred to as Teflon®, (and) ETFE ethylenetetrafluoroethlene, and silicone on glass cloth. Coatings on non-permanent polyester cloth include PVC and PVDF, to which inert laquers can be applied to improve their lifespan.
Other structural fabrics can be manufactured which do not serve as weather or waterproof enclosures and these are used as the lower surface of double skin fabric structures. Also, very open weave glass fibre can be bonded to materials such as PVF (polyvinylfluoride), also known as Tedlar® to create quasi-structural vapour barriers in such double skin fabric structures which incorporate insulation.
Between the domes and the outer rectangular edge of the flat roof is tensioned, insulated double-skinned permanent fabric roof. This was the first insulated fabric roof which not only met the thermal insulation codes (1983) but which also transmitted natural light.
The outer and inner fabrics, separated by approximately 60cm, were made of PTFE coated glass fibre. The outer fabric cloth was a heavier and stronger weave, being subject to higher live loadings.
The insulation was a white spun fibreglass – Fibair®, whose particular characteristics of shape memory and light transmission without changing the colour of the light made it an ideal material for this prototype roof. The vapour barrier was made of glass fibre reinforced Tedlar®.
RFR were asked to develop a new permanent structural fabric that would transmit up to 50% of light and not be subject to the patent premiums of using Teflon®. This was achieved through a joint research project involving Brochier Aerospatiale, Lyon (woven glass fibre), Solvay, Brussels (transparent -trifluoroethylene film) and PTL, Lyon (cold lamination of the film to the glass fibre).
Earlier design research projects included a tent for a Trans Canadian Expedition in 1982, in which we, with Tom Barker of Arup, sought to develop a very lightweight multi-skinned enclosure capable of transmitting moisture (breathing, sweating) from within to without. With the advance in high performance breathing fabrics, this is now possible.
Fabric structures we have designed with Peter Rice/Arup include the temporary exhibition/event hall at the Alexandra Pavilion in London (1980-85) and the Shelterspan System MkII (1979-86). Other projects which incorporate elements of structural fabric include EAGLE ROCK (1979), ALBERT CULTURAL CENTRE (1990), DAOURS PRIMARY SCHOOL, WHITE CITY(1998) and the HAWKING SPACETIME CENTRE (1999).
External Protection – Aluminium coated polyester
FLUY House used an aluminium coated woven polyester material for the solar blinds. The material was developed for the NASA space programme, specifically as a clothing material. Its two main advantages were that the aluminium had a high reflectance and because the coating did not fill the space between the fibres, it was possible to have a reasonably good view through it. However, after several years exposed to the elements, they began to rip in high winds. They were replaced in 1988 by a glass fibre woven material – solarscreen, then marketed by Colt International.
In 1985-86 Ian Ritchie led the research initiative on behalf of RFR to develop a new ‘permanent’ and 50% light transmitting fabric in collaboration with Brochier Aerospace, Solvay, Brussels, and PTL, Lyon. The resultant product is based upon a trifluoroethlene film manufactured by Solvay being cold bonded under high pressure by PTL to a glass cloth manufactured by Brochier. It was manufactured during the 1980s and early 90s.
Since the mid-1980’s, woven metals have been used architecturally. These include stainless steel and, more recently, copper and phosphor bronze fabrics. They have been used expressively in architecture for ceilings, space screens, solar shading, rainscreens and landscape supports.
We used this project to experiment with a woven metal – Becobelt®. It was used to provide support for plants and as an aesthetic screen on the two flank walls. Until then, Becobelt™ was an industrial product used for collapsible lift gates and horizontal conveyor belts.
This project proposed a revolutionary new structure based upon woven titanium. The company Brochier Aerospatiale, which had developed the three dimensional glass fibre prototype for Concorde’s nose, were also capable of weaving in two and three dimensions fibres such as carbon, boron and titanium. We had found this company through our research (RFR) into producing a new permanent structural fabric for the La Villette Roof.
Stainless steel Becobelt® panels were designed as protection elements of the roof facades. Much later (1998), additional security components, also made from Becobelt® were added.
We proposed a different density version of Becobelt® to retain the loose stones of the of the flank walls of the proposed opera house at Tower Bridge. The design of these walls was an attempt to achieve a perceived aesthetic and material change of a new type of gabion wall. The view perpendicular to these walls was of stone, however, the more tangential the view the more the wall became a shimmer of stainless steel. The mock-ups proved the potential to create a strong visual dynamic.
where substantial areas of the external walls will be made of woven phosphor bronze.
where spatial illusions and illuminated surfaces between “worlds” will be created using tailored and tensioned woven metals.
The structure is simple, consisting of 2 cantilever tubular members, a cable net, and foundation bases. The fabric is wrapped around the tubes and is supported between them by the cable net. The cable net consists of 10mm diameter stainless steel cables at 1200mm centres spanning between the tubular members. It transfers the fabric weight, and any wind and snow loads to these members. The cable net is a ‘loose fit’ design to allow the fabric to react to the wind and snow loads.
The optical glass fibre bundles are protected by a transparent casing which will not degrade under ultra-violet light, extreme temperatures, urban pollution or be damaged by insects or bird attack. The submitted sample fabric panel will be structurally reinforced with additional stainless steel woven thread. Maintenance of the fabric is limited to cleaning with a water jet.
Based on our experience with lightweight structures and project management, various industrial facilities have been designed and built using the Shelterspan fabric structure. The built examples have been based on our development with Peter Rice, of Ove Arup and Partners for Shelterspan of an aluminium frame and pvc coated polyester fabric structure.
These have been exploited for several different types of use:
and erected in England, including the GLC Inner London area, and Scandinavia between 1978 – 1982 at a constructed average cost of £2.50/sq ft!