Building With Fabric – Material Choicesbedewy
Today’s Architect has a tough decision to make when it comes to choosing materials. There is steel and glass and concrete and wood. What about fabric! Architectural Fabric Structures are fast becoming a very common and visible part of the built environment. No longer used for garden parties and traveling circuses, these structures come in many new forms and uses.
Fabric structures are being designed for as few as one person as in a boutique resort hotel in the outback of Australia, to covering 50,000 plus at the Super Bowl in Houston, Texas. Fabric Structures are now also being designed to cover animals as well like at Seaworld, Orlando where these structures cover dolphins to prevent them from sun burn (they get sun burn too?). And let’s not forget Man’s newest best friend, the automobile. More and more, the automobile has taken center stage where valet parking attendants, airport parking owners and car dealers are discovering the advantages of covering automobiles.
Fabric Structures are beings used as roofs, sails, walls, lights, shades and even signs. With all these different uses and forms, there are a variety of materials to choose from depending on one’s needs, budget and design.
The best way to determine which material to use is to see what has already been used for the building type you are considering.
If you are interested in structures such as tents or umbrellas where the main objective is to provide temporary, nomadic shelter, you are probably looking at vinyl laminated or coated polyester.
If you are researching awnings and canopies, the options are endless. You are most likely to hear words like acrylic canvas and backlit fabrics and materials which you can apply graphics to.
If shade is your primary concern, the buzz word is structural mesh, high density polyethylene (HDPE), perforations and percentage of light transmission.
For warehousing, industrial applications and temporary buildings, a common term may be clear spans or pre-engineered fabric building with materials that are mold and mildew resistant like polyolefin.
The interior and lighting industry have their own variety of fabrics where flame resistance, UL ratings and percentage of reflectance are the most important issues.
Air and Tension Fabric Structures rely heavily on the fabric’s structural characteristics so tensile strength, sound absorption and solar transmission play a major role in their selection.
So, What material do you use?
Is your project near the water? Is it meant to last 20 years? Do you want to see it from afar or do you want it to be dark inside at noon? These are all important questions one should answer before you even start. Fabric Structures have very few components. In most cases, it is just steel, fabric, cables and hardware. The choice for each component will most certainly affect the others. Other issues include: span, size, availability, cost, codes, etc.
In most States, permanent, totally enclosed structures require a “non combustible” or Class A/B rating according to Building Codes. The most recognized and accepted material used for Architectural Applications is Teflon Coated Fiberglass or PTFE.
Recognized manufacturers include Saint Gobain, Verseidag, FiberTech and Taconic. Teflon comes to the site brown like a pair of khakis but bleaches to a milky white over time (usually 4-8 weeks). The biggest problem with Teflon is that it is stiff and brittle and must be handled very carefully to avoid breaking the fibers. The best part is its life span (25+ years) and its “self cleaning” attributes.
Other “non combustible” materials include Silicon Coated Fiberglass, Gore Brand Tenara Architectural Fabrics and Ethylene tetra ethylene or ETFE.
Silicon has been out on the market for quite some time. Unlike Teflon coated fiberglass which can be heat welded, Silicon must be glued with a special adhesive. The advantage of silicon over Teflon is its translucency, cost and availability of colors. Gore Brand Tenara is also in the “non combustible category”. Its advantages include its high translucency, long life span and it is more pliable than silicon or Teflon so it can be used for retractable structures.
ETFE is not really a fabric but a film presently being promoted as an alternative to structural glass. It is “green” friendly and is the new hot material to Architects world wide today. It is being used in FIFA Stadiums in Germany, the Olympic Games in China, being specified for commercial buildings and retail and the choice for creating artificial rainforests for zoos and Science Centers.
The majority of fabric structures being considered today are for uses which do not require complete enclosure. That means, they are most likely “open air” or do not require a Class A rating. Class C is the most common rating and NFPA 701 is the most accepted certificate for most Fire Marshals. Vinyl coated polyester (PVC) is the most common material used on the market today.
What’s not to like. The material comes in a variety of colors, strengths, weights, thickness, perforations, translucency and textures. The material is pliable and stretches quite nicely. You can find material with 10, 12 and even 15 year warranties. You can find material that is 50 to 100″ wide so you can have few, fewer or the fewest amounts of seams.
Manufacturers include Ferrari, Mehler, Naizil, Seaman and Verseidag, to name a few. These are the names most seen on Specifications, which means that these companies are directly marketing and assisting the Architect in the early stages of the design.
PVC comes in a variety of top finishes: acrylic, PVDF and PVF film. There is much debate about top finishes but all manufacturers agree that they are needed to protect the base fabric from UV degradation, water and wind. Frankly, it’s all about the coatings. PVF is a film applied to the main fabric while acrylic and PVDF are coatings. Both PVF and PVDF claim to be “self cleaning” or provide the base material with a much cleaner and maintenance free surface but both require additional work in the shop which may be unknown to the Architect. Both top of the line PVF and PVDF require that the top coat or film where two panels are to meet be grinded off in order for them to be RF welded. This is time consuming and requires great care in order to keep the seams clear of dirt, model and mildew. There are “weldable” PVDF but their warranties are not as long as the high tech top coats.PVC Structures love graphics and provide a great backdrop for projected images.
Today, more and more fabric structures are being designed for shade only. Structural mesh and perforated fabrics are being specified because of the need for shade, the need to allow the elements to go through the material and the need for a space to “see through and be seen”. The material most often used is high density polyethylene (HDPE). Manufacturers include Multiknit, Coolaroo and Shadetex. This material is a higher grade mesh than what one would see at a home improvement warehouse or at an outdoor furniture store. HDPE is used for playgrounds, areas requiring hail protection, schools, day care centers as well as theme parks and spaces of public assembly. Mesh is hot so you can stay cool. Mesh comes in colors, fire rated and with different perforations. It has a life span of 8-10 years and in most cases lowers the size and loads on the structural system and foundations because it takes less wind.
If you want to keep it simple, then work with materials which do not rely on their structural characteristics for its stability. These materials are usually clad on a frame. The materials are usually vinyl laminated polyester, acrylic coated canvas, and materials with a light topcoat. Sunbrella is a common brand name. The material has less technical information available for applying them to fully engineered lightweight structures but when used as a cladding on a frame, they offer many opportunities to the Architect. One can apply graphics to the material, bring texture to the surface or make something truly unique.
If you want to look at materials for interior application, look no further than the industrial fabric industry and Theatrical Drapery. There are lightweight PTFE materials used for ceilings in dome stadiums, PVC fabrics are used for interior tensioned fabric sculptures while theatrical drapery materials from companies like Rosebrand and Dazian are used for a softer look. Spandex/Lycra is another common material used for transforming temporary and permanent spaces but require the material be fire treated prior to fabrication.
Lastly, it doesn’t hurt to dream about the future of architectural fabrics. The wish list would include “Smart” fabrics, fabrics that change color according to weather, light or mood. Fabrics made with optic and photovoltaic fibers, materials with longer life spans, higher tensile strength, improved self cleaning, higher translucency and environmentally friendly.
The future of Architectural Fabric Structures depends on the continuing effort of manufacturers to improve its existing products and to introduce new materials.