Almost all permanent fabric structures built today are entirely synthetic. The most common fibers used for the membrane are fiberglass or polyester. Fiberglass is strong and durable but deteriorates when exposed to moisture. Polyester is less expensive but it is not as strong and degrades when exposed to sunlight. Silicon rubber and Teflon are usually used to coat these materials.
The fabric is not made and shipped in one piece. It is made in sheets, usually about 12' wide and varying length. The easiest and most common method of joining the fabric together is the standard lap joint. The two pieces of fabric are overlapped by three inches and Teflon FEP film is inserted between them. The joint is then heat welded together. When completed, the joint is stronger than the fabric, and completely water and air tight.
Cables are usually made from steel, because it has a low cost, availablility, and long life. Kevlar and glass fiber cables are stronger and stiffer, but are more expensive and degrade when exposed to ultraviolet light.
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