ETFE is short for Ethylene Tetra Flouro Ethylene, which is a transparent polymer supported by a cable net system or a series of inflated cushions. This type of roofing is an increasingly popular alternative to glass and plastic for large spans over commercial and public buildings, as well as for building facades. It transmits more light than glass, provides better insulation, and costs less to install (24% to 70% less). How strong can a foil material be, you ask? Strong enough to support 400 times its own weight and to last 50 years.