What is PTFE Fiberglass Membrane: Polytetrafluoroethylene (PTFE) coated fiberglass non-ventilated fabric is a membrane and the most durable fabric on the market. PTFE coated fiberglass provides uncompromised and unequaled beauty, longevity, and functionality. PTFE was developed in 1938 and has been used in building applications since the 1970s.