Thermoplastic polyolefin, or TPO, roofing is a thin, rubberlike, single-ply sheet membrane material that’s been used since 1989 for roofing commercial and industrial structures. The raw TPO resin is mixed with materials to resist weathering and fire, and white pigments for color, and then rolled into thin sheets that are bonded to the top and bottom of a polyester fiber core to make roofing material that can withstand the elements.
TPO waterproof roofing is laid on top of a built-up roof structure of corrugated steel decking, rigid foam insulation and roofing board. It is available in thicknesses of 1.1 to 2 millimeters and is supplied in rolls up to 12 feet wide. It can be nailed down with special mechanical fasteners or glued down with special adhesives formulated for roofing. Adjacent sheets are welded together with a heat gun blasting hot air at 1,000 degrees Fahrenheit to form a watertight roof.