This topic includes information related to thermoplastic polyolefin roofing installed during construction. Thermoplastic polyolefin roofing is a type of roofing commonly used on commercial roofs to keep rain water from entering a structure. Single-ply membranes are manufactured from ethylene propylene rubber and available in white, gray or black. Thermoplastic polyolefin roof membrane is either fully-adhered, mechanically fastened or ballasted to a roof surface.