Single-ply roofing is essentially any flexible sheet of compounded plastic-derived material that is used to protect and cover flat and low-sloped buildings. Not all single-ply roofing options are identical, but they do share some basic properties.
The three primary types of single-ply roofing are Polyvinyl Chloride (PVC), Ethylene Propylene Diene Monomer (EPDM), and Thermoplastic Polyolefin (TPO). PVC single-ply roofs have been in use the longest, and are still a popular option, although TPO and EPDM currently lead the industry.