Single-ply roofing is classified as flexible sheets of compounded plastic-derived material that are used to cover and protect flat and low-sloped buildings. Some common single-ply roofing systems are TPO, PVC and EPDM materials. Properly installed, single-ply roofing systems offer an inherent advantage over traditional materials due to their strength, flexibility, and high durability. The fastening methods for single-ply are mechanically attached, fully adhered or ballasted.