Single ply roofing systems are designed to be installed in both residential and commercial buildings with flat roofs. Single ply membranes are easier, faster and safer to install than conventional modified bitumen or built up roof systems. They are also lighter than asphalt based systems thus causing less stress on roof structures. Single ply systems are versatile and can be installed over your home’s existing roof by using either coverboard or rigid insulation in order to obtain a smooth compatible surface. By using rigid insulation you can also obtain more R-value for your home thus reducing yearly energy costs drastically. Thermoplastic Polyolefin (TPO) and Polyvinyl Chloride (PVC) are the most common single ply materials used today each designed to perform well in low slope roofing. Both TPO and PVC membranes are given their waterproof integrity by hand and robotic heat welding of seams.  Here are some of the differences of both TPO and PVC Single ply membranes.