PVC (Polyvinyl Chloride) Membrane
PVC, also commonly known as vinyl, is composed of two main components: ethylene and chlorine. Petroleum or natural gas is processed to produce ethylene, while chlorine is derived from salt. In the compounding process, vinyl resin is blended with plasticizers, heat-stabilizers, ultraviolet (UV) light inhibitors, biocides, and color pigments.
A PVC roof is a single-ply membrane composed of two layers of PVC material with a polyester reinforcement scrim in between. The top ply contains special additives that make the membrane UV resistant and prevent curing. Additionally, the top ply contains plasticizers that make the membrane flexible and pigments for color. The bottom ply is a black PVC, containing more plasticizers for flexibility and typically no other additives or fillers. Additionally, polyester or fiberglass reinforcement is added to achieve high tearing and breaking strengths necessary for mechanically fastened single-ply roofing systems.
PVC roofs are distinguished by the way they are put together, using hot-air welding (fusion welding) of the seams. Hot – air welding creates a permanent physical bond between the sheets that is actually stronger than the membrane itself, making PVC roof installation fast and ensuring that critical areas are permanently watertight. Moreover, hot-air welding also ensures that the membrane will remain pliable and will be impervious to leaks, even if there are puddles of water on the roof.