A secondary roof membrane to be available on the market was introduced in Europe in the 60’s. PVC, another thermoplastic membrane available in a variety of thickness’, has been installed in the US since the 70’s and has found an increasing market share since that time.
PVC is specifically polyvinyl chloride and is formed into membrane with the addition of oils or liquid plasticizers. In roofing membranes, PVC is available in “bare” form or with the addition of fleece backing. PVC has a superior resistance to ponding water and chemical resistance is high. Additionally, many PVC roof membranes such as Sarnafil, qualify as Energy Star rated for reflectively and meet the EPA and DOE energy savings specifications. Most PVC membranes can be formed in a spectrum of colors allowing for a metal panel “look” or the addition of logos or multi-colored systems.
As with most single-ply membranes, PVC is attached mechanically through insulation, direct to substrate, or may be fully adhered. With the addition of fleece backing materials, PVC can be fully adhered over rougher finishes or mopped with asphalt. The laps are made similarly to TPO or CSPE membranes by using robotic or hand-held welders that force heated air into the laps and fuse them together in a semi-molten state. These laps are then rolled as part of the electric welding process, yielding one continuous membrane.
Two significant problems with PVC membranes have appeared over the years. The first is plasticizer migration. This causes the membrane to embrittle, shrink and become a candidate for shattering, especially in cold weather. Many of the oils and liquids initially used in fabrication exhibit this trate and shattering at 22 degrees Farenheit is documented. If this occurs, it is mandatory to re-roof immediately since there is no way to re-establish the plasticizer content. The addition of polymers such as Elvaloy is Sarnafil and Fibertite membranes and the use of reinforcement fiberglass or polyester fibers have addressed this problem.
The second problem is that PVC manufacture and its’ components are inherently environmentally unfriendly. Accounting for nearly 40% of the worldwide chlorine production, PVC also produces biohazards at almost every stage of the life cycle from fabrication – disposal. Numerous nations and communities have PVC avoidance policies which extend to roof membranes.
To discuss preventive measures or inspections of your PVC roof, please contact All Area Roofing. One of our specialists will be glad to help you.
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