PVC roofing membranes continue to be the leading product in both commercial and residential flat roofing market. To get a better sense of why PVC is a superior roofing system, besting its competitors in quality, durability, and longevity, it is important to know a brief history and evolution of PVC roofing membranes.
PVC ROOFING 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.
HOT – AIR WELDED SEAMS
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 ponding water on the roof.
HISTORY OF PVC
PVC is one of the pioneering single-ply roof materials that was specifically designed to address a wide range of roofing problems resulting from water leaks. In 1966, a German company, called Trocal, formulated and produced the first known PVC roofing membrane. PVC’s superior performance to other flat roofing systems were quickly recognized, and within a few years, Trocal’s PVC roofing membranes covered millions of square feet all over Europe and the use of PVC membranes started spreading across the world. In Europe, PVC roofing membrane continues to be the leading single-ply roofing material, boasting the longest track record of successful performance of any thermoplastic membrane.
30+ years of performance without failure:
It took less than a decade for PVC roofing membranes to start being produced in the US instead of being imported from Europe. However, initially a number of US manufacturers producing PVC membranes made a critical error in the formulation of the membrane in the effort to make the process more economical. Specifically, because PVC is not a naturally flexible material, it requires the addition of a number of plasticizers to gain an appropriate level of flexibility. To save money, manufacturers changed the formulation and started adding less of these plasticizers, which lead to failures of these newly formulated PVC membranes. The membrane simply reverted to its original inflexible state and started shattering during cold weather.
After massive recalls, US manufacturers have improved the formulation, adhering to the strict standards of their European counterparts. The two oldest and most reputable PVC manufacturers in the US are Sika Sarnafil and IB Roofing Systems. Both manufacturers use a time tested PVC formulation that they have not changed for years, guaranteeing the durability and longevity of their product. Since these improvements have been made over 30 years ago, PVC roofing membranes are known to be the most reliable and long-lasting single-ply roofing systems.