Specialists in industrial roofing and energy efficient solutions
Polyvinyl Chloride (PVC) membrane roofing is also known as vinyl roofing. Vinyl is derived from two simple ingredients: fossil fuel and salt. Petroleum or natural gas is processed to make ethylene, and salt is subjected to electrolysis to separate out the natural element chlorine. Ethylene and chlorine are combined to produce ethylene dichloride (EDC), which is further processed into a gas called vinyl chloride monomer (VCM). In the next step, known as polymerisation, the VCM molecule forms chains, converting the gas into a fine, white powder – vinyl resin – which becomes the basis for the final process, compounding. In compounding, vinyl resin may be blended with additives such as stabilisers for durability, plasticisers for flexibility and pigments for colour.
Thermoplastic PVC roofing is extremely strong, as its heat-welded seams form a permanent, watertight bond that is stronger than the membrane itself. PVC resin is modified with plasticisers and UV stabilisers, and reinforced with fibreglass non-woven mats or polyester woven scrims, for use as a flexible roofing membrane. PVC is, however, subject to plasticiser migration (a process by which the plasticisers migrate out of the sheet causing it to become brittle). Thus a thicker membrane has a larger reservoir of plasticiser to maintain flexibility over its lifespan. PVC is often blended with other polymers to add to the performance capabilities of the original PVC formulation, such as KEE – Keytone Ethylene Ester. Such blends are referred to as either a CPA – Copolymer Alloy, or a TPA – Tripolymer Alloy.
Benefits of PVC
- Inherently fire resistant (due to chemical composition, have broader range of fire ratings over common substrates)
- Been sold for commercial roofing use for more than 60 years
- Long life cycle – and associated lower energy consumption to both produce the raw material and process it into useful products – sustainability
- energy-efficient roofing option due to their inherently light colouring (While the surface of a black roof can experience a temperature increase of as much as 90 degrees under the heat of the full sun, a white reflective roof typically increases only 10-25 degrees Fahrenheit)
- Can also be used in waterproofing applications for roofing (A common technique used in association with green, or planted, roofs)
It worthy of note that many Green Building organisations recommend not using PVC roofing due to significant environmental hazards from the toxicity of the manufacturing process as well as the noxious compounds released in a fire such as hydrochloric acid fumes and byproducts including dioxin, a potent carcinogen.