Single-ply is wide sheeting meant for low-slope roofs. They have far fewer seams than asphalt or other rolled roof systems and they come with prefabricated detailing accessories that make installation easy. To fully appreciate the advantages of single-ply roofing, we need to take into account the variations in the product and how they are produced.
Ethylene Propylene Diene Monomer (EPDM) is a synthetic rubber most commonly used in single-ply roofing because it is readily available and relatively simple to apply. Raw materials used to create EPDM include equal parts polymer and carbon black for UV resistance, comprising about 50 percent of the formula, while the rest is made up of materials for processing, fire resistance and stability. EPDM materials are prone to shrinkage, which allows the laps and seams to become a source of water infiltration.
Hypalon is a membrane-based and reinforced synthetic rubber, also known as Chlorosulfonated Polyethylene (CSPE), which is a product of DuPont Performance Elastomers, a subsidiary of DuPont. It is a single-ply system that offers better chemical resistance and UV stability than
other single-ply systems, with a life expectancy of around 17 years. Unfortunately, it suffers from the same issues that EPDM roofing does in that it is prone to shrinkage.
Polyvinyl Chloride (PVC) 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). PVC sin is modified with plasticizers and UV stabilizers and reinforced with fiberglass non-woven mats or polyester woven scrims. This flexible roofing membrane is then sealed with heat-welded seams, forming a permanent, watertight bond that is stronger than the membrane itself.
Thermoplastic Polyolefin (TPO) is manufactured by polymerizing polypropylene with ethylene- propylene to enhance durability. It is then combined with fire retardants, UV stabilizers, antioxidants, and pigments to produce roofing membranes. These are a popular choice for “green” buildings as there are usually no plasticizers added and TPO does not degrade under UV radiation. TPO seam strengths are reported to be three to four times higher than EPDM roofing systems.