Single Ply Roofs in Tyler
Thermosets - Single-ply membranes can be generally categorized into two groups – thermosets and thermoplastics. Thermosets, or those materials that you can’t hot-air weld because it will change their physical characteristics, use a tape or a contact cement to make up the lap. Thermoset membranes are compounded from rubber polymers. The most commonly used polymer is EPDM [ethylene propylene diene monomer].
EPDM membranes are known for their long-term weathering ability, and perform well even when subjected to fluctuations in temperature, ultraviolet rays, and ozone. The membranes are available in both unreinforced and reinforced, the latter of which increases resistance to tearing. EPDM is available in thicknesses ranging from 30 mils to 90 mils, and is offered in wider sheets that may be desirable. EPDM may be a good choice because you can get it in sheets up to 50 [feet] by 100 [feet]; for very large roof areas, it’s an ideal product to minimize the seams,” says McFarland. While it’s true that wider sheets can reduce the number of seams on a roof, there has been some debate about whether long-term wind resistance could be compromised in mechanically fastened applications where wider sheets are used.
Although most people think of thermoplastic membranes when a cool roof is mentioned, EPDM membranes can be energy-savers, too. By applying white, acrylic coatings, the transformation of an EPDM roof is like night and day. In addition to the oils and polymers used to make an EPDM membrane, another ingredient is added to the mix to enhance UV resistance. In the case of a black membrane, carbon black is added, which converts UV rays into heat. In the case of a white membrane, in lieu of carbon black, titanium dioxide is typically used to reflect UV rays and prevent it from attacking the polymer.
Hypalon is another thermoset, although it is quite different from EPDM. Hypalon is a unique material because it is manufactured as a thermoplastic; but, because it cures over time, it becomes a thermoset. Hypalon materials are heat sealed at the seams. It’s important to note that, unlike thermoplastics, Hypalon becomes unweldable with age.
Thermoplastics - As opposed to thermosets, which must use adhesives, the seams on thermoplastic single-ply membranes can be hot-air welded together to form cohesive laps. When thermoplastic membranes cool, they return to their original material type. PVC and TPO are two of the most commonly installed thermoplastic single-ply membranes. Most thermoplastic membranes are manufactured to include a reinforcement layer, usually polyester or fiber glass, which provides increased strength and dimensional stability, and because these membranes are characteristically light in color, they provide excellent reflectivity, resulting in potential energy savings.
PVC membranes are manufactured from a combination of PVC resin, stabilizers, pigments, fillers, plasticizers, biocides, and various processing aids. Unlike TPO membranes, which require additives to increase fire resistance, PVC membranes are naturally fire retardant. While problems back in the 1960s with PVC membranes may have colored some facilities professionals’ views on these thermoplastic roofs, the use of chemical plasticizers that evaporated (causing embrittlement and shrinkage) have long since been discontinued.
The other popular thermoplastic membrane on the market today is TPO. TPO polymers are blends or alloys of polypropylene plastic or polyprolylene and ethylene propylene rubber (EPR) or ethylene propylene diene terpolymer rubber (EPDM). TPO can be installed in a multitude of ways and with the introduction of peel-and-stick products, installation time can be reduced significantly. Like PVC, TPO remains hot-air weldable throughout its service life, simplifying repairs and maintenance.
