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What is EPDM?
June 10, 2016
EPDM (ethylene propylene diene terpolymer) is an extremely durable synthetic rubber roofing membrane widely used in low-slope buildings. Its two primary ingredients, ethylene and propylene, are derived from oil and natural gas. EPDM is available in both black and white, and is sold a broad variety of widths, ranging from 7.5 feet to fifty feet, and in two thicknesses, 45 and 60 mils. EPDM can be installed either fully adhered, mechanically attached or ballasted, with the seams of the roofing system sealed with liquid adhesives or specially formulated tape.
Expansion and contraction, ponding, moisture, thermal shock, and temperature extremes are all factors that promote premature degradation of a roofing membrane. The great elongation and low temperature flexibility of EPDM membrane accommodate building movement in various climatic conditions without stressing the material. Its moisture absorption resistance allows the material to be installed in assemblies with lesser slope than other single-plies and makes it tolerable to incidental ponding and deflection. Unlike built-up roofing, EPDM membrane does not contain organic material that can decay as the result of moisture caused by condensation or leaks. EPDM membrane, due to its ability to withstand extreme temperature, can be successfully used in assemblies with greater thermal resistance (thicker insulations with higher R-values). The ability of a roofing membrane to withstand temperature extremes is an important trait of a high performance material because temperature extremes could promote premature membrane aging and reduce the life expectancy of a roof.
EPDM membrane formulations have remained relatively constant for the past 40 years, with roof systems installed in the 1970s still performing well. Even so, EPDM manufacturers remain committed to continuous product innovations. In response to technological advancements, membrane research and contractor requests for more ergonomic products, EPDM accessory products continue to evolve in order to meet the demands of the industry.
Following over 15 years of off-market testing to verify performance, 90 mil EPDM membranes have recently been introduced into the market. This highly puncture resistant and tough membrane offers the thickest layer of monolithic waterproof protection in the roofing industry.
White EPDM combines the high-performance standards of traditional EPDM with a highly reflective, environmentally friendly surface designed to cut energy costs. In addition to the oils and the polymers used to make an EPDM membrane, another ingredient is added to the mix to enhance UV resistance. With white membrane titanium dioxide is typically used to reflect UV rays and prevent it from attacking the polymer. When used appropriately, usually in warm climates (including Tennessee), white EPDM can reduce air-conditioning costs without sacrificing durability of the roofing system. Because of its reflectivity, white EPDM is installed using mechanically attached or fully adhered systems. White EPDM does have it's drawbacks. Ask us if we recommend the white EPDM.