Elastomeric roofing based upon ethylene propylene diene terpolymer (EPDM) has been around for more than four decades and can claim 500,000 warranted roofs consisting of 20 billion square feet in place.
If one of these roof systems are on your buildings, you may not need a costly roof replacement just yet. Examine your roof to see if any of these EPDM fixes will work for you.
The Components of EPDM Roof Systems
Elastomers are defined as macromolecular materials that return rapidly to their approximate initial dimensions and shape after subsequent release of stress.
In contrast, thermoplastic materials will deform when stressed but not fully recover when the stress is removed. Thermoplastics include polymers such as polypropylene, polyvinyl chloride (PVC), chlorinated polyethylene, ketone ethylene ester (KEE) and chlorosulfonated polyethylene (Hypalon, which crosslinks upon weather exposure). Thermoplastic materials can be joined together (usually by heat welding), unlike elastomers, which cannot be heat welded.
EPDM combines two thermoplastics, ethylene and propylene, with a diene that permits the ethylene-propylene chains to be crosslinked. During vulcanization, this converts the properties of a roof membrane from a weldable thermoplastic to an inert, long-life, heat resistant elastomer.
During the early 1960s, these elastomeric properties were achieved through vulcanization of polymers such as natural rubber, butyl, neoprene, styrene butadiene rubber (SBR), chlorobutyl, polyepichlorohydrin, silicone, and other polymers. However, it has been demonstrated that only EPDM possessed the necessary combination of properties for long roof life and cost efficiency, confirmed by many roof systems that are still in service after 30 years or more.
As with the tires on our automobiles, carbon-black reinforced EPDM membranes have proven to have extraordinary weather, UV, and ozone resistance as well as enhanced physical properties. While white pigmented EPDM is available, indications are that the black material is, and will be, more resistant to UV attack over its long life.