What is it? How is it installed? How can it be maintained?
EPDM stands for ethylene, propylene diene monomer. EPDM roofing is a mixture of the EPDM polymer, carbon black pigment, oils and other additives. Besides roofing membranes, EPDM is used to make bicycle inner tubes, and radiator hoses.
EPDM roofing can be installed in one of three ways: ballasted, mechanically attached and fully adhered. Some jurisdictions will not allow ballasted installations, especially in high wind locations. Extensive damage was experienced in the hurricane that struck Houston several years ago because stone ballast blew off the roofs and broke windows, causing severe wind-blown rain damage.
Here's a coating opportunity: many building owners are demanding, and some jurisdictions require a "cool roof" or EPA Energy Star® listed reflective roof surface. Since EPDM roofs are black, they are obvious candidates for white reflective coatings to be applied to these new roofs. This creates an immediate opportunity for coating newly installed EPDM roofs.
EPDM roofs deteriorate by membrane erosion, shrinkage and seam failure. Since the seams are sealed with adhesives or tapes, they are not as strong as "welds", like the thermoplastic single plies discussed in previous issues. Shrinkage occurs when stone ballast on these roofs absorbs oils which are part of the EPDM roof membrane. The resulting shrinkage stresses seams and tears the membrane away from mechanically fastened termination bars.
EPDM roofing can be easily maintained. To achieve acceptable adhesion of a maintenance coating to the EPDM, some coating manufacturers require a pretreatment of a corrosive, very high pH "prerinse" or "rinseable primer" to be applied prior to applying the base coat. The effluent may be harmful to the environment and ground water. National Coatings Corporation has resolved this problem by eliminating the need for the corrosive rinseable primer. This reduces the installed cost, eliminating a time consuming and labor intensive step. The labor savings will add increased profits for the contractor.Besides the elimination of the need for the rinseable primer, National Coatings Corporation has developed a high performance primer, AcryShield A502, designed to give excellent adhesion to EPDM roofing. Specific details for these systems formatted as a three part CSI specification are found in the links below:
- Maintaining EPDM:
- Restoring EPDM: