Before sustainability became a popular concept in building design, ballasted EPDM roof systems were widely used. Dating to the 1960s, this time-tested, reliable roof system still offers more sustainable features than many systems currently available.
What is ballasted EPDM?
A ballasted EPDM roof system has its components held in place by river-washed stones or pavers. Ballasted roofs are loose-laid, meaning roofing materials, including the insulation and roof membrane, are not fastened to one another or to the roof deck. Adjoining EPDM sheets are spliced together, and the membrane and insulation are held down with a minimum of 10 pounds of ballast per square foot. This system has been popular because of its low life cycle cost and quick, economical installation, which is one of the fastest and most cost-effective ways to achieve a weatherproof building envelope. When the system first was introduced, 45-mil-thick EPDM was common. More recently, there has been a trend to using more puncture-resistant 60-mil- and 90-mil-thick EPDM membranes.