Ballasted EPDM Roof Has Been in Service Since 1979

Rob Nelson is a 44-year-old software consultant who owns a multi-tenant, 137,000-square-foot building in Kingston, Pa. Rob’s dad bought the building in 1985, when it was an abandoned cigar factory and Rob took over management of it in 2002. He considers it to have been a good investment for many reasons. It has attracted a variety of tenants and currently houses about 25 businesses, including small, single-office enterprises, an engineering firm and a home-health nursing business. Rob’s family operates a furniture business and an indoor self-storage facility in the building, as well.

Roof Consultant Mark Sobeck inspects a 35-year-old ballasted EPDM roof on a multi-tenant building in Kingston, Pa.

Roof Consultant Mark Sobeck inspects a 35-year-old ballasted EPDM roof on a multi-tenant building in Kingston, Pa.

Besides its track record of attracting tenants, Rob also values his building for another very important reason: its ballasted EPDM roof has been in place since 1979. If you do the math, that’s 35 years. And Rob’s roofing consultant, Mark Sobeck, based in Wilkes-Barre, Pa., says he can realistically expect his building to get another 10 or 15 years of protection from the roof.

Rob and Mark emphasize that maintenance has been important to the roofing system as a whole. One-third of the original roof has been replaced for reasons not related to the membrane performance, and the flashing and expansion joints have been replaced on the original section of the roof. But the membrane itself, according to Sobeck, is still in great shape. “It’s amazing how the EPDM rubber is still lasting. At thirty-five years, it’s still stretchy and pliable and looks good.”

Nelson’s experience with the longevity of his roof is backed up by in-depth testing by the EPDM Roofing Association (ERA). ERA commissioned studies of five EPDM roofs that had been in use for between 28 and 32 years. The roofs, ballasted and fully-adhered, were first inspected in the field, and then small samples of the EPDM membrane were sent to Momentum Technologies, a testing facility for the roofing industry in Uniontown, Ohio. Five key performance characteristics of the samples were tested: elongation, tensile strength, cross-direction thickness, machine-direction thickness and factory-seam strength. The lab results showed that all the samples had physical characteristic properties above or just below the minimum physical characteristics of a newly manufactured 45-mil EPDM membrane. Put another way, after three decades of use, they were performing like new. Roofing experts point out that installation materials and methods have advanced considerably in the last 30 years, giving new roofing systems an expectation of an even longer service life.

A roof that lasts a long time will deliver obvious financial savings to building owners. In an era when environmental benefits must also be considered, experts say that its important to look at sustainability in the broadest possible terms. “If a roof lasts a very long time,” says John Geary, director of Education and Industry Relations for Firestone Building Products and chairman of the board of ERA, “that’s very good news for the environment. Compared to a roof that has to be replaced every 10 years or so, the choice of EPDM means fewer resources are ultimately used in the manufacturing and maintenance of the roofing system. Additionally, EPDM can be recycled, so it also means less materials winds up in a landfill.”

Rob Nelson may not have seen the results of EPDM lab tests, but he sees proof of the durability and longevity of EPDM every time he visits his building. “It’s pretty wild and definitely surprising that we are still kicking along after 35 years,” he says. Given consultant Mark Sobeck’s projections, Nelson can expect another 15 years or so of “wild” service from his EPDM roof.

ERA Challenges LBNL Study about White Roofs

The Bethesda, Md.-based EPDM Roofing Association (ERA) is challenging a study released by Lawrence Berkeley National Laboratory, Berkeley, Calif., which cites white roofs as the most “cost-effective” roofing option over a 50-year time span. The study, published in the March 2014 issue of Energy and Buildings, also calls for the phase-out of black roofs.

“Our members make both black and white roofing membranes. We strongly oppose any recommendation that irresponsibly promotes the use of one of our products over another based on faulty science. We question the validity of this study since it is based on a sample size of only 22 roofs, and we are challenging the conclusions that the authors draw from the data,” says Ellen Thorp, ERA’s associate executive director. “Due to the complexity of roof and building science, prescriptive requirements that limit design choices are not in the best interests of architects, design professionals or building owners.”

To help provide clarity regarding roofing-system choice and refute some errors in the study, ERA convened a panel of experts to review the LBNL science and its conclusions. A complete analysis can be found on the ERA website.

Overall, the LBNL study was marked by “a systematic failure to understand that roofs are systems, not a single component,” says Thomas W. Hutchinson, AIA, FRCI, RRC, principal of Hutchinson Design Group Ltd., Barrington, Ill., an internationally recognized expert on roof system design and a Roofing editorial advisor. “Additionally, the study completely ignored
ballasted EPDM systems that, in other studies, have proven to be the roof system that provides the greatest service life and energy savings. To suggest that a comparatively ‘new’ roofing material will have a longer service life than EPDM, a material proven to last over 30 years, is naïve.”

“Our members—Firestone Building Products, Carlisle SynTec Systems and Johns Manville—have a vested interest in providing accurate information to our customers,” Thorp adds. “Their knowledge is based on marketing, installing and maintaining thousands of roofing systems. We hope that architects, specifiers and roofing consultants will continue to rely on their field-based knowledge about the comparative costs and effectiveness of roofing systems, rather than on flawed science based on flimsy and biased data.”

Benjamin Mandel, a research assistant in the Heat Island Group at LBNL and an author of the LBNL study, recently responded to ERA’s remarks on Today’s Facility Manager’s website.
Read Mandel’s reaction at bit.ly/1hcD0HR.