EPDM System’s Long-Term Performance Reveals Important Lessons

For most of us, turning 40 is something of a milestone. Maybe a time for a party, some soul-searching and usually a lot of brave talk about how 40 is the new 30. Regardless, we have crossed into undeniable middle age.

When a roof turns 40, still healthy and well-functioning, that’s an accomplishment of a different sort, putting that roof out front in a league of its own. In October, 1980 — yes, 40 years ago — in West Bend, Wisconsin, a team of installers put the finishing touches on the first Firestone RubberGard EPDM roof. That 45-millimeter, 7,900 square feet of membrane is still protecting the headquarters of Albo Manufacturing today, and has continuously done so for the last 40 years. Kurt Mueller, now the president of Albo, was 22 when his dad decided to try out the new type of roofing membrane.

Why would someone agree to be the first in line to try out a new product, especially one that represented a major investment for a small independent job shop? “He was good buddies with the contractor,” Mueller says as he explains his dad’s decision. The contractor “gave my father his word that the roof would perform, and that, I believe, is what swayed my father.” For the contractor and his employees, the lure of installing the roof without having to use hot asphalt was also a plus.

The roof at the Albo job shop is a testament to the durability of EPDM. While results may vary, this 40-year old has withstood the extremes of the harsh Northern Wisconsin: tornadoes, thunderstorms with winds up to 60 miles per hour, almost two feet of snow, and temperatures that plunged to 20 degrees below zero in the winter and rose to a scorching 100 degrees plus in the summer.

Other than congratulating the owner for his savvy decision-making, why should we be talking about this durable roof? Is it a “one-off” or a sample of what might be expected from an EPDM membrane? Here’s why the 40-year performance of an EPDM roof is increasingly relevant today: we are facing new challenges now as we look for ways to protect our buildings from extreme weather events. While there may be debate about the cause, indisputable global statistics confirm the increasing frequency of more extreme weather: intense tornado outbreaks, record-setting heat, catastrophic wildfires, heavy downpours, longer droughts, and more frequent and more powerful hurricanes. This roof teaches us important lessons from its 40-year performance, and helps to inform decision-making moving forward.

In a highly competitive marketplace, the manufacturers of EPDM — Firestone Building Products as well as Carlisle SynTec Systems, and Johns Manville — have joined to create the EPDM Roofing Association (ERA), and invest in the science that delivers the data behind record-setting roofs like the facility in West Bend. This effort, in turn, has led to a generation of improvements that deliver a product based on 21st century science.

For instance, while ERA has numerous examples of the durability of EPDM from case studies, it was important to the association to investigate the science behind the longevity of their product. To that end, in a landmark aging study, ERA examined five roof systems with 28 to 32 years of in-field service, and concluded that all of the systems examined were still performing as intended. In fact, the study found that all of the samples were essentially performing “like new” with physical characteristic properties above or just below the minimum characteristics of newly manufactured 45-millimeter EPDM membrane. The roofs were first inspected in the field to get a good sense of their condition, and then samples were sent to a testing facility for the roofing industry. The laboratory testing examined five critical performance characteristics of the EPDM membrane.

The Elongation Test Results showed that four of the five roof samples exceeded the minimum characteristics for aged EPDM, and one exceeded the minimum for new EPDM. For Tensile Strength, all five samples exceeded the minimum standard. For Thickness XD (Cross Direction), three samples exceeded the manufacturer minimum, while the other two missed by one-thousandth of an inch. For Thickness MD (Machine Direction), three achieved or exceeded the minimum, while one missed by one one-thousandth of an inch and another by four one-thousandths of an inch. For Factory Seam Strength, it was only possible to test two of the samples, but both easily surpassed manufacturers’ minimums.

Overall, ERA has conducted four studies on EPDM that validate the long-term performance of the EPDM membrane. “The first field studies of EPDM were done in the late 1980s, and we are finding a pattern,” says Thomas W. Hutchinson AIA, FRCI, RRC and Principal, Hutchinson Design Group, Ltd., Barrington, Illinois. “The pattern is that these roofs can really last a long time. By using today’s advanced design techniques and proper roof maintenance, it is reasonable to expect that an EPDM roof will approach or exceed 40 years of service.”

Given the recent challenges of increasingly cataclysmic weather events, this durability and longevity is one important aspect of the contribution that EPDM can make to a resilient roofing system. Additionally, EPDM has excellent hail resistance, remaining flexible and pliable so that it can absorb the impact from hail without fracturing. The membrane is also very dimensionally stable when exposed to significant changes in temperature and EPDM is the only commercially available membrane that performs in an unreinforced state, making it very forgiving to large amounts of movement without damage and potentially more cycles before fatiguing. Seaming technology has constantly improved over the last 40 years, and has brought about innovations such as double-sided tape and factory applied tape. Sixty millimeter and 90-millimeter membrane has been introduced, offering enhanced puncture resistance.

These improvements to EPDM over the last four decades add up to increasingly sustainable and resilient construction. During a time when resilient structures are essential to a recovering economy, the value of updated EPDM is more evident than ever to the building owner. Kurt Mueller up in West Bend is grateful that his father’s roof continues to provide shelter for his small business. For anyone making a decision about a roofing membrane today, it’s important to know that the 21st century product, with increased strength and multiple improvements, is not your father’s EPDM.

For more information about EPDM as part of a resilient roofing system, consult ERA’s 2020 Resilience Report (http://epdmtheresilientroof.org.)