Long-term Performance of Roof Systems

The April e-newsletter distributed by Roofing contained an online exclusive about sustainability. The author, Brooks Gentleman, an owner of window refurbisher Re-View, Kansas City, Mo., questioned whether we’re talking about the right things when referring to a building as sustainable. He says, “During the past 10 years, there has been a great deal of talk about green buildings and sustainability, but how many of these ‘green’ commercial or residential buildings are designed or constructed to last for centuries? When will the life cycle of the structure and the construction materials themselves become factors in the sustainability criteria? It seems to me that more effort is placed on whether a material is recyclable than whether it can perform over the long haul. It is time that the design community, manufacturers and construction processes begin to consider the life of the building if we are truly going to incorporate sustainability in our industry.” (Read the entire article.)

Gentleman’s commentary is the perfect precursor to this issue, which has a focus on the long-term performance of a roof system. Three “Tech Point” articles explain the life spans of metal, EPDM and asphalt, respectively. The authors—Chuck Howard P.E., a Roofing editorial advisor; Thomas W. Hutchinson, AIA, CSI, FRCI, RRC, RRP, a Roofing editorial advisor; and James R. Kirby, AIA—share roof-cover characteristics that achieve and industry studies that prove long-term performance.

Insulation is a component that will help extend the life of a roof system. In “Cool Roofing”, Kyle Menard, president of Bloom Roofing, Brighton, Mich., shares insight about polyisocyanurate, specifically how it contributes to long-term roof performance and why the roofing industry should educate clients about its importance as part of a roof system.

As architects, building owners and occupants increase their expectations for the environmental performance of the buildings they design, operate and dwell in, building component manufacturers have begun rolling out environmental product declarations, or EPDs. EPDs are related to life-cycle assessments and product category rules, all of which are part of an ongoing effort to provide as much transparency as possible about what goes into the products that go in and on a building. In “Environmental Trends”, Allen Barry writes about the significance of EPDs for the roofing industry.

As a longtime proponent of sustainability, it’s wonderful to see the conversation turning toward the critical issue of durability and long-term performance. Yes, specifying materials with recycled content or from sustainably managed forests is a nice consideration, but if those materials will only last a few years and must be replaced, we’re expending more energy—and money—using them. There’s nothing sustainable about that.

Attach Almost Anything to Corrugated Profiles

CorruBracket 100T from S-5! is designed specifically for corrugated roofing profiles that are common in North America.

CorruBracket 100T from S-5! is designed specifically for corrugated roofing profiles that are common in North America.


CorruBracket 100T from S-5! is designed specifically for corrugated roofing profiles that are common in North America. CorruBracket 100T is affixed to the crest of the corrugation, leaving the drainage plane free of holes to protect against leaks. The bracket can be attached directly to the sheeting, accommodating ancillary attachment anywhere along the corrugation. For heavy-duty applications, the bracket can be fixed into the underlying substrate for additional support without crushing the corrugation. CorruBracket 100T comes with a factory-applied EPDM rubber gasket seal already on the base; the S-5!-patented reservoir conceals the EPDM from UV exposure.

Attach Almost Anything to Select Trapezoidal Roof Profiles

RibBracket from S-5! can be used to mount almost anything onto the most common exposed-fastened, trapezoidal roof profiles marketed in North America.

RibBracket from S-5! can be used to mount almost anything onto the most common exposed-fastened, trapezoidal roof profiles marketed in North America.


RibBracket from S-5! can be used to mount almost anything onto the most common exposed-fastened, trapezoidal roof profiles marketed in North America. The RibBracket comes with a factory-applied EPDM rubber gasket seal already on the base, and the S-5!-patented reservoir conceals the EPDM from UV exposure, preventing drying and cracks. The RibBracket is mounted directly onto the crown of the panel, straddling the profile. No surface preparation is necessary; simply wipe away excess oil and debris, align and apply. RibBracket is economical and facilitates quick and easy installation. The slotted top hole, which accommodates standard M8 nuts and bolts, simplifies alignment and maximizes flexibility in attaching ancillaries.

Install EPDM in Temperatures from 20 to 120 F

Firestone Building Products Co. LLC has launched its Secure Bond Technology, which ensures adhesion coverage across the entire roofing membrane.

Firestone Building Products Co. LLC has launched its Secure Bond Technology, which ensures adhesion coverage across the entire roofing membrane.


Firestone Building Products Co. LLC has launched its Secure Bond Technology, which ensures adhesion coverage across the entire roofing membrane. The company will offer Ultra Ply TPOSA and RubberGard EPDM SA with Secure Bond Technology. RubberGard EPDM SA and UltraPly TPO SA with Secure Bond Technology can be installed in temperatures between 20 and 120 F. The technology has no VOCs and does not emit odor during or after installation. It also is FM tested and approved, meets or exceeds all ASTM requirements and is covered by the Firestone Building Products Red Shield Warranty.

Wind-damaged Roof Systems

Wind damage to roof systems is often catastrophic, placing the building users at a life-safety risk, resulting in interior and furnishing damage and suspension of interior operations, loss of revenues, legal ramifications and great costs to repair. Because of my 30 years of experience in the design of roof systems and forensic investigation, I’m often called upon as an expert witness after wind events. In this article, I’ll review a couple wind-event roof failures, the causes of the failures and how they could have been prevented. I’ll also provide recommendations for failure prevention in the design process for new roof systems, as well as for existing roof systems.

1. The concrete roof deck panels deflected more than 3/4 inch, which the design architect should have accounted for if a thorough field investigation was undertaken.

1. The concrete roof deck panels deflected more than 3/4 inch, which the design architect should have accounted for if a thorough field investigation
was undertaken.

The Perfect Storm

How can it be that when roof systems are to be designed for code-required wind-uplift resistance that so many fail in winds well below the design parameters and/or warranty coverage? The answer could be design-related, material or installation; typically, it involves all three.

Architects and some roof system designers are often not as knowledgeable about roof systems as they should be, have little empirical evidence in how all the components work together as a system, and move beyond their abilities (a violation of their standard of care) when designing roofs where specific detailing is required. In addition, manufacturers are all too often
bringing new products to the marketplace that have not been properly vetted in the field and their long-term performance is truly unknown. Unfortunately, the roofing contractor cannot escape any of this. The lack of proper specification and contract document review; failure to review product data, including installation guidelines for new products; poor project oversight and management; and pressure from general contractors often result in installations that are subpar. The result is a “perfect storm” of design, materials and installation that fail under stress.

Consider the following case studies that I have been involved in as a forensic or “expert” witness when litigation was involved.

Coastal Facility

A large aged warehouse along the eastern seaboard was in need of a new roof system. Because the interior was not conditioned, thermal insulation was not required. The existing roof was an asphalt built-up with aggregate surfacing on high-density fiberboard on precast concrete panels 24-inches wide on a steel structure. The northern portion of the building had overhead doors that were seldom closed. On the interior, an aedicule structure (a building within a building) was constructed approximately 65-feet south of the overhead door, which had a ceiling level 5-feet below the roof deck.

2. The thin, flexible 1/2-inchthick high-density board was found to have little, if any, contact with the full-coverage spray-foam adhesive, making uplift extremely easy.

2. The thin, flexible 1/2-inch-thick high-density board was found to have little, if any, contact with the full-coverage spray-foam adhesive, making uplift extremely easy.

The architect who designed the replacement roof system called for the existing BUR roof to be removed down to the precast concrete roof panels. Then a new 1/2-inch 4- by 8-foot high-density wood fiberboard was set in full-coverage spray polyurethane foam adhesive with a 60-mil EPDM membrane fully adhered to the high-density wood fiberboard.

Additionally, the architectural drawings called for rooftop relief vents to be removed and capped over.

Around June 2008, a Nor’easter (an intense rainstorm), coming in from the east off the ocean, swept into the city. This resulted in the new roof system being lifted off the roof deck. Mode of failure was the fiberboard detaching from the precast concrete roof deck.

Investigation revealed several acts and conditions that contributed to the wind damage.

PHOTOS: Hutchinson Design Group Ltd.

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EPDM Can Meet FM 1-90 Ratings

Carlisle SynTec Systems has introduced its 6.5-foot Sure-Tough Reinforced EPDM

Carlisle SynTec Systems has introduced its 6.5-foot Sure-Tough Reinforced EPDM.

Carlisle SynTec Systems has introduced its 6.5-foot Sure-Tough Reinforced EPDM, ideal for projects requiring FM 1-90 ratings. When the 6.5-foot-wide sheets are used in conjunction with HP-XTRA fasteners and HPXTRA Polymer Seam Plates at 12 inches on center, the system qualifies for an FM 1-90 rating over a grade C steel deck. The maneuverability of the sheets makes them suitable for smaller, cut-up projects, and the packaging (two rolls per core) reduces roof loading time and minimizes construction waste on larger, wide-open projects. The EPDM features 6-inch Factory-Applied Tape, which delivers value by improving the speed and quality of EPDM seam applications.

Roofing Manufacturers and Contractors Embrace Recycling

In the early 2000s, as the green-building movement reached its tipping point, the roofing industry’s contributions to sustainability focused on increasing energy efficiency, improving long-term durability and addressing the heat-island effect. In the years since, significant strides have been made in all three of these areas for commercial and residential buildings.

In recent years, increasing attention has been given to the benefits and challenges of recycling roofing materials at the end of their useful life. This is no trivial task: Owens Corning estimates asphalt shingles alone comprise up to 5 percent of building-related landfill waste. This doesn’t take into account other roofing materials, including EPDM, thermoplastic PVC and metal.

Not surprisingly, rising removal costs, coupled with the growing demand in some areas of the country to legislate landfill content, are putting pressure on contractors and building owners to seek alternatives to traditional roof construction scrap and tear-off disposal methods.

In response, greater numbers of roofing manufacturers and contractors are driving strategies to avoid the landfill. A general review of emerging trends across the roofing industry suggests manufacturers and contractors increasingly are turning to recycling to steer these materials from the waste stream.

Steel is the most recycled material in building construction today. PHOTO: STEEL RECYCLING INSTITUTE

Steel is the most recycled material in building construction today. PHOTO: STEEL RECYCLING INSTITUTE

METAL

Metal roofing’s sustainable attributes are significant. Industry experts cite its ability to improve a building’s energy efficiency, and metal today contains anywhere from 25 to 95 percent recycled material.

On its website, the Chicago-based Metal Construction Association (MCA) encourages installing metal roofing directly over an existing roof, thus eliminating the need to dispose of the original materials. But when an older metal roof or new-construction debris must be removed from a site, contractors and owners in most regions of the country can quickly identify scrap yards that take metal.

“Steel is the most recycled material in building construction today,” says MCA Technical Director Scott Kriner. “There’s an infrastructure that supports it, and metal in general is virtually 100 percent recyclable.” Kriner notes MCA supports recycling as part of the metal industry’s overall commitment to environmental sustainability and transparency in business.

PVC

PVC has been used in roofing systems since the 1960s, and the post-consumer recycling of roof membranes began in North America in 1999—a nice symmetry when one considers roofs in terms of 30-year life cycles.

In general terms, the recycling of PVC roofing is a relatively straightforward process. The material is sliced into long strips, rolled up, lifted off the roof and transported to a recycling center. Recyclers run the PVC through a conveyor system, where fasteners and other metal objects are removed.

Initially, the recovered membrane was ground into powder for reuse in molded roof walkway pads. More recently, some manufacturers have been incorporating a granulated form into new PVC roofing membranes, exclusively on the backside to avoid aesthetic issues with color variations. The first installations of membrane produced with post-consumer recycled composition occurred in the mid-1990s. So far, its field performance has matched that of PVC roofing produced with virgin raw materials.

The Vinyl Institute, Alexandria, Va., says close to 1 billion pounds of vinyl are recycled at the postindustrial level yearly. “The vinyl industry has a history of supporting recycling,” the institute reports on its website, “and this effort continues as companies, alone and through their trade associations, expand existing programs and explore new opportunities to recover vinyl products at the end of their useful life.”

EPDM

Ethylene propylene diene terpolymer is used extensively on low-slope commercial buildings. Yet even this durable synthetic rubber membrane must eventually be replaced, and today recycling is a viable option.

The removal process generally involves power-vacuuming off the stone ballast, where present, to expose the EPDM membrane below. The membrane can then be cut into manageable squares, which are folded and stacked on pallets, loaded onto a truck and transported for recycling. The recycler grinds it into crumbs or powder, depending on the end use. A growing number of recycling centers nationwide now handles EPDM.

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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.