After Years of Roof Leaks, a Laboratory That Produces Theatrical Equipment and Software Undergoes a Complex Reroofing

Founded in 1910, Rosco Laboratories is a multi-national producer of equipment, software and products for the theatrical, film, and television industries and architectural environment. As with every aging flat roofing system, water leakage was becoming a recurring problem at Rosco’s Stamford, Conn., facility. The severity of the leakage was further exacerbated by the lack of roof drainage (only two roof drains serviced the entire building) and poor deck slope conditions (less than 1/16 inch per foot).

The gypsum decking was cut out within the limits of the entire framing “bay” and infilled with galvanized metal decking. The longitudinal deck panel edge was seated atop the horizontal leg of the bulb-tee section (visible in the center of the photograph) and mechanically fastened using self-tapping screws. The ends were supported by the steel purlins. The underside of the decking was prepainted to match the ceiling finish. Supplemental structural support consisting of strips of 14-gauge galvanized sheet metal were attached to the bottom of each bulb-tee section contiguous to the repair to provide additional support for the adjacent gypsum roof decking segment.

The gypsum decking was cut out within the limits of the entire framing “bay” and infilled with galvanized metal decking. The longitudinal deck panel edge was seated atop the horizontal leg of the bulb-tee section (visible in the center of the photograph) and mechanically fastened using self-tapping screws. The ends were supported by the steel purlins. The underside of the decking was prepainted to match the ceiling finish. Supplemental structural support consisting of strips of 14-gauge galvanized sheet metal were attached to the bottom of each bulb-tee section contiguous to the repair to provide additional support for the adjacent gypsum roof decking segment.


Rosco representatives employed traditional methods to control and/or collect the moisture within the building by use of several water diverters. This technique was effective but Rosco representatives soon recognized this was not a viable long term solution as the physical integrity of the roof structure (deck) became a principal concern to the safety of the building occupants.

The Fisher Group LLC, an Oxford, Conn.-based building envelope consulting firm was retained by Rosco in March 2009 to survey the existing site conditions and determine the need for roofing replacement. The existing roofing construction, which consisted of a conventional two-ply, smooth-surfaced BUR with aluminized coating, exhibited numerous deficiencies (most notably severe alligatoring) and was deemed unserviceable. Construction documents, including drawings and specifications and a project phasing plan were developed by Fisher Group to address the planned roof replacement.

Bid proposals were solicited from prequalified contractors in June 2010, and F.J. Dahill Co. Inc., New Haven, Conn., was awarded the contract on the basis of lowest bid.

Existing Conditions

The building basically consists of a 1-story steel-framed structure constructed in the 1970s. It is a simple “box”-style configuration, which is conducive to manufacturing.

In conjunction with design services, destructive test cuts were made by Fisher Group in several roof sections as necessary to verify the existing roofing composition, insulation substrate, moisture entrapment, and substrate/deck construction. A total of four distinct “layers” of roofing were encountered at each test cut. The existing roofing construction consisted of alternating layers of smooth- and gravel-surfaced, multi-ply felt and bitumen built-up roofing. The bitumen contained throughout the construction was fortunately asphalt-based. Succeeding layers of roofing were spot mopped or fully mopped to the preceding layer (system). The combined weight of the roofing construction was estimated to be upwards of 20 to 22 pounds per square foot when considering the moisture content. This is excessive weight.

The roof insulation panels were set into ribbons of low-rise polyurethane foam insulation adhesive. The adhesive was applied in a continuous serpentine bead, spaced 6 inches on-center throughout the field of the roof.

The roof insulation panels were set into ribbons of low-rise polyurethane foam insulation adhesive. The adhesive was applied in a continuous serpentine bead, spaced 6 inches on-center throughout the field of the roof.


It is interesting to note that a minimal amount of roof insulation was present in the existing construction. Insulation was limited to a single layer of 1/2-inch-thick fiberboard. Additional insulation would need to be provided as part of the replacement roofing construction to increase the roof’s thermal performance and comply with the prescriptive requirements of the Connecticut State Energy Conservation Construction Code.

The structural substrate, or decking, is conventional in nature, comprised of poured gypsum roof decking. The roof decking incorporates 1/2-inch gypsum formboard loose laid between steel bulb-tee supports spaced about 32 inches on-center. The poured gypsum roof decking in this instance was utilized as the structural substrate and for insulating purposes. Poured gypsum roof decking has a minimal insulating value of perhaps R-2 to R-3, which is obviously considered to be minimal by present standards.

A representative number of bulk material samples were obtained by Fisher Group from the existing roofing construction as necessary to determine the material composition. The sampling included field membrane roofing plies, coatings and cements, and associated roof penetration and perimeter flashings. Laboratory analysis revealed that the second, third and, in some instances, fourth roofing “layers” (field membrane plies) contained varying amounts—5 to 10 percent—of asbestos (chrysotile) which would necessitate full abatement of the roofing construction.

PHOTOS: The Fisher Group LLC

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You Can Influence Codes and Standards

As associate executive director of the Washington, D.C.-based EPDM Roofing Association (ERA), I focus a great deal of my time and energy on the codes and standards that regulate or guide the roofing business. In the current environment, driven by constant upgrades in technology, as well as the need to save energy, these codes—and the standards that often inform them—seem to be undergoing steady revision. Believe it or not—and the word “geek” does come to mind—I find participating in this process extremely interesting. In fact, following and sometimes influencing emerging codes and standards is among the most important responsibilities of my job.

I’ll be the first to admit that a detailed review of a standards manual is probably not anyone’s idea of exciting reading. But given the importance of codes and standards to the construction industry, we ignore them at our own risk.

For a start, what’s the difference between a code and a standard? Ask enough people in the roofing industry and you will get a variety of answers. But generally, codes are the “top-tier” documents, providing a set of rules that specify the minimum acceptable level of safety for manufactured, fabricated or constructed objects. They frequently have been enacted into local laws or ordinances and noncompliance can result in legal action. Standards, on the other hand, establish engineering or technical requirements for products, practices, methods or operations. They literally provide the nuts and bolts of meeting code requirements. If codes tell you what you have to do, standards tell you how to do it. Frequently, standards—especially “voluntary consensus standards”—are the precursors for what becomes law years down the road.

ERA has represented the manufacturers of EPDM roofing for more than a decade. Through the years, we have learned the importance of interfacing with standard-setting and regulatory bodies. One of our first, and most important, learning experiences was working with the Northeast and mid-Atlantic states when they issued regulations designed to achieve federally mandated air-quality standards. (See the article in Roofing’s September/October 2014 issue, page 58.) The initial regulations, which lowered the amount of VOCs in many roofing products, were based on those used in southern California and incorporated provisions that were effective in the climactic and market conditions of that state. But states in the affected areas, from Virginia to Maine, confronted a situation where the new regulations threatened to bring the roofing industry to a sudden halt. In some instances, no adhesives and sealants were available to meet the new standards. And the new products, when they became available, would need to be effective in very cold climates totally unlike those on the West Coast.

ERA worked with officials throughout the impacted areas, helping to create “phase-in” schedules that would give industry enough time to develop products to meet the new standards. In state after state, the local regulators welcomed our input. Our point-of-view was based on a deep understanding of the business needs of our industry. Just as important, we understood the science behind the proposed regulations and could work with the regulatory bodies to ensure the air-quality needs and the needs of the roofing industry were met.

This experience has informed our ongoing approach to code-setting and regulatory bodies. Since our work with the states setting VOC standards, we have invested staff time and resources to stay current with and even ahead of proposals that would impact our members and their customers. We have testified before the South Coast Air Quality Management District in California on its proposal to limit VOCs. ERA has organized an ad-hoc coalition to successfully oppose an unnecessarily stringent proposal to require reflective roofs in the Denver area. And our organization is currently providing input to Atlanta-based ASHRAE’s efforts to clarify its regulation regarding air leakage. This issue—of great importance to the roofing industry—relates to other work being done in ASHRAE working groups and subcommittees on thermal bridging, as well as the definition of walls and wall assemblies. ASHRAE has convened an “Air Leakage Work Group” whose charge is to review the pertinent sections of Standard 90.1 and make recommendations for revising it. ERA staff will be present at this group’s meetings and will once again provide input based on the expertise of our members.

When I work with code-setting and regulatory groups, I am reminded of that very familiar saying, “It’s not whether you win or lose, it’s how you play the game.” Based on our work at ERA, I’d like to revise that. Your skill at “playing the game” will definitely influence whether you win or lose. Our experience tells us that staying involved with regulatory groups and providing them with input based on firm science and field experience leads to a winning outcome for the roofing business.

Firestone Building Products Celebrates 35 Years of Its EPDM Roofing System

Firestone Building Products Co. LLC, a manufacturer and supplier of a comprehensive “Roots to Rooftops” product portfolio, is celebrating the 35th anniversary of its trademark ethylene propylene diene monomer, RubberGard EPDM roofing system, which has helped cement its commercial roofing reputation for trust and confidence.

Firestone Building Products began its journey to become a global leader in the commercial roofing industry in 1980 with the installation of its first warranted EPDM roof in the small town of West Bend, Wis.

“At the beginning, none of us really knew the life expectancy of the EPDM roof,” says Clay Van Gomple, president of Spec Products, a sales representative for Firestone Building Products. “The Firestone Building Products professionals were very positive they had the formulation.”

Today, Firestone Building Products is internationally known to set the standard for quality rubber products, innovation and leadership. Its manufacturing plant opened in Prescott, Ark., in 1983 and has increased capacity to become the largest EPDM manufacturing facility in the world. Since 1980, approximately 6.5 billion square feet of Firestone Building Products RubberGard EPDM have been installed globally.

Throughout the years, Firestone Building Products has grown from one to 15 plants and expanded into multiple product lines, including EPDM rubber membranes, thermoplastic membranes, modified bitumen and polyisocyanurate insulation.

“Innovating new commercial building performance solutions is top of mind at Firestone Building Products because we understand and always consider the unique challenges of our contractors, architects and building owners,” says Tim Dunn, president of Firestone Building Products. “This 35th anniversary milestone demonstrates our commitment to those key stakeholders. Their trust is the reason we can confidently promise that, ‘Nobody Covers You Better.'”

The original EPDM formulation has held strong for more than three decades and still holds strong today. Firestone Building Products has built on that foundation of reliability, evolving its application to meet the needs of building owners, contractors and architects.

In 2015, Firestone Building Products introduced its revolutionary Secure Bond Technology, the next generation in fully adhered roof system application. Secure Bond Technology ensures adhesion coverage across the entire roofing membrane, establishing one of the most powerful bonds possible. RubberGard EPDM SA with Secure Bond Technology is the only EPDM SA available on the market today.

Firestone Building Products Announces Master Contractor Award Winners

Firestone Building Products Co. LLC, a manufacturer and supplier of a comprehensive “Roots to Rooftops” product portfolio, announced the 263 firms that earned the 2016 Master Contractor Award. The top-tier companies were selected from a network of more than 3,000 Firestone Building Products Red Shield Licensed Roofing Contractors for delivering exemplary installation, quality of work and customer service.

The Master Contractor Program presents three distinct industry honors annually: The Master Contractor Award, Inner Circle of Quality Award and President’s Club Award. The program’s 2016 winners collectively installed more than 309 million square feet of warranted Firestone Building Products roofing systems on new and reroof projects during 2015.

“Our annual Firestone Building Products Master Contractor Program recognizes top-tier firms for their commitment to excellence and superior workmanship,” says Tim Dunn, president of Firestone Building Products. “Ultimately, the winners’ attention to detail during all installation phases helps ensure long-term roofing system performance. Master Contractor, Inner Circle of Quality and President’s Club award winners represent our best partners in the industry. We are proud of all they have accomplished and look forward to continuing to see them achieve.”

The program’s 2016 award categories and parameters include:

  • Master Contractor
    Master Contractor Award recipients were selected based on the total square footage installed and quality points accumulated for outstanding inspection ratings on systems covered by the Firestone Building Products Red Shield Warranty. Those include: RubberGard EPDM, UltraPly TPO, asphalt and metal roofing systems.

    Master Contractors were also eligible to earn points in the sustainability category. The program recognizes Firestone Building Products’ SkyScape Vegetative Roof System and SunWave Daylighting System.

    To meet the 2016 award requirements, a contractor had to complete a minimum of eight Red Shield warranted jobs during the 2015 calendar year, be in good financial standing with Firestone Building Products, and have a Preferred Quality Incidence Rating (QIR) that did not exceed three times the average QIR for Red Shield Licensed Roofing Contractors. QIR is determined by the annual number of quality incidents per million square feet of roofing under warranty.

  • Inner Circle of Quality
    Master Contractors were eligible for the Inner Circle of Quality Award by installing a minimum of eight warranted Firestone Building Products roofing systems each in 2014 and 2015; and four roofs per year for each of the prior three years. They were also required to maintain at least 2 million square feet of Firestone Building Products roofs under warranty and achieve an annual Quality Incidence Rating (QIR) of 1.0 or less.

  • President’s Club
    Master Contractors who have accrued the highest number of quality points for superior inspection ratings and total square footage of Firestone Building Products Red Shield warranted roofing system installations completed during the past year earned the distinguished President’s Club Award.

Johns Manville Plans to Build Second Production Line at Its Alabama Manufacturing Facility

Johns Manville (JM), a global building and specialty products manufacturer and a Berkshire Hathaway company, announced plans to build a second production line at the company’s Scottsboro, Ala., manufacturing facility. The new line will increase production capacity for JM TPO (thermoplastic polyolefin).

“This significant investment continues JM’s long-standing commitment to our customers, the industry, our employees and the communities in which we serve,” says Mary Rhinehart, JM’s president and CEO.

State and local officials in Alabama welcomed the announcement. “Alabama workers make all kinds of great products, and I am honored that Johns Manville has decided to expand its plant in Scottsboro with new capital investment that means more jobs for Alabama residents,” Gov. Robert Bentley says. “Creating jobs and opportunity in the state is my No. 1 priority, and we are committed to helping Johns Manville achieve success with this project in Jackson County.”

“JM has been an important member of our community for eight years,” says Scottsboro Mayor Melton Potter. “Their recent capacity expansion and the announcement of adding a second line shows JM’s confidence in our workforce to produce the best TPO in the industry. I thank JM for choosing to make this investment in Scottsboro and Jackson County.”

In October 2008, JM’s commitment to single ply manufacturing was solidified with the opening of a state-of-the-art TPO facility in Scottsboro. JM furthered its investment in single ply in 2012 with the opening of an EPDM (ethylene propylene diene monomer) manufacturing plant in Milan, Ohio.

The new TPO production line will bring JM’s total investment in commercial roofing over the past eight years to approximately $200 million. Together with putting money back in the American economy and bringing more than 175 jobs to the manufacturing sector, JM’s continued investments allow growth in the industry and extend JM’s areas of roofing expertise and available products.
To meet recent demand for JM TPO, JM began a capacity expansion project in March 2015 at the Scottsboro plant. Construction was completed in May, and now work will begin to construct the second production line.

“The plant expansion was a huge success and made our Scottsboro facility what is, in our view, the most productive and efficient TPO facility in the U.S., enabling us to meet our customers’ needs for the foreseeable future,” says Jennifer Ford-Smith, JM’s director of Marketing and Single Ply. “This new line will give JM the ability to supply our customers with even more JM TPO than was previously available.”

Senior vice president and general manager Robert Wamboldt says, “We’re proud to be a part of the commercial roofing industry, and we believe our 157-year history demonstrates that we are here to stay. This new production line will help JM meet customer demand and remain a supplier of choice in our industry.”

Creating Visual Impact with Copper and Silver Roofing Membranes

Whether you’re re-roofing a historic building that needs to maintain its aesthetics or you’re working on a new roof construction that has to make a statement, there are many instances in which a building owner would want his or her roof to generate a specific architectural appeal. The most difficult part of this is balancing durability and beauty with cost. Roof systems today have evolved to solve this conundrum. Now, copper and silver synthetic PVC membranes are being used to achieve the desired appearance of a metal standing-seam roof at a fraction of the cost without sacrificing performance.

Alternatives to Metal Roof Systems

Michigan State University replaced the existing slate roof system with SOPREMA SENTINEL Copper Art to provide the desired appearance and required long-term performance.

Michigan State University replaced the existing slate roof system with SOPREMA SENTINEL Copper Art to provide the desired appearance and required long-term performance.


Copper and silver synthetic membranes are great cost-effective alternatives to metal roofs. As flexible synthetic systems, these roof membranes are economical and easy to install by conforming to complex geometries.

Certain synthetic PVC roof membranes on the market today are offered in a variety of colors, some of which can mimic the look of metal roofing. While these roof membranes offer the proven long-term performance of flexible polyvinyl chloride (PVC), they provide the metal appearance via the addition of pigments that can chalk or fade as the pigmented membrane ages, therefore losing the desired aesthetic feature.

Conversely, SOPREMA SENTINEL Copper and Silver Art PVC membranes incorporate copper or aluminum metallic powder into the PVC formulation, producing an enhanced metallic look. Unlike pigmented membranes, SENTINEL Copper Art provides the same weathering capabilities as traditional standing seam copper—the SENTINEL Copper Art will patina as a traditional copper roof would. Silver Art is unique because the color will not fade due to the addition of metallic powder, and its surface layer is factory embedded with an acrylic shield treatment to resist dirt pickup and chalking. Copper Art and Silver Art membranes provide the long-lasting aesthetic appearance and waterproofing abilities of a metal roof.

Applications for Copper and Silver Membranes

Copper and silver roof membranes are often used on buildings where aesthetics are important. Historic buildings, churches, schools, government buildings and army bases are a few examples of where this type of roof membrane has been installed. These buildings may require a particular appearance or designers may simply wish to update the appearance or provide some panache. Mansards or other areas of visible existing light-gauge metal roof systems may be present on these buildings and flexible copper and silver roof membranes may be used as an alternative aesthetic solution.

SENTINEL Silver Art met Glenside Public Library’s leak-free and architectural needs, plus the roofing contractor liked that the SENTINEL membrane was easy to install and looked great upon completion.

SENTINEL Silver Art met Glenside Public Library’s leak-free and architectural needs, plus the roofing contractor liked that the SENTINEL membrane was easy to install and looked great upon completion.

For example, since 2007, the slate roof of the Snyder-Phillips residence hall at Michigan State University had been leaking. The university needed to replace the existing slate roofing system with a new system that would meet the aesthetic requirements of the historic building. SOPREMA SENTINEL Copper Art was installed as a cap sheet to provide the desired appearance and the required long-term performance.

In addition, the Glenside Public Library had an existing standing-seam roof that was tied-in to a low-slope ethylene propylene diene monomer (EPDM) roof. The tie-in between the two materials was problematic and continuously leaked. The library wanted to preserve the standing-seam appearance, but the noise created by wind and rain on the metal roof was a concern.

SOPREMA SENTINEL Silver Art was selected because it could provide the desired look while eliminating the tie-in issues between the steep- and low-slope roofing materials. SENTINEL Silver Art met the library’s leak-free and architectural needs, plus the roofing contractor liked that the SENTINEL membrane was easy to install and looked great upon completion. In addition to its aesthetic appeal, SENTINEL Silver Art also offered the benefit of significant noise reduction when compared to the former metal roof system.

Roofing Technology Advancements

As roofing technology advances, the options for creating a desired aesthetic have evolved. SENTINEL PVC Copper and Silver Art are high-performance roof membranes that provide the appearance of metal with the flexible, long-term performance of PVC, without the weight, expense or complexity of a traditional metal roof.

With Today’s ‘New Age’ Roofs, Removing All System Components May Not Always Be Required or in the Clients’ Best Interest

Years ago, reroofing design involved removing all roof-system components down to the roof deck and rebuilding a new roof system up from there.

PHOTO 1: This EPDM roof’s service has been extended for nine years and counting, approaching 30 years in-situ performance. Here, the restoration of perimeter gravel- stop flashing and lap seams, as well as detailing of roof drains, penetrations and roof curbs, is nearing completion.

PHOTO 1: This EPDM roof’s service has been extended for nine years and counting, approaching 30 years in-situ performance. Here, the restoration of perimeter gravel- stop flashing and lap seams, as well as detailing of roof drains, penetrations and roof curbs, is nearing completion.

Although that is still a viable option and often performed, the coming of age of many single-membrane roofs has altered the method of installing a new reroof system. Options now include EPDM roof restoration; removal of the roof membrane and the addition of new insulation and roof membrane; using the existing roof membrane as a vapor retarder and adding new insulation and roof membrane; removal of the roof cover and installation of new, leaving all the existing insulation in place.

When I first moved into roof-system replacement design some 35 years ago, the dominant roof systems being removed were bituminous, specifically gravel-surfaced asphaltic and coal- tar-pitch built-up roofs. As they aged, their surfaces often started to blister, crack and undulate with ridges—surfaces often unsuitable for roof recover. The bitumen often was deteriorating because of ultraviolet-light exposure; when that occurred, the deterioration of the felts was not far behind. The insulation was mostly perlite or high-density wood fiber; the amount was minimal (low thermal value) and, more often than not, flat or with very minimal slope. Drains were erratically placed, tapered insulation was not often the case and roof edges were predominately gravel stops. In the Midwest, many roof decks were cementitious wood fiber. The roof covers were often patched again and again, even as water infiltrated the system.

PHOTO 2: The re-flashing of roof curbs is an integral part of the restoration of EPDM roof membranes.

PHOTO 2: The re-flashing of roof curbs is an integral part of the restoration of EPDM roof membranes.

When replacement was necessary, the roof-edge sheet metal was removed; the entire existing roof system was removed down to the roof deck; and a new roof system was designed, often incorporating vapor retarders/temporary roofs so the removal of multiple layers of roofing could be accomplished, roof curbs raised, and enhancements of roof drains, curbs and roof edge could occur prior to the installation of the new roof cover. Tapered insulation designs be- came common; this would often require realignment of the roof drains to simplify the tapered design and installation. To accommodate the new insulation thickness, the roof edge had to be raised as did roof curbs, RTU curbs, plumbing vents and roof drains via extensions. Roof membranes changed from bituminous to those classified as “single plies”: EPDM, PVC, CPE, CSPE.

These new roof-system replacement designs resulted in superior roofs—85 percent of all the reroofs I have designed are still in place, still performing, still saving the owner money. Life cycles have moved from eight to 12 years, up to 18 to 25 years and longer. They certainly were more expensive than the original installation and, if a roof designer didn’t have a handle on costs to provide the owner with estimated costs of construction, were often shocking. But these roof systems were good for the client, economy, environment and public.

PHOTO 3: When restoring EPDM roof membranes, the removal of roof penetration flashings and installation of new with target patches will provide another 20 years of watertight protection.

PHOTO 3: When restoring EPDM roof membranes, the removal of roof penetration flashings and installation of new with target patches will provide another 20 years of watertight protection.

Over the years, codes and standards have changed, especially in the past decade, requiring increased insulation values and roof-edge sheet-metal compliance with greater attention to wind-uplift resistance. As the new millennium arrived, these “new age” roofs came of age and owners started to look at their replacement—often with increased costs stifling their budgets.

LEAN THINKING

A factor that increased the performance of many roof systems in the past 20 years was the emergence and growth of the professional roof consultant, often degreed in architecture or engineering, educated in roofing, tested and certified. These professionals brought a scientific approach to roof-system design. Raleigh, N.C.-based RCI Inc. (formerly Roof Consultants Institute) was the conduit for this increased level of knowledge, professionalism and the growth in quality roof-system design and installation.

PHOTO 4: On this roof, the existing loose-laid membrane was removed, open insulation joints filled with spray-foam insulation and new insulation added to meet current code requirements. A new 90-mil EPDM membrane was installed and existing ballast moved onto it to 10-pounds-per-square-foot coverage.

PHOTO 4: On this roof, the existing loose-laid membrane was removed, open insulation joints filled with spray-foam insulation and new insulation added to meet current code requirements. A new 90-mil EPDM membrane was installed and existing ballast moved onto it to 10-pounds-per-square-foot coverage.

As these professionals started to examine the older “new age” roofs, those whose first responsibility was doing what was best for the client saw greater opportunity than just a costly full-roof replacement. Although many roofs today still need to be fully removed, prudent professionals see other opportunities, such as the following:

ROOF RESTORATION
EPDM membrane ages with little change in physical characteristics as opposed to its built-up roofing predecessor; therefore, EPDM membranes often can be “restored” in lieu of removing and replacing the roof. (Studies to support the lack of change in EPDM’s physical characteristics while it ages include Gish, 1992; Trial, 2004; and ERA, 2010.)

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Black EPDM Roofing Helps Multifamily Buildings Achieve the Passive House Standard

Two years ago, the three low-rise apartment buildings at the intersection of Southern Avenue and Benning Road in Washington, D.C., stood derelict and abandoned, uninhabitable reminders of 1960s brick and block construction. Today, the buildings—now known as Weinberg Commons—represent a landmark effort to provide clean, secure and energy-efficient shelter to low-income families. For the scores of people—architects, energy consultants, contractors and experts in housing finance, to name a few—who helped repurpose Weinberg Commons and bring it back to life, this project represents an unparalleled achievement in retrofitting. For the families who now live here, it means a giant step toward a more secure future.

Thermal conductivity, air infiltration and exfiltration, and solar gain were important to the team working on Weinberg Commons

Thermal conductivity, air infiltration and exfiltration, and solar gain were important to the team working on Weinberg Commons.

One of the keys to that secure future will be very low or no energy bills. From the beginning, the team that oversaw the retrofitting of these buildings, each with almost 8,000 square feet of rentable space, was committed to ensuring that all three would show greatly reduced energy use and at least one would achieve Passive House (PH) certification.

The criteria to become a passive structure are rigorous and focus on three specific design elements to reduce energy. (The requirements and certification observed by the Weinberg Commons team are set by Chicago-based PHIUS, the Passive House Institute U.S.)

The first requirement is airtightness to ensure the building minimizes the amount of heated or cooled air it loses (0.6 air changes per hour at 50 Pascals of pressure).

Second, a Passive House cannot use more than 4.75 kBtu per square foot per year. This is specific heating energy demand (or cooling in cooling climates).

The third requirement caps the peak total amount of energy the heating and cooling system and appliances in the building can use per year, including domestic hot water, lighting and plug loads. It cannot exceed 38 kBtu per square foot per year.

three low-rise apartment buildings at the intersection of Southern Avenue and Benning Road in Washington, D.C., stood derelict and abandoned, uninhabitable reminders of 1960s brick and block construction.

Three low-rise apartment buildings at the intersection of Southern Avenue and Benning Road in Washington, D.C., stood derelict and abandoned, uninhabitable reminders of 1960s brick and block construction.

Michael Hindle, a Baltimore-based Certified Passive House Consultant who is current president of the Passive House Alliance U.S. Board of Managers, helped with the retrofit design of Weinberg Commons. (Passive House Alliance U.S. is a PHIUS program designed to advance passive building.) He points out these three pass/fail criteria are measures of success, not design principles to help a team achieve the energy savings that lead to PH certification. However, Hindle highlights five design principles have been identified as important guides in the design of Passive House projects:

  • Continuous insulation through the building’s entire envelope without any thermal bridging.
  • An extremely tight building envelope, preventing infiltration of outside air and loss of conditioned air.
  • High-performance windows and doors, typically triple-paned.
  • Balanced heat- and moisture-recovery ventilation and a minimal space-conditioning system.
  • Solar gain is optimized to exploit the sun’s energy for heating purposes and minimize it in cooling seasons.

Although only one building at Weinberg Commons has achieved PH certification, all three buildings were designed to the exact same specifications and technically could be PH certified as long as the rigorous airtightness threshold is met. Several factors influenced the decision, made at the outset of the project, to focus on just one building for PH certification. The design team’s perception was that airtightness would be the most challenging aspect for the contractor. Matt Fine, an architect with Zavos Architecture & Design, Frederick, Md., who led the project, explains: “The intention was to proceed with the first building, test its airtightness and improve on that scope of work for the next building. Repeat, refine and finally apply to the third sequential building.”

Fine points out the first two buildings actually achieved “super” airtightness results relative to any new-construction project built today but did not cross the 0.6 air changes per hour at 50 Pascals of pressure threshold of Passive House. Given the budget-conscious nature of the Weinberg Commons project, resealing and retesting of the first two buildings was not an option for the team, but lessons learned from these two buildings were applied to the retrofit of the third building. “In retrospect, all three buildings would have been able to meet the PH threshold with relatively little extra effort,” Fine says. “But the dynamics of construction sequencing, along with imposed schedules for occupancy, complicated our ability to be flexible with scope change once the contracts were executed and limited dollars were allocated.”

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The Roof Cover: The Cap on the Roof System

For nearly two years in this magazine, I have been discussing the various components that make up a roof system: roof deck, substrate boards, vapor/air retarder, insulation and cover boards (see “More from Hutch”, page 3). Although each component delivers its own unique benefit to the system, they are intended to work together. When designing a roofing system, components cannot be evaluated solely on their own and consideration must be taken for a holistic view of the system; all components must work together synergistically for sustainable performance. Unfortunately, I often have seen that when components are not designed to work within the system unintended consequences occur, such as a premature roof system failure. A roof system’s strength is only as good as its weakest link. The roof cover is the last component in the design of a durable, sustainable roof system—defined previously as being of long-term performance, which is the essence of sustainability.

This ballasted 90-mil EPDM roof was designed for 50 years of service life. All the roof-system components were designed to complement each other. The author has designed numerous ballasted EPDM roofs that are still in place providing service.

PHOTO 1: This ballasted 90-mil EPDM roof was designed for 50 years of service life. All the roof-system components
were designed to complement each other. The author has designed numerous ballasted EPDM roofs that are still in place providing service.

The roof cover for this article is defined as the waterproofing membrane outboard of the roof deck and all other roof-system components. It protects the system components from the effects of climate, rooftop use, foot traffic, bird and insect infestation, and animal husbandry. Without it, there is no roof, no protection and no safety. When mankind moved from cave dwellings to the open, the first thing early humans learned to construct was basic roof-cover protection. Thus, roof covers have been in existence since man’s earliest built environment.

WHAT CONSTITUTES AN APPROPRIATE ROOF COVER?

There is no one roof cover that is appropriate for all conditions and climates. It cannot be codified or prescribed, as many are trying to do, and cannot be randomly selected. I, and numerous other consultants, earn a good living investigating roof failures that result from inappropriate roof-cover and system component selection.

There are several criteria for roof-cover selection, such as:

  • Compatibility with selected adhesives and the substrate below.
  • Climate and geographic factors: seacoast, open plains, hills, mountains, snow, ice, hail, rainfall intensity, as well as micro-climates.
  • Compatibility with the effluent coming out of rooftop exhausts.
  • Local building-code requirements, such as R-value, fire and wind requirements.
  • Local contractors knowledgeable and experienced in its installation.
  • Roof use: Will it be just a roof or have some other use, such as supporting daily foot traffic to examine ammonia lines or have fork lifts driven over it?
  • Building geometry: Can the selected roof cover be installed with success or does the building’s configuration work against you?
  • Building occupancy, relative humidity, interior temperature management, building envelope system, interior building pressure management.
  • Building structural systems that support the enclosure.
  • Interfaces with the adjacent building systems.
  • Environmental, energy conservation and related local code/jurisdictional factors.
  • Delivering on the expectations of the building owner: Is it a LEED building? Does he/she want to go above and beyond roof insulation thermal-value requirements to achieve even better energy savings? Is he/she going to sell the building in the near future?

ROOF-COVER TYPES

There are many types of roof-cover options for the designer. Wood, stone, asphalt, tile, metal, reed, thatch, skins, mud and concrete are all roof covers used around the world in steep-slope applications. This article will examine the low-slope materials.

The dominant roof covers in the low-slope roof market are:

    Thermoset: EPDM

  • Roof sheets joined via tape and adhesive
  • Installed: mechanically fastened, fully adhered or ballasted
  • Thermoplastic: TPO or PVC

  • Roof sheets joined via heat welding
  • Installed: mechanically fastened, fully adhered or plate-bonded (often referred to as the “RhinoBond System”)
  • Asphaltic: modified bitumen

  • Installed in hot asphalt, cold adhesive or torch application
  • EPDM (ETHYLENE PROPYLENE DIENE MONOMER)

    Fully adhered EPDM on this high school in the Chicago suburbs is placed over a cover board, which provides a high degree of protection from hail and foot traffic.

    PHOTO 2: Fully adhered EPDM on this high school in the Chicago suburbs is placed over a cover board, which provides a high degree of protection from hail and foot traffic.


    EPDM is produced in three thicknesses— 45, 60 and 90 mil—with and without reinforcing. It can be procured with a fleece backing in traditional black or with a white laminate on top. The lap seams are typically bonded with seam tape and primer.

    EPDM has a 40-year history of performance; I have 30-year-old EPDM roof systems that I have designed that are still in place and still performing. Available in large sheets—up to 50-feet wide and 200-feet long—with factory-applied seam tape, installation can be very efficient. Fleece-back membrane and 90-mil product have superior hail and puncture resistance. Historical concerns with EPDM lap-seam failure revolved around liquid- applied splice adhesive; with seam tape technology this concern is virtually moot. Non-reinforced ballasted and mechanically fastened EPDM roof membrane can be recycled.

    EPDM can be installed as a ballasted, mechanically fastened or fully adhered system (see photos 1, 2 and 3). In my opinion, ballasted systems offer the greatest sustainability and energy-conservation potential. The majority of systems being installed today are fully adhered. Ballast lost its popularity when wind codes raised the concern of ballast coming off the roof in high-wind events. However, Clinton, Ohio-based RICOWI has observed through inspection that ballasted roofs performed well even in hurricane-prone locations when properly designed (see ANSI-SPRI RP4).

    PHOTOS: HUTCHINSON DESIGN GROUP LTD

    Pages: 1 2 3

Coating Extends the Life of Aging Roofs

The new Silicone Roof Coating System from Mule-Hide Products Co. Inc. can be used to restore and repair asphalt, modified bitumen, metal, concrete, TPO, PVC and EPDM roof systems.

The new Silicone Roof Coating System from Mule-Hide Products Co. Inc. can be used to restore and repair asphalt, modified bitumen, metal, concrete, TPO, PVC and EPDM roof systems.

The new Silicone Roof Coating System from Mule-Hide Products Co. Inc. can be used to restore and repair asphalt, modified bitumen, metal, concrete, TPO, PVC and EPDM roof systems. It includes a cleaner to prepare the substrate for priming; two primers to improve adhesion of the topcoat; a multipurpose sealant for use with reinforcement roofing fabric to complete repair and maintenance tasks; three topcoats—Silicone Roof Coating (available in white and gray), Silicone Masonry Wall Coating (available in white and gray) and Silicone Skylight Coating; and a cleaner to wash tools and equipment. All products are solvent-free and comply with VOC regulations throughout North America.