TPO System Delivers Energy Efficiency for Company Headquarters

TurnKey Corrections constructed a new 115,000-square-foot in facility in River Falls, Wis.

TurnKey Corrections constructed a new 115,000-square-foot in facility in River Falls, Wis.

If you want it done right, do it yourself. Company owners Todd Westby and Tim Westby take a hands-on approach to running TurnKey Corrections, the River Falls, Wisconsin-based company that provides commissary and jail management services to county corrections facilities nationwide. The Westby brothers also take pride in the fact that TurnKey manufactures the kiosks it provides to its clients and develops and owns the proprietary software used to run them.

So, it’s perhaps not surprising that, when building the company’s new headquarters, Todd Westby, the company’s CEO, founder and general manager, served as the general contractor. Or that he had definite ideas regarding the roofing system that would be installed. Or that he was more than willing to get his hands dirty during the installation process.

Founded in 1998, TurnKey Corrections helps corrections facilities streamline and lower the cost of delivering a variety services to inmates, including commissary, email and email-to-text communication, video visitation, law library access, and paperless intra-facility communication and documentation. Following several years of robust growth, the company had outgrown its three existing buildings. So, it constructed a new 115,000-square-foot facility to bring all operations, including 50,000 square feet of office space and a 65,000 square-foot warehouse where commissary items are stored prior to shipment to corrections facilities, under a single roof and accommodate future success.

“We wanted to be involved in the project from beginning to end so we knew what we were getting and how it was built,” Todd Westby says of the decision to keep construction management in-house. “We wanted to know about anything and everything that was being built for the company in this building.”

In planning the project, Westby initially set two key criteria for the roofing system: that the building would be made watertight as quickly as possible so concrete slab pours and other interior work could be completed, and that the roof would be covered by a warranty of at least 20 years. The design-build firm’s initial plans called for a ballasted EPDM roofing system, but Rex Greenwald, president of roofing contractor TEREX Roofing & Sheet Metal LLC of Minneapolis, suggested a white TPO system, noting that it would meet the quick installation and warranty goals while also enhancing the building’s energy efficiency. Westby was intrigued and, after some research, agreed to the recommendation. In addition to helping reduce cooling costs during summer months, the reflective surface would allow a blanket of snow to remain on the roof during winter months to provide additional insulation.

The TPO roofing system was constructed over a 22-gauge metal fabricated roof deck.

The TPO roofing system was constructed over a 22-gauge metal fabricated roof deck.

The Roof System

The TPO roofing system included a 22-gauge metal fabricated roof deck; two 2.5-inch-thick layers of Poly ISO insulation from Mule-Hide Products Co., with tapered insulation saddles and crickets to aid drainage; and 811 squares of 60-mil white TPO membrane from Mule-Hide Products Co. The insulation and membrane were mechanically attached using the RhinoBond System from OMG Roofing Products. Cast iron roof drains, designed and installed by a plumber, were used rather than scuppers and downspouts—a practice that the TEREX team strongly recommends to prevent freezing during the cold Upper Midwest winters. Walkways lead to the mechanical units, protecting the membrane from damage when maintenance personnel need to access the equipment.

The TEREX team finds the RhinoBond System to be the most efficient and economical attachment method for TPO systems. Specially coated metal plates are used to fasten the insulation to the roof deck and then an electromagnetic welder is used to attach the membrane to the plates. The membrane is not penetrated, eliminating a potential entry point for moisture. And while other mechanical attachment methods require the crew to seam as they go, the RhinoBond System allows them to lay the entire membrane (a task which must be completed in good weather conditions) at once and go back later to induction weld the seams and plates, which can be done when Mother Nature is slightly less cooperative.

Greenwald estimates that the switch from the originally specified ballasted EPDM system to the TPO roofing system and RhinoBond System shaved at least 10 percent off the installation time and reduced the roof weight by 10 pounds per square foot.

Having Westby on-site as the general contractor also sped up the project considerably, Greenwald notes. “He was a huge asset to all of the subcontractors,” he explains. “We could get construction questions answered quickly and could talk through issues and procedures on a timely basis.”

And the most memorable moment in the project for Greenwald was seeing Westby working side-by-side with his crew. “One day we had a delivery truck show up, and Todd jumped on the forklift and helped us unload the truck.”

As sought from the project’s outset, the roofing system is backed by a 20-year, no-dollar-limit labor and material warranty.

With one winter of use in the rearview mirror, the roofing system has exceeded Westby’s expectations. Warehouse space was doubled, but heating costs have been cut in half. The 10-unit heating system also is able to keep the warehouse a uniform temperature, without the cold spots that were common in the old building.

“It really is a beautiful, very efficient and organized-looking roof,” Greenwald says.

Virginia Tech Study Measures the Impact of Membranes on the Surrounding Environment

Equipment tripods are set up to hold air temperature and EMT temperature sensors.

Equipment tripods are set up to hold air temperature and EMT temperature sensors.

For much of the past decade, the debate over when and where to install reflective roofing has been guided by two basic assumptions: first, since white roofs reflect heat and reduce air conditioning costs, they should be used in hot climates. Second, since black membranes absorb heat, they should be used in cool-to-colder climates to reduce heating costs. This reasoning has been broadly accepted and even adopted in one of the most influential industry standards, ASHRAE 90.1, which requires reflective roofing on commercial projects in the warm-weather portions of the United States, Climate Zones 1–3.

But as reflective membranes have become more widely used, there has been a growing awareness that the choice of roof color is not simply a matter of black or white. Questions continue to be debated not only about the performance and durability of the different types of membranes, but on the impact of other key components of the roof system, including insulation and proper ventilation. The issue of possible condensation in cooler or even cold climates is garnering more attention. Given these emerging concerns, the roofing community is beginning to ask for more detailed, science-based information about the impact of reflective roofing.

One recent area of inquiry is centering on the impact of “the thermal effects of roof color on the neighboring built environment.” In other words, when heat is reflected off of a roofing surface, how does it affect the equipment and any other structures on that roof, and how might the reflected heat be impacting the walls and windows of neighboring buildings? Put another way, where does the reflected heat go?

THE STUDY

To help answer those questions, the Center for High Performance Environments at Virginia Tech, supported by the RCI Foundation and with building materials donated by Carlisle Construction Materials, designed and implemented a study to compare temperatures on the surface and in the air above black EPDM and white TPO membranes. In addition, the study compared temperatures on opaque and glazed wall surfaces adjacent to the black EPDM and white TPO, and at electrical metallic tubing (EMT) above them.

Specifically, the Virginia Tech study was designed to answer the following questions:

  • What is the effect of roof membrane reflectivity on air temperatures at various heights above the roof surface?
  • What is the effect of roof membrane reflectivity on temperatures of EMT at various heights above the roof surface?
  • What is the effect of roof membrane reflectivity on temperatures of opaque wall surfaces adjacent and perpendicular to them?
  • What is the effect of roof membrane reflectivity on temperatures of glazed wall surfaces adjacent and perpendicular to the roof surface?

To initiate the study, the Virginia Tech team needed to find an existing roof structure with the appropriate neighboring surfaces. They found a perfect location for the research right in their own backyard. The roof of the Virginia-Maryland College of Veterinary Medicine at Virginia Tech was selected as the site of the experiment because it had both opaque and glazed wall areas adjacent to a low-slope roof. In addition, it featured safe roof access.

In order to carry out the study, 1.5 mm of reinforced white TPO and 1.5 mm of non-reinforced black EPDM from the same manufacturer were positioned on the roof site. A 12-by-6-meter overlay of each membrane was installed adjacent to the opaque wall and a 6-by-6-meter overlay of each was installed next to the glazed wall. At each “location of interest”—on the EPDM, on the TPO, and next to the opaque and glazed walls—the researchers installed temperature sensors. These sensors were placed at four heights (8, 14, 23, and 86 centimeters), and additional sensors were embedded on the roof surface itself in the TPO and EPDM. Using these sensors, temperatures were recorded on bright, sunny days with little or no wind. The researchers controlled for as many variables as possible, taking temperature readings from the sensors on and above the EPDM and TPO on the same days, at the same time, and under the same atmospheric conditions.

The roof of the Virginia-Maryland College of Veterinary Medicine at Virginia Tech is the site of the experiment because it has opaque and glazed wall areas adjacent to a low-slope roof.

The roof of the Virginia-Maryland College of Veterinary Medicine at Virginia Tech is the site of the experiment because it has opaque and glazed wall areas adjacent to a low-slope roof.

THE RESULTS

The output from the sensors showed that at the surface of the roof, the black membrane was significantly hotter than the white membrane, and remained hotter at the measuring points of 8 cm and 14 cm (just over 3 inches and 5.5 inches, respectively). However, the air temperature differences at the sensors 23 centimeters (about 9 inches) and 86 centimeters (just under three feet) above the surface of the roof were not statistically significant. In other words, at the site the air temperature just above the white roof was cooler, but beginning at about 9 inches above the roof surface, there was no difference in the temperature above the white and black membranes.

On the precast concrete panel adjacent to the TPO and EPDM, temperatures were warmer next to the TPO than adjacent to the EPDM, leading the study authors to hypothesize that the TPO reflected more heat energy onto the wall than did the EPDM. Exterior glazing surface temperatures were found to be approximately 2 degrees Celsius hotter adjacent to the TPO overlay as compared to the EPDM overlay.

Elizabeth Grant led the team that designed and implemented the study. She says her findings show that you need to take the entire environment into account when designing a roof system. “You need to think about what’s happening on top of the roof,” she says. “Is it adjacent to a wall? Is it adjacent to windows? Is it going to reflect heat into those spaces?”

Samir Ibrahim, director of design services at Carlisle SynTec, believes the study results will help frame additional research. “These findings are an important reminder that the full impact of reflective roofing on a building and on surrounding buildings is not fully understood,” he says. “Additional research and joint studies, covering different climatic conditions, are certainly warranted to broaden the knowledge and understanding of the true impact on the built-environment.”

OMG RhinoBond Projects Are Being Completed Across Europe

OMG Roofing’s RhinoBond System has left marks across Europe with more than 125 completed projects and more in the pipeline. Collectively, these projects represent more than 300,000 square meters (3.2 million square feet) of single-ply roofing.

“In last two years, the RhinoBond System has started to take off across Europe, as more roofing contractors have seen the roof performance benefits that the system can offer,” states Web Shaffer, vice president of marketing for OMG Roofing Products. “We have completed projects across Europe and we are expanding to new countries in the region, most recently, into South East Europe.”

RhinoBond is a method for installing thermoplastic and now also clean EPDM membrane. The system consists of a stand-up induction welding tool and magnetic cooling clamps. Contractors install roofing insulation using fasteners and specially coated plates designed specifically for the type of membrane being installed – PVC, TPO or Clean EPDM. Each plate is then bonded to the roof membrane installed over the top with the RhinoBond plate welding tool. The result is a roofing system that can provide wind performance with fewer fasteners, fewer membrane seams and zero penetrations of the new membrane.

The RhinoBond System is approved for use in Europe by many roof system providers, including Bauder, Carlisle/Hertalan, Danosa, Fatra, FDT, Firestone, GAF, IcoPal, IKO, Renolit, Sika, Siplast, and Soprema/Flag.

Headquartered in Agawam, Mass., OMG Roofing Products is a supplier of commercial roofing products including specialty fasteners, insulation adhesives, roof drains, pipe supports, emergency roof repair tape as well as productivity tools such as RhinoBond. The company’s focus is delivering products and services that improve contractor productivity and enhance roof system performance. For additional information, please contact OMG Roofing Products at (413)789-0252 or visit the OMG Roofing website.

Project Profiles: Education Facilities

Maury Hall, U.S. Naval Academy, Annapolis, Md.

TEAM

Roofing Contractor: Wagner Roofing, Hyattsville, Md.
General Contractor: C.E.R. Inc., Baltimore, (410) 247-9096

The project included 34 dormers that feature double-lock standing-seam copper and fascia metal.

The project included 34 dormers that feature double-lock standing-seam copper and fascia metal.

ROOF MATERIALS

Wagner Roofing was awarded the complete replacement of all roof systems. These included an upper double-lock standing-seam copper roof system, a bullnose copper cornice transition, slate mansard, 34 dormers with double-lock standing-seam copper and fascia metal, eight copper hip metal caps and a continuous built-in gutter with decorative copper fascia. Each of the dormers also had a copper window well.

The upper standing-seam roof was removed and replaced with 24-inch-wide, 20-ounce copper coil rollformed into 1-inch-high by 21-inch-wide continuous standing-seam panels that matched the original profile. The eave bullnose, which also served as the mansard flashing, was removed and returned to Wagner Roofing’s shop where it was replicated to match the exact size and profile.

The 34 dormer roofs were replaced with 20-inch-wide, 20-ounce copper coil formed into 1-inch-high by 17-inch- wide continuous standing-seam panels. The decorative ornate fascia of the dormers was carefully removed and Wagner’s skilled craftsmen used it as a template to develop the new two-piece copper cornice to which the roof panels locked. The cheeks and face of the dormers were also re-clad with custom-fabricated 20-ounce copper.

The oversized built-in-gutter at the base of the slate mansard was removed and replaced with a new 20-ounce copper liner custom-formed and soldered onsite. The replacement included a specialty “bull-nosed” drip edge at the base of the slate and an ornate, custom-formed fascia on the exterior of the built-in gutter. The decorative copper fascia included 85 “hubcaps”, 152 “half wheels” and 14 decorative pressed-copper miters. The original hubcap and half-wheel ornaments were broken down and patterns were replicated. Each ornamental piece was hand assembled from a pattern of 14 individual pieces of 20-ounce copper before being installed at their precise original location on the new fascia. The miters were made by six different molds, taken from the original worn pieces, to stamp the design into 20-ounce sheet copper.

In all, more than 43,000 pounds of 20-ounce copper was used on the project.

Copper Manufacturer: Revere Copper Products

ROOF REPORT

Maury Hall was built in 1907 and was designed by Ernest Flagg. Flagg designed many of the buildings at the U.S. Naval Academy, including the Chapel, Bancroft Hall, Mahan Hall, the superintendent’s residence and Sampson Hall. His career was largely influenced by his studies at École des Beaux-Arts, Paris. Examples of Flagg’s Beaux-Arts influence can be found in the decorative copper adorning the built-in gutter on building designs.

Maury Hall currently houses the departments of Weapons and Systems Engineering and Electrical Engineering. The building sits in a courtyard connected to Mahan Hall and across from its design twin, Sampson Hall.

PHOTO: Joe Guido

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Project Profiles: Retail

Sierra Nevada Brewery, Mills River, N.C.

About 58,000 pounds of copper were installed on the brewery.

About 58,000 pounds of copper were installed on the brewery.

TEAM

Roofing Contractor: The Century Slate Roofing Co., Durham, N.C.
Architect: Matthew Galloway of Russell Gallaway Associates Inc., Chico, Calif.

ROOF MATERIALS

Approximately 423 squares of 1/2-inch-thick, 18-inch-tall by random width Unfading Green Slates were installed by hand on the project. This was close to 750,000 pounds of slate, or 375 tons.

About 3,000 feet of custom copper gutters and downspouts, conductor heads and 100 squares of painted standing-seam panels were fabricated, and pre-built copper clad dormers and decorative copper cornices were installed.

The project also included 35 squares of copper standing-seam roofing, 25 squares of soldered copper flat-seam roofing and 115 squares of copper wall cladding. About 58,000 pounds of copper were installed on the brewery.

Everything on the building is oversized and that meant everything had to be built to support the heavy structural loads and live loads from wind and mountain snow. The large roof faces called for 10-inch custom copper gutters. When you have gutters that large in the mountains of North Carolina you have to consider the extraordinary weight of the annual snow.

In addition to snow guards being installed on the slate roof, custom 1/4-inch-thick copper gutter brackets fastened the gutter to the fascia. It is typical on steel-framed construction, particularly on this scale, that the framing is out of square and there is widely varying fascia and rake dimensions.

Approximately 423 squares of 1/2-inch-thick, 18-inch-tall by random width Unfading Green Slates were installed by hand on the project.

Approximately 423 squares of 1/2-inch-thick, 18-inch-tall by random width Unfading Green Slates were installed by hand on the project.

However, these items should not appear out of square or have varying dimensions. Great care had to be taken to measure and custom bend onsite all the detail flashings so everything appeared perfect. This took many skilled craftsmen, a great deal of time and the absolute drive to provide the highest quality work.

Slate Manufacturer: Evergreen Slate Co. Inc.
Copper Fabricator: K&M Sheet Metal LLC
Supplier of Underlayment, Copper Sheets and Coil, Insulation and Nailbase Sheathing: ABC Supply Co. Inc.

ROOF REPORT

The new-construction project began in November 2013 and was completed in September 2015.
The team completed the slate installation so well that The Century Slate Co. was awarded the 2015 Excellence in Craftsmanship Award by Evergreen Slate for the project.

PHOTOS: The Century Slate Roofing Co.

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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.”

Projects: Office and Warehouse

BMC ISSAQUAH, ISSAQUAH, WASH.

Because of the steep slope of this roof, the Columbia Roofing & Sheet Metal crew installed 60-mil Sureweld HS (High Slope) TPO.

Because of the steep slope of this roof, the Columbia Roofing & Sheet Metal crew installed 60-mil Sureweld HS (High Slope) TPO.

Team

Roofing Contractor: Columbia Roofing & Sheet Metal, Kent, Wash.
Project Foreman: Rudy Sanchez

Roof Materials

Because of the steep slope of this roof, the Columbia Roofing & Sheet Metal crew installed 60-mil Sureweld HS (High Slope) TPO. HS TPO contains more fire-retardant chemicals in the membrane to help decrease the spread of fire. In addition, 1/4-inch Securock Glass-Mat Roof Board was installed, which gave the building a Class A fire rating while helping protect against moisture and mold.

TPO Manufacturer: Carlisle Syntec Systems
Roof Board Manufacturer: USG

Roof Report

BMC Issaquah manufactures doors and high-end cabinetry. The industrial building features a 525-square barrel roof that was very wet and experienced dry rot. The crew replaced nearly 150 sheets of plywood throughout the project.

The main challenge during installation was safety because of the extreme slope. The barrel roof is nearly 60-feet tall from the bottom to the top of the barrel, making installation on the edges difficult because crewmembers had to hot-air weld rolled product on a nearly vertical surface. The HS TPO added another level of difficulty while welding along the edges.

The project was completed on May 1, 2015.

PHOTO: Columbia Roofing & Sheet Metal

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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

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Stop Leaks Around Vent Pipes

The Perma-Boot is a gasket-less, high-performance pipe boot system designed to permanently repair the most common type of roof leak—the leak around the vent pipes that penetrate the roof.

The Perma-Boot is a gasket-less, high-performance pipe boot system designed to permanently repair the most common type of roof leak—the leak around the vent pipes that penetrate the roof.

The Perma-Boot is a gasket-less, high-performance pipe boot system designed to permanently repair the most common type of roof leak—the leak around the vent pipes that penetrate the roof. Perma-Boot slides over an existing boot, preventing future leaks. Installation takes a few minutes; no tools are required. The product is designed for all standard roof pitches: 3:12 to 12:12. It is made of durable TPO and guaranteed for the life of the shingles.