The BTI-Greensburg John Deere Dealership Installs Tornado-Resistant Daylighting Systems and Other Sustainable Materials

On the night of May 4, 2007, brothers Kelly and Mike Estes saw their BTI-Greensburg John Deere Dealership obliterated by an EF5 tornado nearly 2-miles wide (according to the Enhanced Fujita Scale, which rates the strength of tornados by the damage caused; view the scale on page 3). Astoundingly, 95 percent of their town—Greensburg, Kan.—was also destroyed that day. The tornado did much more than rip roofs off buildings and toss things around; it turned the entire community into what looked like kindling.

Rarely do communities get hit by an EF5 tornado, which can come about when air masses collide. Sometimes warm, humid air from the Gulf of Mexico rises above drier air from the Southwest deserts in the U.S. This can create unstable conditions resulting in thunderstorms and worse. A strong collision of air masses creates a strong storm. Additionally, wind patterns and the jet stream can magnify the storm, resulting in what people refer to as “the perfect storm”.

After being completely destroyed by an EF5 tornado, the BTI-Greensburg John Deere Dealership has been rebuilt in Greensburg, Kan., in a better, greener way.

After being completely destroyed by an EF5 tornado, the BTI-Greensburg John Deere Dealership has been rebuilt in Greensburg, Kan., in a better, greener way.

Despite the large-scale losses incurred by the entire town, 100 customers and friends of the Estes family showed up the morning of May 5 to help them salvage what remained of their business. Shortly after the tornado disaster, Kansas Gov. Kathleen Sebelius stated her wish that Greensburg become the “the greenest city in the state”.

As part of their commitment to their community, Kelly, Mike and their family decided to rebuild their business in a better, greener way. They wanted the new 28,000-square-foot prefabricated metal building to be the world’s greenest farm-machinery facility; attain a LEED Platinum rating from the Washington, D.C.-based U.S. Green Building Council; and use the least energy possible. One of the most important considerations was using building materials that could withstand future tornados.

DAYLIGHTING

To help achieve LEED Platinum and outlast any future high-velocity winds, they incorporated 12 Daylighting Systems in their retail area’s roof to showcase their merchandise; reduce lighting energy costs; and flood the area with natural light, a benefit for customers and employees.

The Daylighting Systems capture light through a dome on the roof and channel it down through a highly reflective tube. This tubing is more efficient than a traditional drywall skylight shaft, which can lose over half of the potential light. The tubing fits between rafters and installs with no structural modification. At the ceiling level, a diffuser that resembles a recessed light fixture spreads the light evenly throughout the room.

The dome is made from high-quality acrylic resin that is specifically formulated for increased impact strength, chemical- and weather-resistance, and high clarity (a polycarbonate inner dome is used for high-velocity hurricane zones). Domes are engineered to deflect midday heat and maximize low-angle light capture. The tubing is made from puncture-proof aluminum sheet coated with the highly reflective material for maximum light transfer. The units (independently tested by Architectural Testing in Fresno, Calif.) comply with various building codes including the 2009 International Building Code and 2010 Florida Building Code, including high-velocity hurricane zones.

“When our power went out one time for four hours, we were able to keep the shop open and operating due to daylight strategies, which includes the Daylighting Systems,” notes Mike Estes. “We didn’t anticipate this benefit but we’re really happy to have this bonus.”
PHOTO: SOLATUBE INTERNATIONAL INC.

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Asphalt-based Low-slope Roof Systems Provide Long-term Service Life

Asphalt-based roof systems have a long-standing track record of success in the roofing industry. In fact, asphalt-based roof systems have more than a century of use in the U.S. Building owners, roofing specifiers and contractors should not lose sight of this fact. It is important to understand why asphalt roofing has been successful for so long. Asphalt roofs demonstrate characteristics, such as durability and longevity of materials and components, redundancy of waterproofing, ease and understanding of installation, excellent tensile strength and impact resistance. Each of these characteristics helps ensure long-term performance.

Using a composite built-up/ modified bitumen roof system provides redundancy helping ensure durability and longevity. Surface reflectivity and a multilayer insulation layer provide excellent thermal resistance. Quality details and regular maintenance will provide long-term performance. PHOTO: Advanced Roofing

Using a composite built-up/
modified bitumen roof system provides redundancy helping ensure durability and longevity. Surface reflectivity and a multilayer insulation layer provide excellent thermal resistance. Quality details
and regular maintenance will provide long-term performance. PHOTO: Advanced Roofing

There are two types of asphalt-based low-slope roof systems: modified bitumen (MB) roof systems and builtup roof (BUR) systems. MB sheets are composed primarily of polymer-modified bitumen reinforced with one or more plies of fabric, such as polyester, glass fiber or a combination of both. Assembled in factories using optimal quality-control standards, modified bitumen sheets are manufactured to have uniform thickness and consistent physical properties throughout the sheet. Modified bitumen roof systems are further divided into atactic polypropylene (APP) and styrene butadiene styrene (SBS) modified systems. APP and SBS modifiers create a uniform matrix that enhances the physical properties of the asphalt. APP is a thermoplastic polymer that forms a uniform matrix within the bitumen. This matrix increases the bitumen’s resistance to ultraviolet light, its flexibility at high and low temperatures, and its ability to resist water penetration. SBS membranes resist water penetration while exhibiting excellent elongation and recovery properties over a wide range of temperature extremes. This high-performance benefit makes SBS membranes durable and particularly appropriate where there may be movement or deflection of the underlying deck.

BUR systems consist of multiple layers of bitumen alternated with ply sheets (felts) applied over the roof deck, vapor retarder, and most often insulation or coverboard. BUR systems are particularly advantageous for lowslope applications. The strength of the system comes from the membrane, which includes the layers of hot-applied bitumen and the reinforcing plies of roofing felt.

FACTORS FOR LONG-TERM PERFORMANCE AND SERVICE LIFE

It is important for building owners and roof system designers to recognize the principles of long-lasting, high-performance roof systems. Roof longevity and performance are determined by factors that include building and roof system design, job specifications, materials quality and suitability, application procedures and maintenance. The level of quality in the workmanship during the application process is critical.

Longevity and performance start with proper design of the asphalt-based roof system. Proper roof system design includes several components: the roof deck, a base layer supporting a vapor retarder or air barrier when necessary, multi-layer insulation and a coverboard, the asphaltic membrane, appropriate surfacing material or coating, and the attachment methods for all layers. Roof consultants, architects and roof manufacturers understand proper design. Roof design needs to follow applicable code requirements for wind, fire and impact resistance, as well as site-specific issues, such as enhanced wind resistance design, positive drainage and rooftop traffic protection. Roof designers can provide or assist with the development of written specifications and construction details that are specific to a roofing project for new construction or reroofing.

Low-slope asphalt-based roof systems are redundant; they are multi-layered systems. BUR systems include a base sheet, three or four reinforcing ply sheets and a surfacing, either aggregate (rock) or a cap sheet. MB sheets include one and sometimes two reinforcing layers and are commonly installed over a substantial asphaltic base sheet. Modified bitumen roofs can be granule surfaced, finished with reflective options or coated after installation. Aggregate, granules, films and coatings add UV protection, assist with fire resistance, provide durability to the roof system and can improve roof aesthetics.

An asphaltic cap sheet with a factory-applied reflective roof coating is installed over three glass-fiber ply sheets and a venting base sheet. The reflective coating reduces heat gain, and insulating concrete provides a stable substrate and high R-value. PHOTO: Aerial Photography Inc.

An asphaltic cap sheet with a factory-applied reflective roof coating is installed over three glass-fiber ply sheets and a venting base sheet. The reflective coating reduces heat gain, and insulating concrete provides a stable substrate and high R-value. PHOTO: Aerial Photography Inc.

Coverboards provide a durable layer immediately below the membrane, are resistant to foot traffic and separate the membrane from the thermal insulation layer. Protecting the thermal insulation helps maintain the insulation R-value as specified and installed.

Asphalt is a durable and long-lasting material for roof membranes and flashings. Asphalt is stable under significant temperature swings and can be highly impact resistant. Various reinforcements can be used to increase an asphaltic membrane’s durability. All asphaltic membranes are reinforced, during installation (BUR) or the manufacturing process (MB membranes). Polyester reinforcement has excellent elongation, tensile strength and recovery. It provides good puncture resistance and stands up well to foot traffic. Glass fiber reinforcement resists flame penetration and provides excellent tensile strength and dimensional stability.

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An ERA Study Proves EPDM Easily Lasts More than 30 Years

More and more building owners are seeing the light: Roof systems based on historical in situ performance for more than 30 years are the best roof system choice to benefit the environment. EPDM roof membrane has been utilized as a roof cover for more than 40 years, and there are numerous examples of ballasted roofs greater than 30-years old still performing. New seaming technologies, thicker membrane and enhanced design are creating roof systems with projected 50-year service lives. EPDM roof covers’ physical characteristics have changed little in 30 years, and because potential for 50-year-plus service life is possible, they are a solid choice of design professionals, building owners and school district representatives who truly desire a roof system that benefits the environment.

PHOTO 1: This ballasted 45-mil EPDM roof system has been in service for 32 years.

PHOTO 1: This ballasted 45-mil EPDM roof system has been in service for 32
years.

In 2010, the Washington, D.C.-based EPDM Roofing Association (ERA) was determined to answer the question: “How long can an EPDM roof perform?” Consequently, roof membrane samples from five roof systems with a minimum age of 30 years were obtained for testing of their physical properties. The physical and mechanical properties evaluated (using relevant ASTM standards) were overall thickness, tear resistance, tensile set, tensile strength and elongation, and water absorption. The results were positive, showing that even after 30 years of infield exposure nearly all the physical characteristics of EPDM membrane meet or exceed ASTM minimums. But the question of how long EPDM roofs could last remained. Thus, a second phase of testing was undertaken.

These properties were studied for “as received” and “after heat-conditioning” for up to 1,500 hours at 240 F. Results showing how these membranes performed before and after heat-conditioning are presented with the intent of defining characteristics for long-term service life of roof membranes.

TESTING PHASE ONE

Ethylene-propylene-diene terpolymer (EPDM) has been used in waterproofing and roof applications for more than 45 years in North America. Introduced into the roofing market in the 1960s, EPDM grew, especially after the 1970s oil embargo, to be a roofing membrane choice for new construction and roofing replacement projects. EPDM has achieved long-term in situ performance in part because of its chemical structure, mostly carbon black, which resists ozone and material decomposition, as well as degradation caused by UV light, which is the No. 1 degradation element to roofing materials exposed to the sun (see photo 1). The carbon black also provides reinforcement, yielding improved physical and mechanical properties.

Long-term performance of roof-cover material is dependent upon its resistance to the combined effects of ponding water, UV radiation, ozone, heat and thermal cycling. Geographical location can exacerbate or reduce the impact of climatic factors. In ballasted systems, the ballast acts to provide protection from the UV rays and minimizes the effect of climatic influences.

ERA’s study had three specific goals:

    1. Verify the long-term performance characteristics of EPDM membranes over 30 years. (At the time of the study, the only in situ membranes that were around for 30 years were 45-mil EPDM membranes. Currently 60- and 90-mil are the standard choices. It is assumed that results for the 45-mil material can be prorated for the thicker membrane.)

    2. Scientifically validate the empirical sustainability experiences.

    PHOTO 2: This recently installed, ballasted, 90-mil EPDM roof was designed for a 50-year service life.

    PHOTO 2: This recently installed, ballasted, 90-mil EPDM roof was designed for a 50-year service life.

    3. Create a foundation for specifier-to-owner discussions in regard to long-term service life. Five roofs, four ballasted and one fully adhered, with in situ service lives approaching or over 30 years were identified and samples were taken. All roofs were fully performing without moisture intrusion.

The samples were sent for testing per ASTM D4637 for:

  • Elongation
  • Tensile strength
  • Thickness
  • Factory seam strength (psi)

PHOTOS: HUTCHINSON DESIGN GROUP LTD.

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Galvalume-coated Metal Roofs Will Last at Least 60 Years with Minimal Component Repair

The term “infrastructure sustainability” continues to gain importance because of rapidly increasing building infrastructure components around the country needing major repairs and/ or replacements. Consequently, roof maintenance or replacement materials and methods must last at least 60 years; consider LEED v4 from the Washington, D.C.-based U.S. Green Building Council. For more than 30 years, millions of square feet of Galvalume-coated roofs have resisted the atmospheric conditions to which they are exposed with little or no maintenance and are well prepared to continue protecting building interiors for more than 30 additional years. Material science and professional project engineering and installation prove Galvalume-coated metal standing-seam roofs will perform for that period of time.

This is a nine-year-old painted Galvalume roof in Alabama.

This is a nine-year-old painted Galvalume roof in Alabama.

MATERIAL SCIENCE

The first standing-seam metal roof was introduced by Armco Steel Corp., Middletown, Ohio, at the 1932 World’s Fair in Chicago. Armco Steel ceased doing business many years ago, but its standing-seam metal roof design has been adopted by all manufacturers in today’s commercial metal roofing market. The second longest-lasting introduction into this market was in the early 1970s when Bethlehem, Pa.-based Bethlehem Steel introduced a Zinc/Aluminum coating—now known as Galvalume—for carbon-steel metal roofs. This coating, applied to both sides of the steel coil, has been successfully used for the majority of metal standing-seam roofs ever since.

Since Galvalume was introduced, there have been several evaluations, reports and predictions as to how this product would “weather” the test of time. In 2012, the Chicago-based Metal Construction Association (MCA) and Olympia, Wash.-based Zinc Aluminum Coaters Association (ZAC) commissioned a study to perform forensic tests at 14 existing Galvalume standing-seam metal roof sites throughout the country in varying climates and precipitation pH. The average age of these roofs was more than 30 years at the time of testing.

Initially, the sites were selected based on temperature and humidity zones throughout the U.S. As the field results were processed, however, it became apparent the expected lives of these roofs were directly dependent on the precipitation pH levels with very little correlation to temperature and humidity. The building sites chosen were located in the following states:

  • Massachusetts (2 sites)
    This Galvalume roof in Missouri is nine years old.

    This Galvalume roof in Missouri is nine-years old.


    Ohio (3 sites)
    South Carolina (2 sites)
    Georgia (1 site)
    Colorado (1 site)
    New Mexico (1 site)
    Arizona (1 site)
    Oregon (1 site)
    Wyoming (2 sites)

The study was directed by MCA and three independent consultants and their firms, which managed and performed the field work: Rob Haddock of Metal Roof Advisory Group, Colorado Springs, Colo.; Ron Dutton of Ron Dutton Consulting Services LLC, Annapolis, Md.; and me and my firm Metal Roof Consultants Inc., Cary, N.C. This group, plus Scott Kriner, MCA’s technical director, authored the actual report, which was issued by MCA and ZAC in November 2014 and is available online.

The team harvested and analyzed actual field samples of Galvalume-coated metal standing-seam roof panel materials and sealants and examined all the individual roofs’ ancillary components. Finally, it created an experienced assessment of the roofs’ conditions and associated costs to replace.

PHOTOS: METAL ROOF CONSULTANTS INC.

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Metal Roofing Underlayments Protect Structures in Hawaii

The newly constructed Safeway Shopping Center, Honolulu, happens to be the largest Safeway on the Hawaiian Islands. It contains a parking garage below—in part, because of its location in a densely populated neighborhood.

The underlayment manufacturer worked on and approved a design in which the underlayment could be installed directly on the metal deck.

The underlayment manufacturer worked on and approved a design in which the underlayment could be installed directly on the metal deck.

ITS METAL ROOF WAS INSTALLED by Kapolei, Hawaii-based Beachside Roofing, which has been doing business in Hawaii for more than 25 years. The company, which installs all kinds of roofing and waterproofing systems, specializes in high-rise buildings, resorts and complex projects.

The 20,000-square-foot metal roof on the Safeway store had to meet strict color requirements in keeping with the Safeway brand. The color of the roof is Gargoyle, which is a greenish-brown.

The metal roofing was designed to be installed over corrugated 20-gauge steel decks. The underlayment manufacturer worked on and approved a design in which the underlayment could be installed directly on the metal deck.

The metal deck (HSB-36SS type) was installed with the wider corrugations facing up and parallel to the eaves (horizontally). The self-adhering underlayment also was installed horizontally, and the metal panels were then attached to the horizontal corrugations of the deck using panel clips and self-drilling fasteners penetrating through the underlayment into the flattop of the corrugations of the steel deck.

The self-adhering underlayment also was installed horizontally, and the metal panels were then attached to the horizontal corrugations of the deck using panel clips and self-drilling fasteners penetrating through the underlayment into the flattop of the corrugations of the steel deck.

The self-adhering underlayment also was installed horizontally, and the metal panels were then attached to the horizontal corrugations of the deck using panel clips and self-drilling fasteners penetrating through the underlayment into the flattop of the corrugations of the steel deck.

The walkability of the underlayment was an important factor, considering that the roof slope was 4 inches per 12 feet in some places. Also, the 120-day exposure allowance for the underlayment was reassuring, though not necessary for this project.

The metal roofing system included many architectural elements, such as canopies, penthouses and mansards. It covers not just the Safeway supermarket, but also other shops in the Safeway Shopping Center. The way the metal was used architecturally really dressed up the exterior of the project.

Secondary Water Barrier

A self-adhering metal roofing underlayment, like the one on the Safeway Shopping Center, perfectly complements metal roofing panels. The underlayment provides a watertight secondary membrane while the metal panels serve as the primary roof to protect against wind-blown objects and UV radiation. If the primary roof is damaged, the secondary roof acts as the water barrier.

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Built-in Gutters Should Be Carefully Inspected, Restored and Maintained

Sheet-metal gutter linings, whether made of copper, lead or both, are relatively involved and require the services of a highly skilled artisan craftsman.

Sheet-metal gutter linings, whether made of copper, lead or both, are relatively involved and require the services of a highly skilled artisan craftsman.

Built-in gutters may be the most complicated system in the building envelope, yet they are also the most elusive when you start searching for information about them. Sometimes called Yankee gutters, box gutters or even Philadelphia gutters, it’s no wonder they remain a mystery to many. Built-in gutter systems are actually built into the cornice structure and drain through internal or external leaders. They are not readily visible from the ground, further lending to the mystery of their design and function. Because they are integrated into the structure, built-in gutter linings that fail will cause extensive damage to the cornice and sometimes also the interior of the structure.

In “Traditional Rainwater Conductor Systems of the 18th and 19th Centuries,” Karen Dodge of the U.S. National Park Service, Washington, D.C., states built-in gutters were first adopted in North America during the 18th century in high-style Georgian and Federal-style buildings, usually institutional or commercial, where refined architectural qualities were desired. Although built-in gutters are highly functional, they also serve an aesthetic purpose. As structures were erected in the classical order with elaborate cornices and entablature, it became necessary to collect and channel rainwater without detracting from the architectural character of the building. Built-in gutters served this function well, hidden from sight and shedding water to the exterior.

Built-in gutters, today, are typically constructed in the same manner as they have been since the 18th century. They are wooden boxes with bottoms sloped toward the outlets where water is drained to leaders, or conductor pipes, that channel the water away from the building. The first gutters in this style were actually troughs or box gutters, carved out of wood and rubbed with linseed oil or painted to protect the wood. Corners and seams were bonded with lead wedges. Needless to say, maintenance was critical to their success or failure. Later, the advent of sheet lead allowed for broader gutters, as linings covered the wooden troughs. By the end of the century, copper became available in the U.S. and a popular choice for gutter linings because of its durability and the functional nature of the material in a sheet-metal application.

INSPECTION AND MAINTENANCE

The most common sign of water penetration is peeling paint and decay in the wood soffit under the gutter. Other signs are dark stains and mildew or deterioration of masonry. Water infiltration may be visible in attic spaces or areas beneath the gutters where plaster and other interior finishes evidence water damage. The sooner a leak or area vulnerable to failure is addressed, the smaller the scope and cost of repairs. Cleaning out leaves and debris from gutters as often as necessary is essential for durability and proper performance.

Careful inspection by a competent roofer is critical to the longevity and success of the system. He or she will look for defects, such as localized damage caused by fallen limbs or other debris, cracks from expansion and contraction at joints or folds, or pinholes from corrosion. Roofing tar and other bituminous compounds should never be used to patch, repair or coat gutter linings. It makes the condition of the gutter indeterminable, corrodes metal linings, will crack and fail quickly, and cannot be removed without destroying the lining. Ice damming is not uncommon in the winter but should not be removed with sharp tools for obvious reasons.

When tin or terne-coated steel gutter linings fail, water intrusion will occur and cause wood rot. Eventually, architectural details will be lost and replacement will be necessary.

When tin or terne-coated steel gutter linings fail, water intrusion will occur and cause wood rot. Eventually, architectural details will be lost and replacement will be necessary.

RESTORATION

Restoration of long-neglected built-in gutter systems that leak and have caused decay in the cornice and roof structure is often complicated and can be costly. But once the work is completed, a regularly maintained, well-detailed system can last 60 to 100 years or more, depending on the life of the metal lining. A preservation architect or consultant should inspect the building, propose treatment options, develop working drawings and specifications, and supervise bidding and construction. Temporary protection and permanent repairs should be performed by a roofer experienced in this specialty on historic buildings.

“We encourage restoration of historic built-in gutter systems,” says Michael Devonshire, a building conservator and principal at Jan Hird Pokorny Associates, New York. “The use of modern building materials as an adjunct to traditional materials boosts longevity.” Devonshire states the typical steps involved with a built-in gutter restoration involve:

  • Removing the gutter lining and 2 feet of the roof covering above the curbing of the gutter.
  • Repairs to rotted or otherwise deteriorated frame work. Where rafter ends or lookouts are rotted, install sisters (new rafter ends adjacent to old ones) or scarf in new wood and sisters.
  • Replacing the old wooden gutter bottom with a sustainable wood material, such as cedar or kilndried- after-treatment (KDAT) plywood. KDAT is treated for resistance to decay, minimal expansion and contraction, and increased longevity.
  • Installing the gutter lining: an elastomeric ice-and-water shield on the bottom (not always required); building felt; a slip-sheet of rosin paper; and copper on top (16 or 20 ounce, depending on the dimensions of the gutter).
  • Installing the roof covering on the roof deck above the gutter. This includes 2 feet of elastomeric ice-and-water shield (or copper flashing) beneath.
  • Repairing or replacing cornice mouldings, brackets and other architectural woodwork.

PHOTOS: WARD HAMILTON

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Deft Planning and Skillful Moves Play Out on the Reroof of the World’s Largest Water Filtration Plant

Reroofing the 10.3-acre surface of Chicago’s highly sensitive James W. Jardine Water Filtration Plant posed logistical challenges on par with the building’s magnitude. Phasing to ensure the plant continued to supply fresh water to its 5 million customers in the city of Chicago and its suburbs, the need for complete containment areas, roof-load restrictions, unique stainless-steel expansion joints and the Department of Homeland Security’s onsite presence all made for intricate operations. But John Cronin, president of Chicago-based Trinity Roofing Service, says Mother Nature was his toughest challenge.

The James W. Jardine Water Filtration Plant arguably was the largest and most complex roofing project in Chicago during the past decade.

The James W. Jardine Water
Filtration Plant arguably was the largest and most complex roofing project in Chicago during the past
decade.

“Conducting construction on the Lake Michigan waterfront during Chicago’s harshest winter in 30 years [2013-14] was by far the hardest part of this job. Driving rain, wind, black ice and snow—it was unmerciful,” asserts Cronin. “Constant communication had to be our priority, because we could go to the site in the morning and discover that weather made impossible the sequence of work we had planned. Senior Project Manager J.J. Matthews, Job Superintendent Rob Reno and I had to be incredibly flexible to keep the job moving.”

Water Protection

The water-treatment plant’s 50-year-old coal-tar roof and concrete roof deck had been leaking, which created potential health concerns. The plant supplies approximately 1 billion gallons of clean water a day, which meant many concrete filter beds had to remain operational and free of contamination during construction. Filter beds beneath the phased work area were drained. To protect the drained beds, Trinity cut a hole in the roof and erected a specialized watertight “shoe box” work zone, extending 6-feet down. These shoebox areas consisted of a plywood scaffolding platform blanketed by a 60-mil membrane. Inside the box, existing structural steel had to be sand blasted free of lead paint, inspected and replaced in some spots. At any given time, the team had two 56,000-square-foot scaffolding platforms in place.

Winter winds blew snow across the flat roof and down into these protection zones carrying multiple forms of contamination. Rooftop bird droppings were one source. Asbestos from the original 1960s roof was another. The team had to bring in heat torpedoes (portable forced-air or convection heaters) to melt the snow and divert it through custom-made gutters into cisterns to be hauled offsite so workers could access the steel.

Protecting materials from the elements was also paramount. More than 1,000 rolls of fleece-backed membrane had to remain completely dry. In addition, cellular glass roof insulation (specified from Belgium for its proven 50-year track record on the facility) had an eight-week timeframe for production and overseas delivery, making critical that each square of insulation stayed in pristine condition. Chicago rain can fall in isolated pockets, so every load had to be fully secured with tarp, even on seemingly sunny days.

The harsh Chicago winter of 2013- 14 didn’t stop Trinity Roofing Service from completing the twoyear project on schedule. Seven miles of backer rod are being laid between seams of concrete roof channels despite snow and ice.

The harsh Chicago winter of 2013-14 didn’t stop Trinity Roofing Service from completing the two-year project on schedule. Seven miles of backer rod are being laid
between seams of concrete roof channels despite snow and ice.

“It was an ongoing job to impress the importance of covering all the materials that came to the site, especially at the slightest hint of rain,” Cronin says. “It worked, though. We fully inspected every material load that came to the job site. Out of more than 712,000 board feet of new insulation, none of it was rejected thanks to our strictly enforced quality-control program.”

Despite the snow and ice accumulation on staging areas, no salt was allowed on the property for fear of water contamination, which meant Trinity also dealt with slippery walking and driving surfaces.

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Standards for Testing Solar PV Modules and Panels

For more than a decade, the demand for grid-connected solar installations in the U.S. has been on the rise, in part, because of economic and legislative incentives that encourage and often subsidize the installation of photovoltaic (PV) modules for residential and commercial applications. In the interest of improving energy efficiency, property owners, including businesses and homeowners, are turning to their roofs to support the PV systems.

Solar PV panels are installed on a roof by a mounting or racking system. Building-integrated PV modules replace the roofing material and become a part of the roof.

Solar PV panels are installed on
a roof by a mounting or racking
system. Building-integrated PV
modules replace the roofing material
and become a part of the roof.

A U.S. Solar Market Insight report published this year by the Solar Energy Industries Association, Washington, D.C., found that grid-connected solar electric installations were producing 13 GW of energy through the end of 2013—enough to power nearly 2.2 million homes in the U.S. That’s equivalent to 4,751 MW of solar PV installed in 2013.

There are two main types of PV modules that are being installed on steep- and low-slope roofs today: PV modules that are secured to the roof by a mounting or racking system and building-integrated PV modules (BIPV) that replace the roofing material and become part of the roof. The variety of components and installation techniques lends itself to closer scrutiny in testing each PV module.

ANSI/UL 1703

For more than a decade, manufacturers of flat-plate PV modules and solar panels have had their products tested and certified to meet the ANSI/UL 1703 regulatory standard to ensure their safety, performance and reliability before entering the market.

However, following recent field failures in which fire impacted the module differently than anticipated because of the way it was installed or interacted with the roof, as well as how the PV performed in extreme weather conditions, the ANSI/UL 1703 standard was updated for fire-resistance testing and classification requirements.

The changes to ANSI/UL 1703 require that testing for PV systems not solely be based on the rating for the individual modules, but instead that it takes into account a combined system rating. Stand-alone PV modules and PV modules with mounting or racking systems in combination with the roof covering must receive a fire rating, denoted by Class A, B or C. However, the same testing procedures do not apply for BIPV systems. They will continue to be tested to ANSI/UL 790, “Standard Test Methods for Fire Tests of Roof Coverings”.

Fire resistance testing, such as Spread of Flames and Burning Brand tests, on solar PV roofing installations are tested in a lab and in the field.

Fire resistance testing, such as Spread of Flames and Burning Brand tests, on solar PV roofing installations are tested in a lab and in the field.

Because of the changes to the ANSI/UL 1703 standard, manufacturers will be required to incorporate new and different testing procedures or potentially need to re-test previously tested products to comply with the standard. A PV panel will be required to obtain a classification “type” with construction review and testing, in addition to obtaining a fire rating for the PV system, which incorporates a module, mounting system and roof covering. The California State Fire Marshal announced the changes to ANSI/UL 1703 will go into effect in California starting Jan. 1, 2015, while changes to the code are set to go into effect in all states and other countries by Jan. 1, 2016.

THIRD-PARTY TESTING

Several solar PV manufacturers regularly work with companies, like Intertek, to ensure the quality and safety of their products, processes and systems. Intertek is one of the four Nationally Recognized Test Laboratories, including UL, CSA and TUV, recognized by Washington-based OSHA to conduct the ANSI/UL 1703 and ANSI/UL 790 testing in the U.S. Intertek has testing labs in Middleton, Wis., and Menlo Park, Calif., among others sites in the U.S. At Intertek, fire-resistance testing for steep-slope roofs is conducted using a “typical” roof as defined in the standard, which consists of 15/32-inch plywood (Spread of Flames) or 3/8-inch plywood (Burning Brand), 15-pound felt and Class A three-tab asphalt shingles. An alternate construction for the Spread of Flames test is to use any classified rolled asphalt membrane, mechanically secured over a non-combustible deck/material.

Low-slope roof testing has a slightly different construction, and the Spread of Flames test is the only test conducted. The low-slope roof consists of a 15/32-inch plywood substrate; 4 inches of polyisocyanurate insulation; and a single-ply, mechanically attached membrane. This membrane is required to have demonstrated a Class A fire rating. A typical membrane used for the testing is a 0.060-inch-thick EPDM roofing membrane.

Fire-resistance testing is just part of the rigorous testing criteria for PV modules; test requirements for the module’s power output, grounding, accelerated aging and conditioning, thermal cycling, UV exposure, and high humidity/freeze tests are also part of the performance testing process. To properly test and certify PV products for the solar market, third-party performance testing ensures independent verification of warranty claims, endurance, output, and functionality in a variety of climate or conditions.

ETL ListedProducts certified by Intertek will receive the ETL Listed Mark, which is required by the U.S. National Electrical Code for the sale of PV systems. Intertek certification provides assurance to roofing contractors, architects, and building owners that a product has not only been tested and met the necessary requirements, but also continues to do so even after installation. Further, Intertek’s ETL markings have long been recognized by regulatory bodies as a leading indicator of proof of conformance and quality for products throughout the U.S. and Canada. Code officials and inspectors, retailers and consumers across the U.S. accept the ETL Listed Mark as proof of product safety and quality. Today, the ETL Mark is the fastest-growing safety certification in North America and is featured on millions of products sold by major retailers and distributors every day.

PHOTOS: Intertek

Learn More

For more information about the testing and certification process, download Intertek’s free white paper: “Photovoltaic Panel and Module Fire Resistance Testing: Comprehensive Guide to ANSI/UL 1703” at Intertek.com/energy/photovoltaic.

MORE ABOUT INTERTEK

In December 2013, Intertek acquired York, Pa.-based Architectural Testing Inc. to become one of the world’s largest quality-solutions providers to the building and construction products’ industry worldwide. From code compliance, performance testing, product inspection, certification and building verification services, Intertek offers its customers everything needed to get their product to market quickly and efficiently by offering total solutions. With a total network of more than 1,000 laboratories and offices and more than 36,000 people in more than 100 countries, Intertek supports companies’ success in the global marketplace by helping customers to meet end users’ expectations for safety, sustainability, performance, integrity and desirability in virtually any market worldwide. For more information about Intertek’s building products’ business, visit Intertek.com/building.

From Screw-down to Standing-seam Metal Roofing

Time to reroof an old screw-down metal roof? Are you thinking about upgrading to a new standing-seam roof? Great idea! Today’s new standing-seam roofs are truly state-of-the-art; available in many profiles and finishes; and, more importantly, address many of the issues encountered in older generation screw-down metal roofs.

Caulk, roof coating and tar patches were used to cover leaking fasteners and panel end laps.

Caulk, roof coating and tar patches were used to cover leaking fasteners and panel end laps.

The screw-down metal roof and wall panel has been the backbone of the metal building industry since its inception and still represents a significant part of the total market. Screw-down panels are lightweight, durable, inexpensive and strong enough to span up to 5 feet between structural supports. Screw-down roofs and walls also have a wonderful physical property: The panels can and frequently are used as “diaphragm bracing,” securely holding the building’s roof purlins and wall girts in position, adding rigidity to the structure in much the same way drywall strengthens stud walls. This is a huge material—and labor—cost saver!

The early systems were not without problems, however; much of the technology we take for granted today did not exist in the early years of pre-engineered buildings. Many roofs during the late ’60s thru early ’80s were installed using 10-year life fasteners to secure a 30-plus-year life roof.

The fastener issue seems crazy today given the numerous inexpensive, long-life, weathertight, self-drilling screws available. Back when I started in the metal building industry, you could have the newly developed “self-drilling” cadmium fasteners or “self-tapping” stainless. Self-tapping meant you had to pre-drill a hole in the panel and purlin to install it—a much slower and more expensive process. Most of us used the less expensive but (unknown to us at the time) fairly short-life cadmium-coated fasteners and often never provided the option of a stainless upgrade to our customers.

Another shortcoming with screw-down roof panels is that, generally speaking, screw-down panels on metal buildings should be a maximum length of about 80 feet. Longer roof-panel runs frequently suffered rips or slots in the metal caused by expansion and contraction. Metal panels expand and contract at a rate of about 1 inch per 100 feet of panel run. This is normally absorbed by the back and forth rolling of the roof purlin and some panel bowing, but after 80 feet or so they can no longer absorb the movement resulting in trauma to the panels and trim. I have frequently seen this 80-foot limit exceeded.

a rusted fastener has caused the surrounding metal to corrode and fail.

A rusted fastener has caused the surrounding
metal to corrode and fail.

Standing-seam panels eliminate both of these shortcomings. The panels are attached to “sliding clips”. These clips are screwed to the purlins and seamed into the side laps of the panels securing them and thus the panels have very few, if any, exposed fasteners. The clips maintain a solid connection with the structure of the building while still allowing the panels, which can be 150 feet or longer, to move with expansion and contraction forces without damage.

This is great news for the building owner: You’re providing a more watertight roof, few if any penetrations, and expansion and contraction ability. It does come with a catch, however; standing-seam panels, because they move, do not provide diaphragm strength. The building’s roof purlins must have significantly more bridging and bracing to keep them in their correct and upright position. This is automatically taken care of in new building design but when it comes time to reroof an older building, removing the existing screw-down roof could remove the diaphragm bracing it once provided and make the building structurally unsound. Yes, that’s bad!

PHOTOS: ROOF HUGGER INC.

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Wind Loading on Rooftop Equipment

I recently attended a continuing-education conference for civil/structural engineers that discussed changes in the 2012 International Building Code (IBC) and the referenced ASCE 7-10 “Minimum Design Loads for Buildings and Other Structures”. During the seminar, the question was asked: “Who is responsible for the design of wind loading to rooftop equipment as defined in the IBC and Chapter 29 of ASCE 7-10?” The most accepted response was to add a section in the structural general notes that wind design on rooftop equipment is to be designed “by others”.

A structural engineer designed the metal support system and load transfer from the new HVAC unit down through the structure.

A structural engineer designed the metal support system and load transfer from the new
HVAC unit down through the structure.

The design requirements for wind loading on rooftop equipment have been included in previous editions of the IBC and ASCE 7, but significant changes have been included in ASCE 7-10. The increased attention is in part because of more severe wind events in recent years. While it is not the primary responsibility of the roofing consultant or contractor to evaluate the systems being placed on the roof, it is good to understand the code’s requirements for loading to rooftop equipment, how the load is determined and applied, and how the load is transferred to the building structure.

CODE REQUIREMENTS

The primary focus of the roofing professional in the IBC is concentrated on Chapter 15 (Roof Assemblies). While there are requirements in Chapter 15 addressing rooftop structures, these requirements, particularly in relation to wind loading, extend beyond Chapter 15. It is therefore imperative to be familiar with other sections of the code.

For instance, Section 1504 (Performance Requirements) refers the user multiple times to Chapter 16 (Structural Design) for wind-loading-design requirements. While roof manufacturers typically prequalify their systems based on various industry standards (ASTM, FM, ANSI, etc.), rooftop equipment supports are not typically prequalified because of the variability of placement and conditions. Similarly, new to this code cycle, Section 1509.7.1 includes the requirement for wind resistance for rooftop-mounted photovoltaic systems per Chapter 16 of the IBC. Other industries or trades have similar requirements. Section 301.15 of the 2012 International Mechanical Code and Section 301.10 of the 2012 Fuel and Gas Code require “equipment and supports that are exposed to wind shall be designed to resist the wind pressures in accordance with the IBC”.

Section 1609 of Chapter 16 (Wind Loads) applies to wind loading on every building or structure. Section 1609.1.1 provides two design options. The designer can use chapters 26 to 30 of ASCE 7-10 or Section 1609.6 of the IBC. Note however that Section 1609.6 is based on the design procedures used in Chapter 27 of ASCE 7-10, which does not address wind loading on rooftop equipment and thus is not applicable. Chapter 29 of ASCE 7-10 (Wind Loading on Other Structure and Building Appurtenances) contains the procedures used to determine wind loading on rooftop structures and equipment.

DETERMINING AND APPLYING WIND LOADING ON ROOFTOP EQUIPMENT

Properly specified ballasting blocks are designed and formed to better address the freeze/thaw cycle.

Properly specified ballasting blocks are designed and formed to better address the freeze/thaw cycle.


To determine wind loading on rooftop equipment, the first step is to identify the building Risk Category (formerly the Occupancy Category) and the building location. The Risk Category is determined from Section 1604.5 and Table 1604.5 of the IBC or Table 1.5-1 of ASCE 7-10. There are slight variations in the two codes but typically each will produce the same Risk Category.

The Risk Category and the location are then used to determine the design wind speed based on published wind-speed maps, available in Section 1609.3, figures 1609 A to C of the IBC, or Section 26.5.1, figures 26.5-1 A to C of ASCE 7-10. It can be difficult to read these maps to select the appropriate wind contour line, specifically along the East Coast. The Redwood City, Calif.-based Applied Technology Council (ATC), a non-profit that advances engineering applications for hazard mitigation, has digitized the maps providing a valuable resource for determining design wind speeds by GPS coordinates or the building’s address. Visit ATC’s wind-speed website. Note however that it is always advisable to cross check this design wind speed with the maps in the adopted code or with the local building authority.

PHOTOS: MIRO INDUSTRIES INC.

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