Specify Performance-Inspired Edge Systems
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| |  Wind Resistance Begins
at the Edge
By Amy Stokes
As we head into the heart of the 2007 storm season, I am reminded of the annual barrage of photos flashed across television screens and news papers depicting the countless damage inflicted by storms all across the nation. Hurricane season is a harsh reminder that vulnerabilities in the design, manufacture and installation of roofing systems carry a high cost. But hurricanes are not the only high wind events that threaten roofs, and no area of the country is exempt from wind-related roofing damage.
FEMA has divided the United States into four zones that reflect the number and strength of extreme windstorms encountered in these regions. These maps illustrate that, even if your building is not in the direct path of a potential hurricane, 40 years of tornadic and windstorm history across our dynamic nation teaches us that any roof in any place at any time may be called upon to protect the building below and the contents within from devastating winds.
In recent years, codes and standards have evolved in response to evaluations of roof performance during some noteworthy storms. Organizations such as ANSI/SPRI, RICOWI, and FM Global have led the charge toward improving how roofing systems are designed, manufactured and installed in hopes of preventing the kind of storm devastation our country has seen in the past 15 years. |  |  |
Last year, the Roofing Industry Committee on Weather Issues (RICOWI) released its investigative report of the damage caused by Hurricanes Charley (August 13, 2004) and Ivan (September 16, 2004). The goal of this initiative is “to perform unbiased, detailed investigations by credible personnel from the roofing industry, the insurance industry, and academia. Data from these investigations will, it is hoped, lead to overall improvement in roofing system durability and a reduction in insured losses, which may lead to lower overall costs to the public.”
  The RICOWI report states “the mode of initial damage was typically related to perimeter edge flashing,” and that “most damage was related to perimeter problems.”
The frequency of roof perimeter damage found during RICOWI’s investigation clearly supports conservative estimates from organizations such as Factory Mutual (FM) Global, that 75 percent of all wind-related roofing failures are attributed to insufficient or poorly installed perimeter metals. RICOWI Investigators recommended that roof perimeters should be designed and installed following roof material manufacturers’ recommendations in accordance with high-wind design guidelines such as ASCE-7 and ANSI/SPRI ES-1.
ANSI/SPRI ES-1 is acknowledged as the most important standard for roof edge performance, and is incorporated into the 2003 (and subsequent) International Building Code (IBC). The ANSI/SPRI ES-1 standard is comprised of three tests: RE-1 Test to failure – failure occurs when the membrane detaches from the edge termination, or the termination detaches from its mounting Static test with 100-pound load every foot used for ballasted systems; a calculation based on fastener placement is used for mechanically attached systems Membrane is pulled at a 45-degree angle to the roof deck to simulate billowing
RE-2 Test to failure - securement loss of any component of the roof edge system, or deformation that would hinder weather protection at the edge Incremental load applied to fascia and held for at least 60 seconds, then removed and increased in increments of 25 psf until 150 psf, then increments of 10 psf are applied
RE-3 Test to failure - securement loss of any component of the roof edge system, or deformation that would hinder weather protection at the edge Incrementally loads are applies as with the RE-2 test Simultaneous loads applied to face and top (back leg and top for one sample, front leg and top for another). The lowest test results are used.
Codes and standards aside, it is incumbent upon designers, manufacturers and installers to provide performance-inspired roofing and edge systems to our customers who depend on our expertise. Designers bear the burden of specifying products that will perform as needed when needed, and comply with ANSI/SPRI ES-1. Contractors are responsible for correctly procuring and installing those systems. And, in addition to fabricating fully tested metal edge systems, manufacturers must be prepared to support designers and installers with guidance and instruction, and to provide a Certificate of ANSI/SPRI ES-1 Compliance for each project. | 
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