Specify Performance-Inspired Edge
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Tucker, Georgia 30084
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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.
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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. |
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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:
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RE-1
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Test to failure – failure occurs when the membrane detaches from the
edge termination, or the termination detaches from its mounting
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Static test with 100-pound load every foot used for ballasted systems;
a calculation based on fastener placement is used for mechanically
attached systems
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Membrane is pulled at a 45-degree angle to the roof deck to simulate
billowing
RE-2
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Test to failure - securement loss of any component of the roof edge
system, or deformation that would hinder weather protection at the edge
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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
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Test to failure - securement loss of any component of the roof edge
system, or deformation that would hinder weather protection at the edge
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Incrementally loads are applies as with the RE-2 test
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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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© 2007 IMETCO (Innovative Metals Company, Inc.) |
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Neither Innovative Metals Company, Inc. (IMETCO) nor any of its affiliates
makes any representation or warranty of any kind with respect to the
materials and information contained herein. Although IMETCO attempts to
provide accurate information, this bulletin is intended for general
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