Weathering the Storm
The Tests and Standards to Get You There
by Ken Brenden
As if this spring’s outbreak of destructive and deadly tornadoes
wasn’t enough, we now move into the 2011 hurricane season (June – November),
which some predict will be more severe than normal with strong odds of
at least one major (Category 3, 4, or 5) hurricane hitting a U.S. coastline.
For our industry’s part, we are well aware of the threat. Special attention
to window hurricane hazards began in earnest after the legendary Hurricane
Andrew in 1992. Stronger codes and test methods for assessing structural
resistance to high wind pressures and resistance to impact from windborne
debris ensued, such as ASTM E 1886 and E 1996, AAMA 506-08, Voluntary
Specifications for Impact and Cycle Testing of Fenestration Products,
and Miami-Dade TAS-201 and TAS-203.
Attention more recently has focused on water leakage driven by high wind.
Following the destructive 2004 hurricane season, the Florida Building
Commission sought out AAMA’s Southeast Region organization to assess current
test methods and develop a standard for testing windows’ ability to mitigate
water penetration damage under hurricane conditions. AAMA conducted a
12-month review and evaluation of existing test protocols and their ability
to address the cyclical nature of indoor-outdoor pressure differentials
and turbulent flow characteristics of real-world hurricane winds. The
effort culminated in the development of AAMA 520-09, Voluntary Specification
for Rating the Severe Wind-Driven Rain Resistance of Windows, Doors and
AAMA 520 provides an optional rating scheme for the ability of fenestration
products to resist severe wind-driven rain, based on ASTM E 2268-04, Standard
Test Method for Water Penetration of Exterior Windows, Skylights and Doors
by Rapid Pulsed Air Pressure Difference. Under this test method, water
is sprayed uniformly across the whole surface of the test specimen at
the rate of five gallons/square-foot/hour, impelled by simulated wind
pressure pulses that vary in rapid cycles for a total duration of 300
cycles. As the maximum applied pressure behind the spray increases from
5 to 14 psf, defining the ten performance level ratings, the total accumulated
leakage cannot exceed 15 ml per meter of sill width.
AAMA 520 continues to evolve based on ongoing research efforts. For example,
the AAMA Southeast technical committee is developing an addendum intended
to provide guidance to laboratories regarding water collection and measurement
techniques and potential rounding discrepancies between measured and calculated
Beyond writing its own standards, AAMA also has been a long-time supporter
of the work being led by Dr. Forrest Masters at the University of Florida,
including the 130 mph hurricane simulator at the University’s Wind Engineering
Lab in Gainesville. The simulator is capable of mimicking the actual pressure
pulses and lateral turbulence of a hurricane while dousing the test subject
with the equivalent of an 8-inch-per-hour rainfall.
Another facility working on analyzing the effects of hurricane-force storms
is the Institute for Business and Home Safety’s (IBHS) laboratory near
Charlotte, N.C. This facility can test and compare two full-size houses
built to different code requirements simultaneously by simulating up to
140 mph winds and rain.
align with aspects of the research goals of the IBHS and we are looking
into more ways to collaborate in the future."
AAMA’s interests align with aspects of the research goals
of the IBHS and we are looking into more ways to collaborate in the future.
Tornadoes: A Former Gap
AAMA just released AAMA 512-11, Voluntary Specifications for Tornado Hazard
Mitigating Fenestration Products, which provides a system for rating the
ability of windows to withstand tornadic impact, pressure cycling and
water penetration effects associated with a designed event. And, we will
continue to work collaboratively in researching and developing standards
relating to product performance under severe storm conditions.
Ken Brenden serves as technical services manager
for the American Architectural Manufacturers Association in Schaumburg,
Ill. He may be reached at email@example.com.
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No reproduction of any type without expressed written permission.