September 2008 I
B
S e v e r e W i i n d D r i i v e n R a i i n R e s s i i s s t t a n c e
This Informational Bulletin provides a general overview of a new AAMA specification known as AAMA 520, which is undergoing a year long technical review and evaluation period. The document is scheduled for release prior to the 2009
Hurricane Season.
What is AAMA 520?
AAMA 520 is entitled, Voluntary
Specification for Rating the Severe Wind
Driven Rain Resistance of Windows, Doors and Unit Skylights . The development of this specification was authorized by the AAMA
Board and overseen by the AAMA
Southeast Region's technical committee.
The purpose of the voluntary document is to provide a standard test method for evaluating and rating the performance of fenestration products subjected to “severe wind driven rain conditions.”
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The History Behind the Effort
The 2004 hurricane season was a record setting year in terms of presidential disaster declarations. President Bush issued 68 disaster declarations, 27 were due to hurricanes; according to FEMA report 490.
The insurance industry stated that hurricanes
Charley, Frances, Ivan and Jeanne resulted in a financial impact in excess of 20 billion dollars. FEMA's report stated, “The performance of building envelope systems in high wind events requires attention.”
Figure 1: How do test standards measure up?
Figure 2: The Outer Band of Hurricane Charlie
What's the Issue?
While windows and doors; at least those which have been tested to meet impact resistance, fared well in terms of structural performance, there were reportedly numerous complaints regarding uncontrolled water penetration at and around these products (see Figure 3).

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September 2008
Severe Wind Driven Rain Resistance
Based on these complaints, and subsequent discussions with the Florida Building
Commission, AAMA's SE Technical
Committee took on the challenge of reviewing the existing water penetration testing protocols with the intent of establishing more realistic water performance standards for hurricane coastal areas.
Figure 3: Water damage around windows is often falsely attributed to window leakage.
The current industry standard requires windows and doors to resist water penetration at 15 or 20% of the rated design pressure using static pressure test methods.
While these test methods may be appropriate for most inland areas of the U.S. it seems appropriate to review the current test methods and available research data to determine if there are other procedures that may be more representative of the severe conditions found in coastal areas.
Review and Comparison of Test Methods
Several test methods were studied during the
AAMA research period including, the
Japanese (JIS A 1517), Australian (AS/NZS
4282:1985), ASTM E 331, E 547 and
E 2268, and AAMA's 501.1.
The AAMA certification program utilizes
ASTM E 331 and E 547, two longstanding standards for water penetration. These standards use static pressure to simulate
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Page 2 of 3 wind driven rain, however they do not replicate wind gusts or pulsating wind. The
AAMA 501.1 dynamic test utilizes a wind generator to create pulsating winds, but there are some pressure limits due to the equipment used.
The Japanese and Australian water test methods attempt to simulate gusting effects by rapid pulsation of the static pressure.
These methods were considered by some to be a “step up” from the current ASTM methods used. ASTM most recently developed ASTM E 2268, Standard Test
Method for Water Penetration of Exterior
Windows, Skylights, and Doors by Rapid
Pulsed Air Pressure Difference , which is similar to the aforementioned international test methods in terms of creating rapid pressure pulsation.
Details of AAMA 520
The new AAMA 520 specification establishes 10 different levels of performance utilizing the ASTM E 2268 test method. Each of the established performance levels include both an upper and lower pressure limit (e.g, level 1 includes a 5 psf lower limit and a 15 psf upper pressure limit, with 7.5 psf being the mean).
After going through a set of five operation cycles (for operable windows) and a sixty second pre-load pressure test (equal to the pre-established upper limit water test pressure value), the specimen may then be tested to determine the water resistance performance level.
During the test, water is sprayed uniformly across the specimen at the standard rate of 5 gallons per square foot, per hour. With the water spray on, the rapid pulsating pressure is applied in accordance with ASTM
E 2268. The specimen is exposed to 300 pressure cycles that range from the established low pressure to the high pressure. Each pressure cycle last

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September 2008
Severe Wind Driven Rain Resistance approximately 2 seconds, which results in about a 10 minute water test.
Round One of Testing is Complete
SE AAMA contracted with Architectural
Testing to perform research testing on three sliding glass door specimens using ASTM
E 331, ASTM E 2268 and AAMA 501.1 test methods. This research testing produced some very interesting results. One commercial specimen was able to achieve a
Level 6 performance, involving 10, 20, and
30 psf pressure levels. This was attained during the 300 pressure cycles when tested in accordance with ASTM E 2268 – with no water leakage. This same specimen met a
15 psf water test pressure using the AAMA
501.1 dynamic test method. On the residential side, a modified unit was able to meet similar levels stated above after the application of a sill extender.
This is not to say that all products will be able to meet these new water test protocols, but it is possible that some will! Another important factor is that right now the intent is to allow some minor water penetration during the test; after all it is a hurricane.
The current specification allows for 15ml of water for each meter of sill length. This really changes things.
Code Adoption?
This is not quite ready for “Prime Time” just yet. Essentially, this standard provides a
“stake in the ground” for manufacturers and designers to evaluate new products and product enhancements.
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The voluntary specification, according to
AAMA, “will serve as an elevated performance characterization, but it is not intended for AAMA to submit this optional test for any building code adoption and enforcement”.
Now is the Time to Evaluate
Now is the time for all manufacturers to evaluate their coastal product lines per this new procedure.
During the review period, manufacturers would be well advised to test their products to see how they will fare. If you would like to test your product(s) to this new standard please contact any of our regional laboratories.
Need More Information?
The purpose of this ATI Informational
Bulletin is to introduce this new test specification and invite you to participate in the study. The information contained herein is not manufacturer or product specific and is provided as advisory information to our customers.
As always, the professional staff at
Architectural Testing is available to answer any questions or concerns.
Contact us if you would like to request a reprint of this article.
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