commentNew Standard Puts Air Barriers to the Test
“Build tight and ventilate right” is a favorite motto of building scientists concerned with good indoor air quality and low energy use. A new test method from ASTM International—ASTM E2357, Standard Test Method for Determining Air Leakage of Air Barrier Assemblies—offers them help in living up to their motto.
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The method provides the first uniform way to evaluate leakage through an air barrier as part of an actual wall assembly. According to Lance Robeson, AIA, president of Building Envelope Technologies, a founder of the American Air Barrier Association, and the principal author of the standard, before this standard existed, the only way to evaluate the performance of an air barrier was to evaluate the performance of the constituent materials. “This standard is designed to test a number of materials combined into a system,” Robeson said.
The test simulates real-world conditions by calling for the assembly of an 8-foot-by-8-foot mockup of an exterior wall. The mockup includes a tie-in to a foundation wall, a tie-in to a roof, duct and pipe penetrations, outlet penetrations, a window, and brick ties, all of which must be addressed by the air-barrier system. The assembly is tested before and after exposure to sustained wind and wind gusts, which are adjusted to exert both positive and negative pressure on the assembly.
Grace Construction Products recently became the first manufacturer to use the standard, announcing in July 2007 that its Perm-A-Barrier air barriers—including wall membrane, fluid-applied, and vapor-permeable products—had passed laboratory tests with leakage of less than 0.0008 cubic feet per minute per square foot. Robeson said he expected other manufacturers to follow suit but argued that the standard’s greatest use will be in testing onsite mockups of wall assemblies for high-performance commercial building projects, where materials as well as construction methods need to be evaluated. Robeson also noted that several additional air-barrier standards are in the works, including one testing multiple assemblies at once—essentially simulating the performance of whole buildings.
For more information:
Air Barrier Association of America
Walpole, Massachusetts
866-956-5888
www.airbarrier.org
ASTM International
West Conshohocken, Pennsylvania
610-832-9585
www.astm.org
This article was produced by BuildingGreen, Inc.- www.buildinggreen.com
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