A new ASTM International test method aims to prevent air leakage in and around roofs, helping improve energy efficiency, reduce moisture problems and prevent pollutants from entering a building.
“It is critical that each assembly of the building envelope be investigated for air-leakage performance with appropriate standards,” says ASTM Member Sudhakar Molleti. “What cannot be captured in the material and full envelope air leakage testing—the structural strength and continuity of the air barrier assembly—can be quantified in the assembly testing. To achieve energy efficiency of building and to adapt for climate change, comprehensive data of material, assembly, and full envelope air leakage testing are needed. By quantifying air leakage in roof assemblies, this new standard can serve as a platform for supporting code compliance and for constructing energy-efficient and sustainable roof assemblies.”
Molleti, a research officer with more than 10 years of roof assembly testing at the National Research Council Canada, Ottawa, notes roofing membranes are air impermeable but can be compromised by factors, such as lack of continuity of the membrane seams, improper detailing around rooftop preparations, improper selection of flashing materials and improper connection of roof membranes to the exterior wall barrier.
Specifically, this new test method is a laboratory technique to determine air leakage in low-slope membrane roof assemblies and accounts for the wind fatigue expected during the life span of a roof by simulating negative air-pressure differences.
The new standard (soon to be published as D8052/D0852M, “Test Method for Quantification of Air Leakage in Low Sloped Membrane Roof Assemblies”) was developed by ASTM’s committee on roofing and waterproofing (D08).
In other news, a set of proposed ASTM International test methods will help support the growing number of roofing projects that use liquid-applied polymers. The proposed standard (WK40123, “Test Methods for Sampling and Testing Liquid Applied Polymeric Roofing and Waterproofing Membranes that Are Directly Exposed to Weather”) will help manufacturers; testing labs; and the construction industry as they sample, test and compare products. It is being developed by ASTM’s committee on roofing and waterproofing (D08).
The proposed standard includes ways to test liquid-applied polymeric materials that are cured to form roofing and waterproofing membranes that are directly exposed to all kinds of weather. By their nature, these materials are seamless. They are also useful when working with complex surfaces and custom-fit projects.
ASTM Member Philip Moser notes these membranes have been traditionally used for waterproofing of elevated parking decks, but their use for applications like roofing is quickly rising. Moser, a senior project manager specializing in building technology at Boston-based Simpson Gumpertz & Heger Inc., says, “Delivery to the exact point of application in relatively small containers makes these products particularly attractive for small rooftop terraces, congested urban areas and roofs that are not accessible by crane where delivery of larger containers would create logistical problems.”
The test methods would be used by manufacturers and testing labs, as well as the people who write specifications that indicate which test methods should be used to evaluate physical properties.
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