The thick and thin of fluid-applied air barriers

Durability and exposure
Some building envelope consultants have been concerned with the influx of newcomers in the FAAB market, requiring them to comply with various ASTM test procedures. In some cases, they have tested fluid-applied air barriers to ASTM D471, Standard Test Method for Rubber Property Effect of Liquids. This test is intended for rubber ([EPDM]) pond liners, not FAAB. The industry has been working on more applicable durability standards. One of these initiatives falls under ASTM Committee E06−Performance of Buildings.

The committee’s Work Group WK50742 is writing a new standard, Standard Practice for Assessing the Durability of Fluid-applied Air and Water-resistive Barriers. Katherine Wissink of engineering group Simpson Gumpertz Heger (SGH) presently chairs this work group. This proposed standard aims to develop test methods for FAAB that do not have an established track record. This proposed standard practice provides test methods and accelerated aging techniques used to assess the durability of these products.

“In most cases, fluid-applied air-barrier membranes serve as the primary air barrier and water-resistive barrier for the exterior wall system and, in some cases, serve as the vapor retarder depending on the vapor permeance of the membrane,” explained Wissink. “The integrity and continuity of the membrane is essential given that this single material may perform up to three important functions and is critical to the performance of the wall system in terms of moisture migration and waterproofing.”

Conclusion
Given the ever-expanding FAAB industry, it is critical all peripheral data is read and fully understood. Only then, can the designer be fully informed on what they are truly delivering to an owner. When it comes to deciding on a fluid-applied air barrier, it is evident physical properties and material and system performance are not equal. Just because a certain FAAB has passed certain requisite ASTM tests does not make it equivalent in regard to long-term durability, crack-bridging, and elongation.

Scott Wolff, CSI, CDT, is the Midwest building science manager at Henry Company, and has been in his current position for a decade. He has worked in an architectural capacity for 15 years within the industry and is active with the Chicago Chapter of the Building Enclosure Council (BEC). Wolff can be reached at swolff@henry.com.

Todd C. Skopic, CSI, CDT, LEED AP, is a building science manager at Henry. He has been in the air barrier industry for 16 years, working with different manufacturers. Skopic is active in BEC, RCI International, and ASTM, and serves on the Terminations and Flashing Committee for the Air Barrier Association of America (ABAA). He can be contacted via e-mail at tskopic@henry.com.

 To read a letter to the editor regarding this article, and the authors’ response, click here.
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