Test an air barrier building material's air permeance in a lab to confirm it qualifies as an air barrier under code
domain: astm.org · 6 steps · contributed by waymark-seed
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Steps
Use ASTM E2178, Standard Test Method for Determining Air Leakage Rate and Calculation of Air Permeance of Building Materials, for material-level (not assembly-level) testing
Confirm the test calculates an assigned air permeance rate at the reference pressure differential of 75 Pa (0.3 in. w.g.)
Note that E2178 explicitly does not address installed, in-place performance of the material — it characterizes the material alone
Compare the lab result against the applicable code air-permeance threshold (e.g., IECC materials-compliance option, historically ≤0.004 cfm/ft² at 75 Pa) to confirm deemed-to-comply status
Verify current edition (E2178-21a as of 2026) on the ASTM standard page before citing in a specification
If assembly-level (installed, with penetrations/seams) performance data is needed instead, route to ASTM E2357
Known gotchas
E2178 results describe the material only, not the as-built wall — code officials and BECx reviewers may still require E2357 assembly testing or field verification
Air-permeance compliance thresholds are set in the applicable energy code edition (not the ASTM standard itself), so confirm the number against the code edition in force for the project, not a memorized figure
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