An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to www.epa.gov. This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Under the Asbestos Hazard Emergency Response Act (AHERA), when acquiring samples of multi-layered material such as wallboard, do you sample both the wallboard and the joint compound as separate materials or can you take a weighted average of both?

As stated in the January 5, 1994 Asbestos Sampling Bulletin clarification, joint compound and wallboard form a “wall system,” and the Environmental Protection Agency (EPA) therefore recommends the use of a composite analysis for this material. See 59 FR 542; see also 60 FR 65243 (1995). For joint compound (not skim coat), EPA recommends that an accredited inspector take a weighted average of the different wall system components to arrive at the final reportable number.