ICC News Release
For Immediate Release
Revised Acceptance Criteria for Spray-Applied Foam Insulation in Unvented Attics Unanimously Approved

AC377 will provide clarity for code officials and streamlined compliance for manufacturers and industry partners

Brea, CA – During the February 2023 ICC-ES Evaluation Committee public hearing, a revision to ICC-ES acceptance criteria (AC377) for spray-applied foam plastic insulation was unanimously approved.

The revision to AC377 provides a clear, concise and transparent path for spray-applied foam plastic insulation for use in unvented attics without a code-prescribed ignition barrier. The revision was developed with product manufacturers and industry partners and will provide code officials clarity in the alternative test method specifically for use in unvented attics.

ICC-ES and ICC NTA conducted research testing to determine the performance characteristics of code-compliant unvented attic insulation materials, and with which performance characteristics were used as the basis for the conditions of the approved revision to AC377.

The alternative test option provided through the revision allows spray-applied foam plastic insulation that may have not met the requirements of AC377 previously, but under the specific configuration and testing of an unvented attic with a downward opening (Appendix U), manufacturers can avoid seeking costly special approval processes in order to use an alternate test procedure to the previous AC377.

“The approval of Appendix U in AC377 is an excellent example of the ability of ICC-ES to provide total conformity assessment solutions (testing, inspection and certification) to product manufacturers in order to improve building safety as well as develop new and pioneering evaluation methods for innovative products,” said Eric Polzin, ICC-ES Senior Staff Engineer.

In addition to the new pathway for use in unvented attics, ICC-ES and industry representatives have also elected to include a new requirement, the inclusion of installation certificates geared towards increasing safety by providing clear instructions to building occupants and maintenance workers as to what safety considerations and use limitations are required for these spaces.

This revision to AC377 is a significant step forward in ensuring the safety and efficiency of unvented attics with spray-applied foam plastic insulation. It will provide a more streamlined process for manufacturers seeking to comply with the relevant codes and regulations.

ICC-ES Acceptance Criteria establish technical requirements for the issuance of ICC-ES evaluation reports, which are intended for use by code officials and design professionals in determining product compliance with applicable codes.

Click to learn more about ICC-ES Acceptance Criteria development.

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About ICC-ES

A nonprofit, limited liability company, ICC-ES is the United States’ leading evaluation service for innovative building materials, components and systems. ICC-ES Evaluation Reports (ESRs), Building Product Listings and PMG Listings provide evidence that products and systems meet requirements of codes and technical standards. The ICC-ES Environmental Programs issue VAR environmental reports that verify a product meets specific sustainability targets defined by today’s codes, standards, green rating systems and ICC-ES environmental criteria. ICC-ES is a member of the ICC family of solutions.

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