WUI Fire Testing Justify Hardening Methods

AWC continues to battle efforts to ban building materials in wildland urban interface (WUI) zones through the use of data to demonstrate that a performance-based approach using widely recognized testing protocols supports the fire resistance of wood structures. AWC performed four fire tests at the Western Fire Center in Kelso, Washington, using a modified version of the ASTM E2957 test exposure. The tests resulted in key data that AWC and the industry used to address concerns raised in WUI codes and standards development activities, preventing unfair exclusion of wood products in certain WUI-designated areas.

Based on the results of these tests, AWC believes that the ASTM E2957 test method, with slight modifications, can be used to evaluate designs of the soffit hardening and intersections between the exterior wall and the soffit. As a result, AWC staff has submitted recommendations to reference ASTM E2957, with modifications, in the new ICC 605 Standard for Residential Construction in Regions with Wildfire Hazard to address conditions where the defensible space is not maintained, and the exterior wall/soffit can be exposed to direct flame impingement.

This testing directly supports AWC efforts in codes and standards development; specifically, it has supported AWC’s advocacy in the new ICC 605 standard and the new California WUI code, which is expected to be effective in 2026. Leading with data-driven results has opened doors to help AWC directly demonstrate the safety and resiliency of our industry’s products while advocating for favorable code requirements and standards. These efforts will become increasingly important as AWC looks ahead to 2025 and the increased attention paid to WUI construction following the devastating Los Angeles fires.