Chapter twenty-three of the International Build Code (IBC) provides the minimum requirements for buildings and structures that use wood and wood-based products. The 2021 edition of the IBC added new test and performance requirements for fire-retardant-treated wood and the 2024 edition clarified these requirements. These new requirements are essential for manufacturers to understand and follow to ensure their products are safe and code-compliant.

New Performance Requirements – 2024 IBC Chapter 23
The 2021 IBC revised Section 2303.2 Fire-retardant-treated wood to require both a flame spread index of 25 or less and the flame front to not progress more than 10 ½ feet past the centerline of the burners throughout the test. Prior to this update, wood structural panels could either meet a flame spread index of 25 or demonstrate compliance through their flame front progression.

New Test Requirements – ASTM E84 and ASTM E2768
ASTM E84, one of the most common test methods in the building industry, determines the flame spread index and smoke developed index of building materials. The test method measures the relative burning behavior of materials by observing the flame spread and the smoke development compared against two control materials. Detailed information about the ASTM E84 test method and equipment is available here.

The new test requirements, originally added in the 2021 IBC, include extending the ASTM E84 test for an additional 20 minutes after the initial 10-minute test duration.
The 2024 IBC further added a new Section 2303.2.1 which permits ASTM E2768 as an alternate test method. ASTM E2768 is the extended duration surface burning characteristics test and is often referred to as an “extended ASTM E84” test. Unlike the 10-minute test duration in ASTM E84, testing in ASTM E2768 extends the total testing time to 30 minutes. Both test methods are commonly used to test coatings, fire-retardant materials or treatments, foam plastics, interior finish materials, paints, and plastics.

Another new requirement added in the 2021 IBC is the new Section 2303.2.3 (now Section 2303.2.4 under the 2024 IBC) which states that “wood structural panels shall be tested with a ripped or cut longitudinal gap of 1/8 inch”. However, ASTM E84 does not yet include mounting methods for wood structural panels to meet this new requirement. The ASTM committee responsible for ASTM E84, which includes participation across the building industry, is currently working to standardize the mounting methods to satisfy the code requirements. To ensure continued compliance for fire-retarded treated wood and coating manufacturers, ICC NTA and ICC-ES have jointly developed appropriate mounting methods to satisfy the 2024 IBC requirement for products certified by ICC-ES.

New Compliance Requirements = New Testing

With these substantial changes to the code, manufacturers of products that are required to comply with Chapter 23 of the 2024 IBC may need to conduct new testing of their products. Because the mounting methods are currently being worked through the appropriate processes, it will be important for manufacturers to reach out to their third-party partners, including test labs and certification bodies, to ensure the testing they complete will continue to satisfy the code requirements and updated standard requirements and avoid extraneous testing or retesting. For further information or assistance, please reach out to us online or by phone at (574) 773-7975.
ASTM E84-21a. ASTM, 2021.
ASTM E2768-11(2018). ASTM, 2018.
International Code Council. “2018 International Building Code.” ICC, Accessed 12/04/2023.
International Code Council. “2021 International Building Code.” ICC, Accessed 12/04/2023.
International Code Council. “2024 International Building Code.” ICC, Accessed 12/06/2023.