2027 Building Codes Finalized: Big Changes Ahead for Off-Site Construction and Flood Resistance

The International Code Council (ICC) recently released the final results of the Public Comment Hearings and Online Governmental Consensus Vote. This marks the final stage of the 2024-2026 code development cycle leading to the 2027 International Building Code (IBC), International Residential Code (IRC) and the other 2027 I-Codes.

NAHB Construction Codes & Standards staff and members of NAHB’s Construction Codes & Standards Committee testified at all stages of the process. NAHB members served on most of the code development committees, including the key committees for the IRC.

A new feature of this cycle is the “three strikes rule,” where a proposal disapproved at both committee action hearings and the public comment hearing does not go to the final vote. NAHB supported this change; it addressed our significant concerns with the 2021 IECC, where the online vote overturned multiple proposals that were disapproved during the hearings.

Significant proposals opposed by NAHB and disapproved under the new rule included expanded construction documents and under-slab vapor retarder requirements for the IRC and more stringent International Wildland-Urban Interface Code (IWUIC) requirements based on California’s wildfire mitigation provisions.

NAHB had an overall success rate of 85% obtaining its desired outcomes on proposals affecting the residential construction industry. Despite this success rate, a few significant changes opposed by NAHB were approved for the 2027 I-codes including:

• Expanding flood-resistant design requirements in the IBC and IRC to the 500-year floodplain and 500-year flood elevation.
• Requiring natural light be provided in multifamily dwelling units where living, dining and sleeping rooms have a floor area of 70 square feet or more.
• Expanding the scope of the International Fire Code (IFC) to cover energy storage systems installed in dwellings within the scope of the IRC.

Significant wins from the public comment hearings and online governmental consensus vote included:

• Approval of IBC and IRC proposals referencing the ICC 1200, 1205 and 1210 standards for off-site construction, providing uniform construction and inspection requirements for modular homes and buildings.
• Approval of IBC and IRC proposals provisions to allow the re-use of salvaged lumber for structural purposes if evaluated by a certified lumber grader.
• Disapproval of an IWUIC proposal from California for the highest-risk wildfire hazard areas that was approved during the 2024 committee hearings but disapproved at the recent public comment hearings.
• Disapproval of an IWUIC proposal to require submission of fire protection plans prepared by a registered design professional or an approved landscape architect or fire safety specialist.

The 2027 I-Codes will be published in stages over the rest of 2026 and early 2027, with the IBC, IFC and IWUIC anticipated in September 2026 and the IRC in February 2027. NAHB will provide a 2027 I-Codes Adoption Toolkit, including lists of significant changes, cost analyses and recommended amendments for our members to use during state and local code adoption processes. See adoption kits for all the residential building codes.