Appendix BJ and Appendix BL sometimes reference sections of the IRC, so access to the complete IRC is important for full understanding and full use. The IRC applies to one and two-family dwellings, their accessory structures and townhouses. The IRC is a model code with no legal standing of its own, but it is the basis for the residential code in virtually every state and local jurisdiction in the United States. However, many jurisdictions have not yet adopted the 2024 IRC, and some may not adopt Appendix BJ or Appendix BI. Jurisdictions that do adopt Appendix BJ may also amend it. Consult your local building department to understand which edition of the IRC is the basis for its current building code and whether Appendix BJ is included. Project applicants who wish to use Appendix BJ or Appendix BI for a project where the state or local jurisdiction has not adopted the 2024 IRC or the Appendix, can propose their use on a project basis with the local building official. The Commentary describes intent, and gives compliance examples for the Appendix code requirements. This is especially helpful for design professionals, builders, building owners, and code officials with little or no experience with strawbale or light straw-clay construction. Appendix BJ and California: Appendix BJ from the 2024 IRC is included in the 2025 California Residential Code (CRC) and was adopted by the Department of Housing and Community Development (HCD) for mandatory statewide use. The 2025 CRC took effect January 1, 2026 for permit applications dated Jan. 1, 2026 through Dec 31, 2028. If a local building department or official claims their jurisdiction did not adopt Appendix BJ or otherwise refuse to use it, please contact Martin Hammer. Questions or Comments about codes can be directed to their lead author, Martin Hammer at mfhammer@pacbell.net .