In June 2025, the City of Phoenix, AZ adopted the 2024 International Residential Code (IRC) along with a handful of natural-building appendices including Appendix BL, Hemp Lime (Hempcrete) Construction. But as far as anyone in the hemp building industry can tell, it went largely unreported.

A group of natural building code experts and building pros submitted updates this summer to the US residential model codes that will make it cheaper and simpler to build with hemp-lime (“hempcrete”). An online fundraiser seeks to raise $12,000 to fund the updates to the 2027 International Residential Code (IRC) that will include ASTM tested 1-hour fire-resistance rated walls.

Minnesota appears to be the first US state on the path to adopting the newest official residential building codes featuring plant-based building materials after a July 15 hearing in St. Paul.