Hemp-lime (hempcrete) construction in US residential building codes took a major step forward in Cleveland last week when proposed updates to Appendix BL of the 2027 International Residential Code (IRC) were unanimously approved during the International Code Council (ICC) Committee Week proceedings. An online fundraiser successfully raised more than $12,000 to pay for the code adoption.

At the 2025 Rocky Mountain Natural Building Conference in Bozeman, Montana, last week, three leaders in hemp-based construction shared their perspectives on the material’s future: Greg Wilson of HempWood, Matt Marino of Homeland Hempcrete, and architect April Magill of Root Down Building Collective. (Full disclosure: I serve as executive director of the conference hosts, the Colorado-based Natural Building Alliance.)

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.

Hemp building materials were officially approved in the model US residential building code at a Louisville, KY public hearing overseen by the International Code Council (ICC) last week.