Hempcrete is now part of the 2024 International Residential Code’s Appendix BL—meaning homeowners can now legally build with hemp‑lime walls in 48 states.

In a landmark move, the International Code Council (ICC) included Appendix BL: Hemp‑Lime (Hennepbeton) Construction (see below) in de 2024 International Residential Code (IRC)—used by nearly 48 states as the model building code for single‑family and townhome construction. Although appendix adoption is voluntary, it means hempcrete is no longer an “alternative method” requiring costly permit approvals—it’s now mainstreamed in model codebooks.

Hennep builders and code experts hailed the inclusion as the result of years of effort by the US Hemp Building Association and volunteers, architects, and engineers. Hempcrete—made from hemp hurds mixed with lime or pozzolans—is lightweight, ademend, mold-resistant, carbon-sequestering, and offers excellent thermal and acoustic insulation—even though it isn’t structural on its own.

What this means: architects and developers now have clear code language that simplifies permit reviews for hemp-based walls—leading to wider adoption in eco homes, zero-carbon construction, and retrofit projects. States adopting the 2024 IRC are moving through a three‑year adoption cycle—meaning many will have hemp‑lime approved locally by as early as late 2025.

Industry experts see a domino effect: materials suppliers ramping up hurd production, builders training crews, and green building firms marketing hemp homes. Once limited to small custom builds, hempcrete now has the potential for scalable, modular housing or niche mid-size multi-family projects (though commercial code adoption under IBC lies ahead in 2025 submissions.

Appendix BL contains requirements for hemp-lime construction. Hemp-lime, commonly referred to as hempcrete, is a nonstructural, biocomposite insulation infill material composed of hemp hurd and a lime-based binder. The benefits of hemp-lime include high thermal performance, low embodied carbon emissions in production, high carbon sequestration in service, healthy living environments and high fire-resistance. These benefits, along with the 2018 United States legalization of hemp as a commercial crop, are driving rapid growth in interest and projects across the US.