Hempcrete was approved for the model U.S. residential building code during a hearing last week overseen by the International Code Council (ICC), HempBuild Magazine reports. The material was approved as an appendix for the 2024 International Residential Code (IRC), which governs U.S. residential building codes for 49 out of 50 states.
The new code, set to be published formally in 2023, will feature Hemp-Lime (Hempcrete) under “Appendix BA.” Specifically, hempcrete was approved as a non-structural wall infill system similar to cob and straw bale construction, according to the report. The approval applies to one- and two-family dwellings and townhouses and should increase the availability of hemp-based building materials and facilitate greener construction projects around the U.S.
Hempcrete is a popular alternative to concrete that is made from a mixture of hemp stalk hurds and lime. It creates a fire-resistant fibrous insulation wall that also acts as a moisture regulator. Additionally, because it is made from hemp — an organic material — hempcrete is considered a carbon-sequestering construction material which further improves its sustainability.
The successful application to certify hempcrete for the IRC was submitted by the U.S. Hemp Building Association after having raised more than $50,000 and working alongside a committee of civil engineers, hemp-lime builders, architects, and other experts. CoExistBuild’s Ana Konopitskaya, a Pennsylvania-based architect who helped write the application, told HempBuild Magazine that “including hemplime” in U.S. residential construction codes was “of paramount importance.”
“It will allow architects like myself, focused on sustainability, to specify this product in any municipality across the U.S.” — Konopitskaya, via HempBuild Mag
While hempcrete will be available to most home construction projects in the U.S., it remains prohibited from commercial projects until at least 2025 — that is when officials are set to renew the International Building Code (IBC), which governs any occupancies not covered by the IRC.
The construction material has long been used in France and more recently in Canada but federal hemp prohibition in the U.S. kept it out of official building codes for decades despite its uniquely sustainable properties.
The U.S. legalized hemp at the national level in 2018.
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