Hempcrete takes ‘important step’ in U.S. by entering international code

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Hemp building stakeholders in the U.S. say they are putting the finishing touches on documentation that will enshrine hempcrete as an approved building material for residential structures under the International Code Council (ICC).

The ICC last September accepted an appendix governing the use of hemp-lime mixtures as a non-load-bearing building material and wall infill system into the 2024 International Residential Code (IRC). The last stage in the ICC process is completing official commentary that explains the code language, said Jacob Waddell, president of the Hemp Building Institute (HBI), a non-profit organization leading that effort.

Guiding professionals

“This is an important step on a journey to making hempcrete an option for widespread adoption in the construction industry,” Waddell said. “Professionals in the construction industry now have a guide to what is required to build with hempcrete, and educational material can be developed to spread the requirements of the code.”

Appendices in the IRC are essentially model codes that local jurisdictions may adopt. The IRC sets minimum standards for one- and two-family dwellings and townhouses. The guidelines, which serve as the basis for the residential building code in all U.S. states except Wisconsin, are founded on broad principles that make both new materials and new building designs possible. The ICC’s codes are primarily used in the United States, but some other countries also adopt them.

Where local building authorities adopt the IRC standards, architects and builders can specify the material in building permit applications.

Scope of code

The ICC’s model codes, which are regularly updated, cover building safety issues related to design and construction, fire safety, plumbing, mechanical systems, and energy efficiency. Building and safety experts across North America contribute expertise to development of the Council’s code. ICC committee voting members work for government health and safety agencies. 

The IRC hempcrete appendix addresses the use of hemp-lime mixtures in regions of low seismic risk without engineering. Buildings in high risk areas require an engineered design.

The original application for certifying hempcrete for the IRC was submitted last year by the U.S. Hemp Building Association, which raised more than $50,000 to develop the appendix. The Hemp Building Institute is now looking to raise an additional $20,000 to complete the explanatory commentary, intended to clarify “any potential misunderstandings and to expand the readers’ understanding on known alternatives that may not have made it into the code,” HBI said in a press release.

Path to growth

The commentary will include a clarification that hempcrete can also be used in ceiling and flooring applications in addition to wall systems, and other supplementary explanations, HBI said.

Stakeholders have said including hempcrete in U.S. building codes can widen the path for projects based on the material and be a catalyst for expanding the residential hemp building sector overall.

Waddell said HBI also has a plan to qualify hempcrete for commercial buildings through the model International Building Code (IBC), which governs buildings not covered by the IRC. The IBC is renewed every three years and will be open for submissions in 2025.

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