American homeowners will soon be able to replace environmentally-unfriendly insulation with sustainable hempcrete, thanks to a new amendment to international building codes.
Hempcrete, which is made from mixing natural hemp fibers with lime, is a natural, carbon-sequestering material that can provide a fire-resistant, mold-proof alternative to traditional plastic-based insulation. European contractors have been building houses with hempcrete for nearly 30 years now, but US cannabis prohibition laws have prevented this natural insulation from appearing in American homes until recently.
“Hempcrete, a mixture of hemp hurds or 'shiv' (made from hemp stalks) and a lime binder, creates a long-lasting fibrous insulation for wall assemblies that is reusable, vapor permeable, stores carbon, resists fire, resists mold and resists pests,” the US Hemp Building Association (USHBA) explained in a press release. “Because hemp sequesters carbon in the walls of a building, hempcrete is an excellent building material that can offset the construction industry’s carbon footprint.”
The US finally legalized hemp in 2018, paving the way for the creation of hemp-derived building materials, weed packaging, bioplastics, and more. Last year, the USHBA submitted an application to the International Code Council (ICC) requesting that US building codes be amended to allow the use of hempcrete. The association raised over $50,000 and assembled a committee of civil engineers, hemp builders, architects, and code experts to advocate for their cause.
Last week, the ICC agreed to update its International Residential Code (IRC) to authorize the use of hempcrete as an approved wall infill. The IRC establishes building guidelines for one- and two-family residential homes and townhouses in every US state, with the exception of Wisconsin. The new building codes won't officially take effect until 2024, but contractors can apply with local building departments on a case-by-case basis to begin using hemp insulation before that date.
"As an architect, including hemplime into the building code is of paramount importance,” Ana Konopitskaya of CoExistBuild, who co-wrote the application to the ICC, told HempBuildMag. “It will allow architects like myself, focused on sustainability, to specify this product in any municipality across the US.”
And although the official rules won't go into effect for a few more years, several adventurous builders have already gotten a head start on hemp homes. Last year, a Canadian hemp company bought 1,000 acres of land in Colorado to develop eco-friendly affordable housing primarily made out of hempcrete. The US Environmental Protection Agency (EPA) has also issued grants to companies that are working to create sustainable building materials from naturally-grown hemp.
Matt Marino, builder at North Dakota-based Homeland Hempcrete, told HempBuildMag that although many US companies were already moving ahead with hemp construction projects, the IRC approval “helped add legitimacy to our craft... It is a tool for us to standardize our deliverable. This is just the beginning, and I look forward to seeing where we can take this industry.”
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