Commercial and residential architects will be able to more easily design for US buildings using hemp-lime (hempcrete) thanks to new technical resources released this week through the US Hemp Building Association.
“US architects who want to design homes and the big multi-story hemp-lime projects that are popping up in Europe have been frustrated because there’s no easy way to spec these materials in US projects,” said Ray Kaderli, USHBA president.
The USHBA Architect's Toolkit rolls out as hemp building materials are being featured in DC on the National Mall in HUD’s Innovative Housing Showcase, and the American Institute of Architecture’s A24 Conference takes place in DC.
The online technical tools support the use of low-carbon bio-based materials that can reduce the use of fossil fuels in the US construction industry.
Hemp-lime or "hempcrete" is a non load-bearing wall filler composed of the woody hurd of the industrial hemp stalk mixed with lime.
Even though hemp-lime technology has been used in Europe for 30 years, it is a new material in the US, gaining acceptance after the 2018 Farm Bill legalized the growing of industrial hemp. Hempcrete insulation moderates indoor humidity and temperature and provides excellent protection from mold and pests. Hempcrete builders in the EU and Australia report a reduction in electricity bills by 40 percent and more. Hemp-lime is also flame resistant.
Because hemp-lime is not sold by a single manufacturer, the trade association removed barriers for all manufacturers by supporting an accessible guide spec for all users.
Created in partnership with ARCAT, specs for hemp-lime wall infill material include technical data, ASTM standards (as developed), performance features and product attributes. They will be updated as more US standards are developed. The specs follow the CSI 3-part and the Canadian CSC formats for building and construction professionals.
The specs are free to view and download.
The resources will also help other design professionals, engineers and code officials.
• For commercial architects, the US Hemp Building Association partnered with ARCAT to publish specifier details for hemp-lime (Hempcrete) Thermal Insulation. Architects use guide specs when incorporating a material into a project’s construction bid documents.
• For residential architects, USHBA removed barriers for residential home projects when Hemp-Lime (Hempcrete) Appendix BL was published in the 2024 US Model Residential Codes.
• USHBA is offering AIA-CES continuing education classes for architects to learn about hempcrete.
“We’re continuing to build a toolkit to make it easier for designers to work with hempcrete,” said Board Member Tai Olson, of Chicago-based US Heritage Group.
Commercial and industrial architects are the ultimate decision-makers who can drive the supply-chain demand on an industrial scale for hemp and other natural building materials.
Some large-scale architects are already specifying hemp-lime for insulation on big projects, most notably, the Urban Sequoia, a carbon sequestering hempcrete insulated high-rise rolled out in 2021 at COP 26 and again in 2022 at COP 27 by SOM (Skidmore Owings & Merrill).
“We understand that architects want to design better, more sustainable, and healthier buildings, AND the market is demanding it,” Kaderli said. “Our trade association needs to help design professionals meet these demands,” he added. “We want to make it easier for architects to include hemp-lime in their materials selection.”