Earthen & Bio-based Construction, Fire, and Climate Change - A Call for Regulatory Action

This week, TLRS, along with the RRC and more than 1,100 others, signed a petition advocating for the inclusion of earthen materials in fire rebuild efforts. Review the petition below and add your signature to help persuade lawmakers to recognize the future of construction, which we recommend they consider!

Sign the petition.

The Issue

Dear Governor Newsom and members of the California State Senate and Assembly,

The devastating wildfires that are currently affecting hundreds of thousands of Californians have provided an emphatic reminder that California has done far too little to allow and promote fire resistant and low-embodied carbon construction. We are writing to advocate for the adoption and improvement of building regulations for earthen construction in California. This initiative aligns with the state's expressed goals for fire resistance and mitigating climate change.

Earthen and bio-based construction, encompassing techniques like adobe, compressed earth block, rammed earth, cob, hemp-lime and light-straw clay, offers a sustainable and resilient building solution. These materials exhibit remarkable fire resistance due to their high thermal mass and low combustibility. This inherent fire resistance has been demonstrated through various tests and real-world scenarios, where earthen buildings have withstood fire exposure significantly better than conventional wood-framed structures.

Furthermore, each of these earthen construction technologies represents a low-embodied carbon material. This means that their production and use release significantly less greenhouse gases compared to conventional building materials like concrete and steel. Likewise, at the end of a building’s usefulness, these materials can be easily recycled without complex processes or hazardous byproducts. By promoting earthen construction, California can reduce its carbon footprint and actively combat climate change, a key contributor to the increasing frequency and intensity of wildfires.

Despite the proven fire-resistant qualities and environmental benefits of earthen construction, California has yet to adopt any of the relevant International Residential Code (IRC) Appendices for monolithic adobe, light-straw clay, and hemp-lime construction. This lack of regulatory framework hinders the wider adoption of earthen construction in the state, depriving Californians of a safe, sustainable, and fire-resistant building option that also addresses climate change. In locations like Germany and highly seismic New Zealand where earthen building codes recognize current research and engineering, these earthen materials have become part of the ordinary construction economy.

The devastating wildfires that have increasingly plagued California highlight the urgent need for fire-resistant and climate-conscious building solutions. Earthen construction, with its proven ability to withstand fire and reduce carbon emissions, can play a crucial role in mitigating wildfire risks and enhancing community resilience while combating climate change.

I urge you to take action by directing the California Department of Housing and Community Development (HCD) and Building Safety Commission (BSC) to expedite the adoption and improvement of building regulations for earthen construction. This includes:

• Adopting relevant IRC Appendices: Integrate the existing IRC Appendices for cob construction (monolithic adobe), light-straw clay, and hemp-lime (hempcrete) construction into the California Building Code/Title 24. Notably, HCD/BSC declined to consider proposals to do just this in 2024, first saying that the proponents needed to wait for an agency-led workshop, then being told no such workshop would be held, and then finally instructed at the adoption hearings that the proposals would not be heard because no workshop had been held, with the suggestion that they should try again in three years.

• Improving building regulations: Develop comprehensive and performance-based building regulations that address the unique characteristics of earthen construction, ensuring both safety and innovation. The Masonry Society, the nation’s recognized non-profit leader in the development of masonry standards is currently working to establish improved standards for low-carbon and highly fire-resistant earthen masonry. The State of California should be encouraging and helping fund that work.

• Promoting research and education: Materials research in the United States is largely driven by profit-seeking private industry. While this is effective for the development of proprietary technologies, it frequently leaves behind low-cost and readily available existing materials and systems. Support for research initiatives and educational programs that advance the understanding and application of earthen construction techniques in California is desperately needed. The University of California-Davis’s Civil Engineering Department has established itself as a leader in earthen masonry research, but desperately needs funding to support research that will inform the seismic design criteria of these materials.

By taking these steps, California can unlock the full potential of earthen construction, fostering a more sustainable, resilient, and fire-resistant built environment while actively addressing climate change. I appreciate your attention to this critical issue and look forward to your positive response.

Sincerely,

Dan Krause & Lisa Morey, Presidents, Adobe in Action

Massey Burke, Director, California Straw Building Association

David Eisenberg, Executive Director, Development Center for Appropriate Technology

John Jordan, President, The Earthbuilders’ Guild

Stephen Colley, Architect and President, The Earthen Construction Initiative

Ben Loescher AIA, Architect & Founder, Loescher Meachem Architects / Adobeisnotsoftware

Mark Jensen, Board Member, Natural Building Alliance

Kurt Gardella, Director, Santa Fe Community College Adobe Construction Program

Dr. Michele Barbato, Professor, Department of Environmental and Civil Engineering, The University of California, Davis

Ashley Stallworth, President of the Board, US Hemp Building Association, Amanda Martin-Behrendtsen, Vice President of the US Hemp Building Association, Founder & CEO Renewal Revolution, Ventura County

Lisa Sundberg, Trinidad Rancheria member in Humboldt County, President of the Indigenous Habitat Institute