At this time the only countries with Earthen Building appendices in their codes are New Zealand, Germany, the UK and France. The International Residential Code now has Straw Bale and Light Straw Clay appendices thanks to the hard work of many progressive architects, engineers, builders attending the Committee meetings for many years. They have prepared the path for Cob as well as more natural building modalities to be added on in their own appendices as well in the near future. Engineering testing is currently being performed at the University of Santa Clara in San Jose, CA on cob wall panels as well as individual units. This is fantastic news for the future of “legal cob building” in California, the US and everywhere. Stay tuned here and at the Cob Research Institute’s website, or add yourself to their newsletter list.
If your building department requires an AMMR (Alternate Means & Methods Report) , you will need to hire an engineer or architect to craft a design plan to have your cob building approved. It is not as complicated as it sounds and a shortcut would be to design a post and beam roof support system with non-load-bearing cob walls. If you live in a county that uses Code K, you are fortunate. It is the owner-builder code which allows you more freedom to get your non-code prescribed cob building approved. Currently there are 12 counties in CA that accept Code K. Please visit the Cob Research Institute’s website www.cobcode.org for the latest information on building a permitted cob building as well as references to building professionals that can help you.
In France there is a resurgence of earthen construction, called “pisé” , “torchis” and “bauge” in certain regions which traditionally used their clay soils to build with. They are renovating as well as building new walls with their traditional technique of ramming earth inside of wooden forms that move up the wall. In England and Wales cob is well-accepted and there are regions, like Devon, where there is a higher presence of old cob houses with 2-foot wide foundations. Germany is also active and has a section for Earthen Building in their Codes. Biking through Europe there was not one country that did not have earthen buildings in their rural areas. While I legalized the first load-bearing cob building in the coastal area of California (high earthquake risk), I do not recommend retrofitting an existing cob building, at least not if you have to do the unfortunate things I had to, to mine. I sure learned alot!
My engineer, Brad Streeter, based in Santa Cruz, California, helped me to keep the cob house and have it legally recognized by the City of Santa Cruz. The process was hellish and cost almost $16K, most of which went to Brad, who was engineering his first cob house. Many lessons were learned along the way which will make it easier for those who follow me. This was a goal I have had for a while and so I was determined to follow through before selling the whole property with 2 legal cob structures on it. This would be my great accomplishment for cob education in the local building department and for local awareness of cob. If you want to see what I had to do it is clearly laid out in the Fundraiser Video my son and I made.
In addition to Brad, I worked with Anthony Dente, out of the Bay Area, who is an avid cob and structural engineer contributing greatly to the legalization of cob with his research and efforts.
John Fordice has spearheaded the beginning of a Cob Building Code with the Cob Research Institute based in Berkeley, California and is a central clearinghouse for the latest developments on legal cob building.
Bruce King is an engineer and architect who is known for his knowledge of straw bale and cob, as is Martin Hammer, a Berkeley-based architect working avidly on the upcoming Cob appendix to the IRC. He was lead author in the Straw Bale and Light Straw Clay appendices.
Michael Smith is my go-to brilliant cob builder and all-around knowledgeable expert in conventional and ecologically-friendly construction methods. Author of several books, he now lives quietly with his family in northern California on their goat and veggie farm, while continuing to teach workshops, consult and write.