There’s plenty of historical evidence that natural buildings hold up to time- witness the adobe California Missions or the 13th century cob cottages of Devon, England- but this type of anecdotal evidence doesn’t help anyone trying to conform to building codes.
There are no building codes for most types of natural building. Instead, builders work with engineers who lack the hard data to prove the viability of many types of natural materials. At times, in some areas, they are able to use an existing building code for a material like adobe for a cob structure.
The one material that does have a fair amount of testing and data is straw bale, thanks to California clean air legislation from the 1990s. When legislation banned California rice growers from burning their rice straw in the fields they sought to develop a market for their waste product.
“So the rice growers had a very, very strong economic incentive to support the development of straw bale building so they’d have a market for their straw bales which is great,” explains natural building expert Michael G. Smith, “but in the absence of that, there’s nobody trying to sell dirt, there’s no industry out there pushing the sale of clay soil or stones or natural sticks or wood chips. So the question becomes who’s going to get behind and really fund the very expensive research that needs to happen to make these things more accessible to people wanting to build to code.”
In this video, Smith shows us community center going up using cob, slip straw and straw bale that is being built to code on the property of the Emerald Earth Sanctuary. He talks about how while the natural materials can support most of the structure without things like steel, their architect was left with no recourse, but to insist on it. “There’s no codes yet for most of these techniques so to do the engineering for this building we basically just had to pretend that the earth walls weren’t there.”