I’m writing you in the hopes that you can help spread the word about an exciting fundraising campaign to help make cob building legally accessible to all. You have a following as a teacher or as an informational resource. We urgently need your help spreading notice of our campaign to your mailing list, newsletter or Facebook page.
I am on the board of the Cob Research Institute (CRI), a non-profit founded in 2008. One of our goals has been to write a code for cob and to submit it as an appendix to the IRC, similar to the exisitng appendices on straw bale and straw-clay construction. After years of combing the world’s scientific literature for data on cob and performing our own testing program in collaboration with three California universities, we are nearly ready to submit our code. However, we need to raise $50,000 to complete testing and code writing, and to shepherd our code through the bureaucratic review process. Time is tight, as we must submit our code by mid-January in the hopes that it will be adopted in 2021.
To gain this needed support we have created a GoFundMe / Crowdrise crowdfunding campaign. The link to our campaign is: http://www.crowdrise.com/o/en/campaign/cris-cob-code-effort. CRI is a 501(c)3 and any donations are tax-deductible.
Here’s a bit more about the code we are writing. We are still drafting the language, so some details may change, but I want to give you a flavor for what we are proposing so you can feel good about supporting it. As much as possible we intend to maintain cob’s status as a low-impact, user-friendly building technique. At the same time we need to propose requirements that are defensible based on testing, field experience, building code precedent and accepted engineering practice. Cob walls will be allowed prescriptively (non-engineered) for load-bearing and shear walls in Seismic Design Categories A and B. In these areas, which comprise about 75% of the contiguous USA, traditional-style cob with just straw for reinforcement will be permitted. We are not recommending under any circumstances the addition of chemical stabilizers such as Portland cement or asphalt emulsion. There will be some requirements about the connections to the foundation and the top plate. Builders will have to make samples of their cob mix and get these tested for compressive strength at a lab.
The recent testing CRI has performed of cob shear walls (more tests are imminent) indicate that cob’s capacity to resist lateral loads in moderate to high seismic areas does not allow a perscriptive lateral design. Therefore, cob walls will be allowed in Seismic Design Categories C, D and E (including almost all of CA and NV, central and western OR and WA, and parts of a number of other states) only with an engineered design, which likely will mean the stamp of a licensed engineer or architect. In these regions cob walls will likely require steel reinforcement such as 6”x6” welded wire mesh like that used to reinforce concrete slabs, and the required connections to foundation and top plate will also be more robust.
Note that since most states have energy performance codes, the use of cob walls for heated habitable buildings will be limited to temperate or hot climates, unless additional insulation is added to the walls. CRI has just conducted tests at an accredited laboratory to determine cob’s thermal resistance, using a widely accepted ASTM standard. The cost of this test is one reason CRI is seeking funding support.
We will happily share more details of the code once it has been fully drafted. We welcome your input! You can also find out more about our organization and mission at the web site below.
Thank you for your support!
Michael G. Smith - CRI Director