A Summary of the 2002 Revisions to the California State Guidelines for Straw Bale Structures
by Martin Hammer-Architect, Berkeley, California
A two year process to revise the California State Guidelines for Straw Bale Structures came to a fruitful end on
April 26, 2002 when California Senate Bill 332 (SB332) was signed by Governor Gray Davis. Upon his signature the
Bill immediately became law within the State. The State Guidelines, also known as HS18944, were originally adopted
in 1995 as AB1314. The Guidelines are voluntary only, and must be formally adopted at the local level (City or
County) before they are utilized or enforced, although they are sometimes referred to even when they haven't been
officially adopted. In practice, in the State of California, these Guidelines are the closest thing to a Straw
Bale "Building Code" that exists.
Much has been learned about straw bale construction since 1995, and SB332 revised the previous California Guidelines
because they contained "requirements that . . . were either unnecessary or detrimental." The following
is a summary of the changes:
In order of appearance in the Bill.
· The guidelines also apply to grains other than rice. [18944.30(c), 18944.35(g)]
· Two story load bearing structures are allowed, with design by an architect or engineer. [18944.33(f),
18944.40(c)]
· More explicitly allows lime, lime-cement, or earthen plasters. [18944.33(h)]
· 360 lb/ft shear value is accepted for straw bale walls plastered both sides with cement or lime-cement
plasters. [18944.40(e)]
· Foundations are no longer required to be the width of the bale wall. [18944.40(f)]
· Interior pinning requirement is eliminated, with design by an architect or engineer. [18944.40(i)(2)]
· Allows no moisture or vapor barrier membrane on bale walls, with design by an architect or engineer. [18944.40(l)(1)]
The legislative process went very smoothly until two weeks before the end of the 2001 session, when the Building
Standards Commission (BSC), and Housing and Community Development (HCD) recommended a veto by Governor Davis. They
were concerned that straw bale building standards were bypassing the normal building code review process that BSC
administers. A last minute meeting in September, 2001, between those agencies and 3 CASBA (California Straw Building
Association) members salvaged the Bill, producing two results. SB332 was modified so that large, unwanted parts
of the previous Guidelines were reinstated (e.g., internal pinning!) but "windows" were given to allow
alternate methods, if designed by an architect or engineer. Also, both agencies committed their support for straw
bale construction to eventually be included in the State Building Code. Bruce King and the Ecological Building
Network (EBNet in Sausalito, CA, www.ecobuildnetwork.org ) are currently
conducting extensive straw-bale testing that should help facilitate that.
The text of SB332 can be viewed on this website or on the State of California's website at: www.sen.ca.gov.
Click on Legislation and follow from there. The final version is "Chaptered 4/26/2002". Although our
ideal version of SB332 became somewhat compromised, the key changes we sought were incorporated.
(Questions regarding the State Guidelines for Straw Bale Structures can be forwarded to Martin Hammer at 510-525-0525,
or
mfhammer@pacbell.net )