Strawbale construction

Original draft

  1. Benefit: Very high insulation; local, renewable materials with low embedded energy
  2. Code needs: Non-load bearing has code already in Arizona, California at least: both seismic and not. See
  3. Local examples: Strawbale structure at Pedro Ferbel’s in Sellwood is first permitted in Portland.

Revise point 2:

Code needs: Improve existing code to eliminate requirement for vapor-barrier; include additional, fully tested structural engineering approaches; educate inspectors, etc.

Based on comments from Jeff Richardson:

Straw bale codes do exist in the state of Oregon. In fact a Eugene Architect was involved in the whole thing. What you want is Appendix M of the Oregon 2005 Residential Specialty Code.

The international code is accepted and modified or not by the individual states. It is in the Oregon version of the code and in use. There are numerous examples of fully permitted structures both post and beam infill and load bearing all over Southern Oregon. As of yet post and beam infill seems the most prevalent in the state. Largely due to a
desire for more complicated structures by many and a need for educating the building departments.

That said... the code is somewhat out of date. It needs to address shear value of the plasters for one thing. It also needs to have the requirement for a vapor impermeable barrier to be removed - as this runs counter to the desire for breathability in a strawbale wall. There are also new strucutral studies that have gone through full independant testing that are available outlining new methods of construction. This new method has numerous examples in Southern Oregon. I helped the local structural engineer compile the information from that testing and it is in heavy use in the area now.

New tested structural technique for StrawBale can be found here. They did all the testing to prove shear values on a strawbale wall using this technique. The Ecological Building Network (Who I highly recommend you might want to work with) Hired Tipping Mar structural engineers to develope and have tested the system - look here and click on Research. You'll find both the shearwall testing with the new method outlined as well as research for a strawbale arch. Nothing wrong withthe strawbale structural method outlined in the codebook.... they just need to include the new method as well.

You can also find a lot of good technical info on everything from fly ash concrete to strawbales from the Ecological Building Network at

There aren't any real barriers to building with Straw Bale these days.... you just have to educate the building department sometimes. It is much easier if you can get a structural engineer to back you up. I knkow a good one in Southern Oregon who already has it down.


Strawbale code - vapor barrier

The section of the existing code that is pertinent from the 2005 Oregon Residential Specialty Code.

Sectioin M109.1 Moisture Protection

the paragraph at the end that reads "A vapor barrier paint having a 1-perm dry cup rating or less shall be applied to the interior wall finish of straw bale walls which separate heated and nonheated spaces and exterior walls for compliance with Section N1104.9.1." Should be removed from the code book.

There should be a clause inserted into this section of the code which reads "Vapor Barriers shall not be installed on Straw Bale walls."

For pertinent information on why this needs to happen see the article at this website

Jeff Richardson
Richardson Drafting and Design

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