Building a Cob Cottage in Western WA *city*

My goal is to construct a cob cottage/cabin on the property next to my house, as a place for my aging parents to live. A simple space maybe 400sq ft, including (perhaps) a lofted bedroom.

The primary obstacle is I live in the suburbs (Tacoma, WA). The yard is plenty big enough, and DADUs are allowed up to 1000sq ft. Does anyone know of natural builders who could help me design this structure to code? Is it going to depend on the city's whim and, I presume, (in)experience with cob? Or is it just a matter of finding an engineer who will sign off on it? My understanding is that cob is approved in IRC under "Appendix U" and that has been approved by my city.

I'm willing to make some compromises on the natural building (ie, "conventional" slab foundation, wood framing) but I would really like the structure to be mainly cob - for many many reasons, but one is that I would like to be able to offer workshops/parties to local folks who want to learn cob.

Any insights or guidance is appreciated! Or others sharing similar experience.

Hi Casey,

Do you want to do cob or use adobe or CEB blocks?
Tacoma is on Tacoma Fault so you will have to meet seismic requirements, so either you will need to do a timber frame with cob infill or use CEB and do vertical reinforcing with rebars topped with a bond beam.
Do you need to meet some energy code (sufficient insulation in the walls)? If yes then you will have to either do light clay or regular cob and light clay on the outside.