What Parts of Tennessee CAN I build Cob?

Good day. Glad to be here. Is cob a fair building material for high humidity West TN? I've heard otherwise but considering where cob structures originated I know it seems to work fine. I've been watching My Cob House on YouTube and I've seen other things in videos. I'm highly allergic to molds. That's a big factor in my interest in cob.

Can you reply if you live in an area in TN where you have legally built a cob dwelling?

Cob can be used almost anywhere, its just a matter of protection of the wall by design of the roof.
There is a topic here which deals with cob and high humidity.
Cob breathes and with designed airflow, not accidental airflow it works well to prevent mould.

Cob is a traditional building technique in Devon, UK. It has been used in many other parts of the UK and in Ireland too. Most of those places would be considered humid and, in the winter, it's not uncommon for it to rain for several weeks without a break.

As John mentions, protecting the walls with the roof (large, overhanging eaves) is the key. Cob loses all structural integrity when it is soaked.

Other strategies here include a thick layer of lime plaster on the outside of the cob, providing some weather resistance.

"Rough casting", a textured external plaster, is another technique that is used to increase the surface area of the render and allow moisture to evaporate faster. I've seen this used more on stone cottages in Wales than on cob, however.

This post might help explain:

John said, "Building codes usually prescribe how a building is built, not what you build it with. The building department will want to see plans that show you framing the walls up right with the proper fire stops and sheathing. The inspector will come out and make sure it is installed correctly with the proper lathing and weep screeds. Now what you choose to slop onto the lathing, be it stucco or adobe or cob or tabby, that's pretty much up to you. The inspector is not going to come out on cobbing day and look over your shoulder to make sure you have added the right number of bags of lime to the mix.

https://permies.com/t/28585/cob-legal-Tennessee#223667