Thanks Bob and Michael!
I should mention, we are using a charred cedar rainscreen over the sheathing.
Though, I would love to use earth, clay, and/or lime on other projects. Not sure our clients are open to that just yet. Also the setbacks on the project have restricted us to 8" walls to create the desired interior layouts.
So when mass is not achievable, what are the low-carbon options for sheathing?