We’ve been working with various earthen walls with heavy timber or a timber & hempcrete (or cob) infill for the mass and fire resistance. The mass is critical. All borrowed from Northern European practice with a bit of QA/QC. Thing about fire is the radiant energy through the windows. The RE alone can ignite interior fabrics and some surfaces if the structure is enveloped. So you need fire shutters or something similar as well.
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