There will be no lingering rot issues once the timber has completely dried, even though it's untreated. The fungi that cause rot need moisture to progress and can't survive in dry wood. If there are insulation batts between the studs they should be removed to facilitate drying and it would be helpful to take some readings with a moisture meter, rather than relying on touch. Naturally, the surface of the timber will dry first, and may feel dry, but there could still be moisture in the core. Moisture meters can be hired if your office doesn't possess one.

Our Regulatory Information Report RIR 41117.10 shows that all commonly used timbers fall into Group 3, including the Tasmanian oak/Vic ash species (alpine ash, mountain ash and messmate). A copy of RIR 41117.10 can be downloaded from our website via this link https://www.woodsolutions.com.au/resources/standards-codes/fire-test-reports.