From wood solutions 37R , we are working on a project with fire protected timber. For penetrations, we can see 4.9.3 provides details related to penetrations and diagrams in Appendix A. Can you please provide some details if proposed method is from BCA or if these systems are tested systems by WoodSolutions?
The diagrams in Appendix A of our Technical Design Guide 37R are not tested systems, nor extracts from the BCA. They are test procedures to establish Resistance to the Incipient Spread of Fire (RISF), that is, they are to assist in setting up the tests. However, Section 5.14 of TDG 37R (page 102 onwards) provides assessed details from an Accredited Testing Laboratory that comply with the requirements of the BCA.
Tasmanian ‘oak’ is a marketing name that includes three similar timbers, alpine ash, mountain ash and messmate. All three fall into Group 3 as confirmed individually by our Regulatory Information Report 41117.11. A copy of RIR 41117.11 can be downloaded from our website via this link https://www.woodsolutions.com.au/resources/standards-codes/fire-test-reports.
We are not familiar with the problem you describe. It should be possible to sand Tas oak (even 'aggressively') without causing colour change. Tas oak normally varies in colour from straw, to pink, to reddish brown as illustrated here https://thetimberline.com.au/pages/tasmanian-oak. The timber in your image looks very dark so perhaps sanding it has generated enough heat to darken the wood. We can't suggest a remedy, other than turning the treads over, so the darkened wood is on the underside. Sorry we can't be more help.
