The design of timber rounds is covered in AS 1720.1-2010, Timber structures, Part 1: Design methods. Table 6.1 in Section 6 gives the relationship between the Strength Group of a species and its Stress Grade. For example, radiata pine falls into Strength Group S6 (unseasoned) and the related stress grade is F11. If not from a 'mature' tree the designer would apply a reduction factor. It is assumed that the round material complies with AS 3818.11, which deals primarily with allowable splits and straightness.

The life span of H3 treated pine compared to various hardwoods can be estimated by reference to our Technical Design Guide no. 5 titled Timber Service Life Design.

We can now advise that Regulatory Information Report 41117.11 has been extended to 30 April 2025 by Warringtonfire Australia - refer Letter of Extension LOE 1.2 available on our website here: https://www.woodsolutions.com.au/resources/standards-codes/fire-test-reports.

It is correct that our Regulatory Information Report 41117 version 11 refers specifically to NCC 2019. This will be updated at the next review. Meanwhile our technical people advise that It is not really the year of the NCC that matters, but the test method that is referenced.  NCC 2019 Amdt1 and NCC 2022, as will NCC 2025, require group numbers to be determined in accordance with AS 5637.1. and critical radiance flux to be determined in accordance with AS ISO 9239.1.