Although our fire reports do not include an assessment of timber flooring on a rubber acoustic underlay, our technical department points out that the test for critical radiant flux (CRF) is a surface spread test, so substrates should not be an issue unless there is burn through. Therefore the figures quoted in Table 6 of our Regulatory Information Report 41117.11 would hold good in your case.

Our Technical Design Guide number 9 provides detailed guidance on the installation of timber floors. A copy can be downloaded free of charge from our website via this link https://www.woodsolutions.com.au/publications. Whether you need an expansion gap at all depends on a number of factors, including initial moisture content of the flooring, local climate, etc. Note the advice in our Guide to the effect that floors are generally more prone to shrinkage in cities with drier internal environments (e.g.

The Baigents were a prominent timber industry family in New Zealand for over a century, operating as H.E. Baigent & Sons until they were bought out by Carter Holt Harvey in the late 1980's. The stamp "BAIGENT 'S' MSG AS1748 90 x 35" identifies the sawmiller (Baigents), the 'S' indicates that the timber was seasoned, MSG confirms it was machine stress graded, and AS 1748 is the Australian Standard to which it was graded, but oddly enough the actual stress grade is not specified.

Tallowwood is rated Class 1 Durability in-ground (the highest durability rating) according to Australian Standard 5604:2022, Timber - Natural durability ratings, meaning the heartwood is resistant to termite attack and fungal decay. While the lifespan of timber in the ground varies according to site conditions (damp site v. dry site, tropical climate v. dry climate, etc) it would seem that if the poles have survived for 47 years without any problems there is no immediate cause for concern.