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Are blackbutt posts suitable for a rammed earth footing? Previously I have used ironbark for the horse shelter frames, but supply is a problem. Blackbutt has been suggested as an alternative. 6 lengths cut three sides 3.6 m long. 

Woodsolutions Answer +

Blackbutt is rated Durability Class 2 in the ground according to Australian Standard 5604. This indicates a probable life expectancy of 15 to 25 years. If you are in a dry part of the country and the ground adjacent to the posts is not likely to be damp for long periods, and you can organize some termite protection, this estimate might be significantly exceeded. However, ironbark is rated Durability Class 1 so is a more durable species. There are not many Class 1 timbers that are readily available – other Class 1 options include tallowwood and some of the ‘box’ species (grey box, red box, white box, yellow box). You will find more details about timber properties on our website here: https://www.woodsolutions.com.au/wood-species


I have a client who has Australian cedar slabs and wants me to mill them down and use for fly screens. My question is does this timber preform the same as western red cedar? Is it a durable choice for external use with a finish?

Woodsolutions Answer +

Australian cedar is rated Durability Class 2 in ground contact (one class higher than western red cedar) so is durable enough for external above-ground use. However, it may not have the same dimensional stability as western red cedar so you will need to make sure the slabs are fully seasoned. Testing with a moisture meter will tell you. Alternatively if the slabs are freshly cut, the timber should be dried before using it otherwise you are likely to get unacceptable shrinkage.


I am searching for the 'fire rating' of American white oak. And am keen to learn if it meets Australian Standards

Woodsolutions Answer +

FWPA has sponsored fire testing on a range of timbers including American white oak. Note the typographical error – it’s actually Quercus alba, not Quercus abla. This and other fire test reports can be found on our website here: https://www.woodsolutions.com.au/articles/fire-test-reports

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