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Is WA Blackbutt (Euc. Pilularis) compliant with any BAL levels, if so which ones as decking and wall cladding?

Woodsolutions Answer +

Blackbutt is one of the seven timbers rated 'bushfire-resisting' and therefore is compliant for all uses (decking, wall cladding, bushfire shutters, fascias, verandah posts, etc) up to and including BAL-29. At the next level (BAL-40) externally exposed elements are generally required to be non-combustible, so timber won't comply. However, timber cladding can be used in the higher BAL levels if installed over a barrier of fire-resistant plasterboard, eg. the Boral OutRwall system, more info here: https://www.usgboral.com/en_au/solutions/plasterboard-systems/outrwall-fire-rated-external-wall-system.html.


Have recently installed a 14mm timber floor board system glued to a 12mm ply substrate that was mechanically fixed to a concrete slab. There is a plastic vapour barrier under the ply. Since install, the floor boards (glued and secret nailed) have cupped and gaps have formed at each plank joint. What needs to be done to rectify.

Woodsolutions Answer +

This is a problem that might need a building inspector to get to the bottom of it. The Australasian Timber Flooring Association (ATFA) has experienced inspectors located around the country. There are two possible causes of cupping in flooring. There may be moisture from underneath making the underside swell, or there may be drying from above making the top surface shrink. Moisture from underneath is unlikely since there is a vapour barrier. An inspector will be able to assess whether the interior of the building is unusually dry, whether the flooring was at a suitable moisture content at the time of installation, and other relevant factors. The inspector should also be able to advise on rectification, which will depend on the severity of the shrinkage and cupping. You can request an inspection here: https://www.atfa.com.au/request-an-inspection. 

Flooring, cupping

Can 14mm thick floorboards be used as external cladding and simply top nailed into wall studs? Shiplap profile is far more expensive than flooring.

Woodsolutions Answer +

Floorboards can be used for external cladding but because the tongue and groove joint is a tight fit, any movement in the timber is very visually obvious. Shiplap and other cladding profiles are designed so shrinkage is less noticeable. You would need to make sure the flooring is a durable species that will stand up to the weather, assuming it is fully exposed. Also flooring (and cladding) is usually 19mm thick for best results.

Floorboards, cladding
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