It's most likely a case of fungal decay, particularly if there is also mould present. Mould isn't harmful to wood in itself but is a precursor of decay, showing that conditions are right for fungal growth. If the timber is relatively sound where there is better ventilation, that also suggests that it's a moisture problem. If you can improve ventilation under the flooring that is closer to the ground it should lower the moisture content to the point where fungal decay becomes inactive and the softening process stops. Testing the timber with a moisture meter would provide helpful information if you have access to one. Otherwise, it seems highly likely that moisture is the problem. While adequate ventilation on its own should stop decay getting worse, you might want to apply an anti-fungal treatment if you can work safely in the confined space. We suggest a boron product. These preservatives have low toxicity to humans but are effective anti-fungal treatments.Fungal decay
There is an existing restaurant that is an adaptation of old fish cool rooms and stores with Vic Ash (best guess) flooring. The underside of the flooring is exposed to environment, directly above the sand and areas subject to tidal changes.
Some of the floorboards are soft from the underside (similar to damp?) and there is some minor mould. For those with much more elevation above the sand/water there is less evidence of the soft fibre to the boards. This suggests that where there is less clearance, it may be less ventilation. I can't be sure.
Is there a treatment to the timber that can prevent this continuing and getting worse?
I have a boundary wall of an attached garage on a house that requires a 60 60 60 fire rating. Is there any way to achieve this AND to look of real timber weatherboard ?
The Boral OutRWALL system achieves FRL's of 60/60/60 and 90/90/90, depending on detailing. The system relies on fire-resistant plasterboard as the fire barrier, so the cladding becomes a decorative overlay and can be any material, including timber weatherboards. Further details can be obtained from the Boral manual available for download here: https://www.usgboral.com/content/dam/USGBoral/Australia/Website/Documents/English/tech-guide/04685_T_OutRwall_Oct09.pdf.FRL 60/60/60
AS3660, where discussing preservative treated timber, advises of need to treat holes, cuts etc. Some manufacturers advise, within some constraints, they will warrant not treating holes, cuts etc., whereas others do not. As an industry representative body can you not work towards bring this all into line with the preference being, within accepted constraints, holes cut etc., not being required to re-treat and AS3660 to align with that. Without that, under the NCC requirements, it makes it very hard to state all building elements of a structure containing treated timber are not subject to termite attack and therefore require a termite management system, unless all holes, cuts etc are treated. The human factor of performing, without exception, the re-treatment, leaves that option very troublesome and a builder ultimately liable unless they also use a termite management system, all adding to cost to consumer.
The need to re-treat cut ends, notches etc. depends on the hazard the timber will be exposed to, as well as the warranties offered by producers. Preservative-treated timber in weather-exposed locations should have cut ends, housings and notches re-sealed to maintain the preservative 'envelope'. Preservatives don't always penetrate the complete cross-section and if cut ends are not re-sealed, untreated material may be exposed. Treated house framing, eg. 'Blue Pine', is a little different. Re-sealing of Blue Pine is generally only required if there is a major breach of the protective envelope, eg. by planing, rip sawing down the length of the piece, or cutting deep notches, since the treatment only penetrates a few millimetres from the surface. Re-sealing is not required for cut ends or holes, and warranties will not be voided in such cases. Producers' warranties can be found on the net. Note that Blue Pine house framing is not protected against wood rot, since it is not anticipated that there will be moisture in the wall cavity. It is only protected against termite attack. Note also that while the Blue Pine treatment protects the framing it doesn't necessarily prevent termites from entering the building and attacking the contents such as books, papers and joinery timber. Consequently we recommend barrier systems to keep termites out of buildings. Treatments such as Blue Pine are then a second line of defence in the event that barriers are breached.Termite protection
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