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Like to know what wood to use building a pergola or framing a barn? How about the difference between tung oil and polyurethane as a floor finish? How to revive decking or deal with merbau stains? Or how to meet the building code or bushfire standards? Or ask about the environmental advantages of wood or forest certification?

Q. I am trying to import wood (mainly for pallet making) to Korea. Can you, please, suggest several companies to deal with?

We assume you are looking for pine, in which case writing "Australian pine exporters" in your browser will bring up several company names, eg. Jamax Forest Solutions, HVP Plantations, etc. We weren't sure if you wanted to import logs or sawn timber, but one of these companies should be able to assist.

Q. I’m renovating my home (a 130 year old queenslander). I am relocating the bathroom to a room with a fireplace and a timber floor. I don’t want to remove the timber floor. Is there any way for me to waterproof it retrospectively? I’ve seen pictures of baths on old timber floors and it looks beautiful. Can I possibly get away with not tiling?

Timber floors in bathrooms do appear in the design mags, particularly from Europe, and they look great. However, if you need to apply for building approval there's no way an exposed timber floor would comply with Australian building regulations. The Building Code of Australia (BCA) refers to AS 3740 which requires a "waterproof" floor. A waterproof membrane over the timber would comply, but would defeat the purpose of the timber look. The BCA assumes a worst-case scenario where the bath could overflow, children couild be splashing around, and if there is a shower over the bath the requirements are even more strict. In your case perhaps only responsible adults will use the bath, and perhaps there is no shower above. But then the issue arises that you might sell the house to someone with an entirely different lifestyle. So I think we will have to say it can't be done.

Q. I am trying to find out about how a change in moisture content for seasoned timber will affect the strength and durability of structural timber. The scenario is that I am looking at a house that was constructed with inadequate sub floor ventilation and subsoil drainage and as such there is a large amount of condensation within the subfloor space. The floor joists and ply have been measured to have moisture content of up to approximately 41%. The house was constructed approximately 10 years ago so it is possible that the timber has been at an increased moisture content for a prolonged period of time or cycled through moisture changes during the change of seasons. So I am trying to find out whether it is possible to fix the ventilation etc and dry the timber back out, and what effect this prolonged period of time with an increased moisture content would have on the integrity of the timber's durability, strength etc. Do you know of/or where I could possibly find out some information on this topic?

There are really two parts to your question, firstly the effect of prolonged moisture exposure on strength, and secondly its effect on durability. Structural timber with a moisture content of approx. 41% is classed as "unseasoned" but it sounds as if no adverse effects have been noticed. For example, one possible effect would be increased deflection in the joists, particularly if the moisture content was fluctuating with changes in the seasons. This would show up as sagging, or perhaps increased "bounce" in the floor. Regarding durability, the timber is certainly at a level where wood rot can occur since common decay-causing fungi only need a moisture content of 20% or more to become active. If access to the sub-floor space is available the soundness of the timber can be checked by probing it with a screwdriver or similar instrument. This will reveal any softening of the wood. We assume there are no signs of mould growth or fungal strands growing on the wood. If there is no deterioration we would assume the timber is a durable species. Taking all this into account, we consider that drying out the timber is a suitable strategy, with a fan if necessary. If there is no sign of increased deflection, or decay, the timber should continue to give satisfactory service. But it is essential to provide proper ventilation and drainage in the longer term. For further information you may find it helpful to refer to our Technical Guide no. 12, available via this link: http://www.woodsolutions.com.au/Articles/Resources/Design-Construction-Guides. Although dealing primarily with flood-damaged buildings the guide includes some relevant data.

Q. I am sending you a small attachment video of our caravan, that shows you some of the damage. The timber has dry rot, and is tinder dry as you can see when I grind it to dust, to me this problem is not something that has happened in the last few years, for timber to be wet, dry out, rot and decompose to dust and also allowing time for it to travel down around the window frame which would be through gravity and capillary action. I would like you to show the video to your engineer and construction people and ask them How long this process would take from wet wood to dry sawdust? The timber in question appear to be approx. 40mm x 40mm. I am starting to believe that it may possibly be due to green timber or wet timber in the construction phase, this may be answered during the repair. I would like to thank you in advance for your help and hope you can help me, as I would not like this to happen to any one else with a van that is less than five years old.

We have viewed your video and it certainly looks like a case of attack by one of the fungi in the "brown rot" group, so-called because they destroy the cellulose in the wood and cause the remainder to darken and crumble. Typically the wood then fractures into large or small cuboidal pieces which can be crushed into dust as you have shown. It seems odd that the wood was wet at some earlier stage but apparently is now quite dry. All fungi need moisture to become active, even "dry rot". We wondered if the caravan had spent some time in an open-air sale yard before you bought it, but is now kept under cover, so that perhaps water penetrated round the window frame soon after it was built but then stopped. That seems to us a more likely scenario than building it with wet wood, although building it with wet wood could lead to the same problem. However, there would then have been shrinkage as the wet wood dried out. It seems more likely that it was built with dry wood that became wet after construction. As far as time to decay is concerned, it can happen quite quickly under the right circumstances. Aside from whether the wood was wet or dry when the caravan was built, it seems to be a fairly clear case of faulty construction if the window frame has decayed after only five years.

Q. I'm trying to find out the acoustic rating my double studded walls between townhouses. Essentially, I have a 20mm cavity separating 2 x 90x45 MGP10's, with 15mm INSULATION board and 13mm PLASTER to each side. I'm just wondering whether there's anything you have in your material that would readily tell me what the RW and Ctr would be for this.

We couldn't find data for a construction that exactly matches yours, but there is a close approximation on the Boral site which you can view via this link: http://www.boral.com.au/brochures/ordering/PDF/10592_Multiframe_Draft_9_RGB.pdf?site=boral&company=Plasterboard. If you refer to their TT2626F you will see the system involves double studs with a 20mm gap, two layers of 13mm plasterboard each side and no cavity insulation. If you need a more precise answer, Boral's TecASSIST service might be able to help on 1800 811 222.

Q. I would like the contact details for someone I can speak to regarding some questions I have on timber durability.

Telephone advice is not available through this service, but if you would like to leave a more detailed question we can give you a written reply. If you need to speak to someone, a telephone advisory service is available from the Timber Merchants Association in Melbourne, phone (03) 9875 5000. Note that previous postings directing people to the Australian Forest Products Association (AFPA) no longer apply. Their Help Line is now closed.

Q. 140(+5)fixed x140(+5) & up x2.2 mts long and above. I would like to know what the above specification means especially the beginning.

It's unclear but seems to be calling for timber 140 x 140 mm with an oversize tolerance of 5 mm, so it could be 145 x 145 mm and still be within specification. Not sure what "and above" means at the end. To avoid a dispute we suggest you contact the specifier and ask for clarification. The purpose of a written specification is to make everything clear, but this has the potential to cause confusion.

Q. We have a piece of public art that incorporates a 5 metre long timber pole that is cantilevered into a piece of sandstone. The pole became detached and we are trying to find a company that will reattach the pole securely (and provide certification as it is in a public place), without impinging on the artist's intent. Could you advise of anyone who could assist? We are based in Logan, Queensland.

We don't know for sure but it sounds like a job that a flagpole company could do. Flagpoles are sometimes mounted horizontally so it's possible someone like that could help. For example, have a look at this (and similar) websites: http://www.adwareflags.com/index.php/flagpoles.

Q. I am doing some showroom partitions and we were planning to use mdf & then gyprock. We want to mount wall cabinets. Is there a way we can use just the timber and cut cost?

No doubt the answer depends on what is going in the cabinets, how heavy they will be, and whether they are sitting on the floor or whether they are overhead cupboards. If they are sitting on the floor it should be possible to secure them by fixing into the MDF - in fact they would probably sit there by themselves as free-standing cabinets, depending on how they are designed. If they are overhead cupboards they will need to be fixed back into the partition framing. If that can be achieved, MDF should be OK without Gyprock over the top. However, that depends on whether the partition framing is timber or steel. You will get a much more secure fixing into timber, because steel framing is not usually designed for extra loads. There are really too many unknown factors to give a definite answer to your question.

Q. We were involved in the 1988 construction of a carport in Melbourne having specified 150*150 treated pine posts sitting below ground on concrete pads with 600 deep cement stabilized sand above the footing. The posts have rotted below EGL and we can't tell if the timber is treated pine or oregon. What is the best way to determine the timber type?

It's sometimes difficult to distinguish timbers by appearance, but a positive identification can be made by examining a sample microscopically. Each species has a distinctive cell structure and specialists in this field use such characteristics to identify different species. A noted expert is Dr. Jugo Ilic whose consultancy is called Know Your Wood. For details of fees and required sample size send an email to knowyourwood1@gmail.com.

WoodSolutions

Did you know?

Logs from plantations cannot produce the sawn hardwood timber produced from logs currently harvested from native forests.