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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. If a person levels their land and piles dirt up around the trunk of a red gum tree about 2 metres higher than where the original planting above the ground was can this kill the red gum tree? My neighbour has just done this on his block of land and I was just wondering if this would kill the tree. It is a beautiful tree and there were two of them but they pushed the other one over and have covered the trunk of the last one quite high up the trunk. So just a query to make sure that what they have done won't kill the tree.

Generally speaking it's not a good idea to pile up earth round the base of a tree. You will find a lot of discussion of this topic on the net if you write "build up around tree trunk" in your browser. Having said that, different species react in different ways, with some being more sensitive than others. River red gums (Eucalyptus camaldulensis) are adapted to flooding and when water rises around the trunk they develop "adventitious" roots that grow up from the tap root, sometimes to the point where they float on the water. It's doubtful this would happen when buried under 2 metres of soil, but perhaps you should seek advice from someone more qualified in horticulture, eg. your local Botanic Gardens.

Q. I am looking to improve the speaker sound quality in our kitchen. The main surfaces in the room are Jarrah benchtops. The room is 4mx4m with 3m high ceiling. There is a large (1200x1500) island in the centre of the room and the stereo speakers are wall mounted. A number of options are being considered to 'mellow' the sound. Lower the speakers. Timber slatted ceiling panel lowered from the main 3000mm ceiling. Slotted Plywood. I can't find much info on this subject and am wondering if you might shed some light on it please.

Acoustic design is a bit beyond our expertise but it sounds as if you need some sound absorbent material in the kitchen space. As you are probably aware, hard inflexible surfaces reflect sound and distort it. Also, different combinations of materials will absorb or reflect certain frequencies more than others, again distorting the sound. Assuming this is a straightforward case where sound absorption is needed, slatted timber or slotted plywood on their own probably won't make a great difference. They will need to be used in conjunction with some sound-absorbent material behind them, eg. mineral wool batts. Sound then passes through the timber and is absorbed by the material behind. Perhaps your local supplier of sound systems could help, or failing that an acoustic engineer could give you a more informed answer.

Q. I am trying to find a solution to remove wasp/insect resin from inside door frames. Is there a solvent that will dissolve the resin? As well as a solution to deter insects from creating the same problem. I would be most grateful if you can offer any suggestions.

Shellac is an insect resin, and shellac flakes for wood finishing are dissolved in methylated spirits, so we suggest you try methylated spirits or white spirit to remove the resin from your door frames. We don't have any special expertise in repelling wasps or other flying insects, but you will find a wealth of information on the net if you write "deter insects" in your browser.

Q. White ant inspections in WA if pest activity is found 2-2.5 metres from the building BUT there is no activity in the house. Would the whole house have to be sprayed because the activity is this close to the building even though no activity is in the house?

It depends whether you have a termite barrier system in place which you are confident about, or whether perhaps you have an older style house that is difficult to fully protect. If your house is recently built, on a concrete slab with 75mm slab edge exposure and all plumbing penetrations and construction joints protected, that is a recognised barrier system. You would then simply need to be observant to make sure termites are not entering around the perimeter of the house, over the edge of the slab. If your house has a suspended timber floor supported on stumps it would be wise to inspect the sub-floor space regularly to make sure termites are not building mud shelter tubes up the sides of the stumps. In this case a baiting system might be a good precaution since termites have been found so close to your property. You can find out more by writing "termite baiting" in your browser. Perhaps you have already had a termite inspection carried out, since you seem confident there is no activity in the house. Nevertheless, regular inspections are necessary on an ongoing basis, either by you or a pest control operator, to make sure termites don't find their way in.

Q. I am looking to produce skateboards here in Australia. I would like to use locally grown and milled Timber. I need a product with the same or similar characteristics to American sugar maple. I need a minimum sheet size of 700x300x1.4mm. Can you assist or put me onto someone who can?

Veneers used for skateboards are thicker than the usual veneer production and that might make an Australian species difficult to source. Briggs in Sydney stock 1.4mm veneers in American rock maple, specially for skateboard manufacture, but as far as we are aware Australian veneer species are not produced in this thickness. However, we suggest you inquire from veneer merchants in your State.

Q. We are restoring a bush hut on the eastern side of the range near tenterfield / drake area. Near rocky river/ timbarra creek It was built in the early to mid 1900's..the external cladding is sheets of bark...possibly iron bark or stringy bark. This needs replacing so looking for information about harvesting time, techniques and best species. Timber on the propery is Iron bark, stringy bark, red gum turpentine and pine. Any info would be fantastic.

There isn't a great deal of information about bark cladding in Australia, but the species of bark that Aborigines used to make canoes would be a good guide since canoes needed thick fibrous bark. Some eucalypts have quite thin bark, but she-oak (Casuarina glauca) and stringybark were often chosen for canoe making because of their thick bark. Regarding the best time for harvesting, the bark will peel off more easily if the log is cut during the growing season (spring/summer). During winter when the tree is dormant, the layer between the bark and the wood stiffens and the bark remains more firmly attached. So try to arrange for your tree to be felled in late spring. You might find more information from your local branch of the National Trust, or the Museum in your capital city.

Q. I am building in an area which is flood affected. I am using a timber frame on concrete slab with fibre cement cladding to the inside and outside. Do you have information on this being acceptable within a flood area.... ie the timber frame with the cladding.

Assuming there are no Council by-laws to the contrary, we don't see a major problem with your proposal. It's not clear from your message how often you anticipate flooding, but for best results we would recommend preservative treated timber (CCA or ACQ, not Blue Pine) and corrosion-resistant fasteners. Plain wire nails will rust quite quickly in a damp environment. It might be wise to avoid insulation batts in the wall cavity as they will hold water if flooding occurs. With these precautions the structure should be able to survive occasional flooding, although obviously the contents will be affected.

Q. I am an Architect in Melbourne and we have a client who is allergic to formaldehyde. I understand that this chemical occurs naturally in timber, but would like to seek advice as to whether any species are worse than others or if recycled timber has less output than young timber?

Your client is under a misapprehension about formaldehyde - it doesn't occur naturally in timber and is only present in glued products, where it is a component of commonly-used glues. So it is found in products such as plywood, particleboard, MDF, glulam and so on. Having said that, glued products manufactured in Australia are produced to strict standards that limit formaldehyde emissions to safe levels. However, if your client wishes to avoid it altogether, natural timber of all species is formaldehyde-free.

Q. Looking for timber panels that help keep sound out. I have read about acoustic qualities of timber on your web site but sounds like timber being used to keep sound in but I am interested in timber panels that keep sound out.

Timber is often selected for its acoustic qualities in concert halls and churches, but this is related to reverberation and its effect on the quality of sound within the space. Timber has no particular advantage as a sound barrier, where performance is related largely to the mass of the material. Nevertheless, timber fences can be designed as effective barriers against traffic noise, and can be seen along major freeways in our capital cities. If you are building an acoustic fence or wall, CSIRO recommends that the barrier should weigh at least 15 kg/m² and be free of gaps or cracks.

Q. I would like to find a Glulam supplier in NSW. I have tried your website supplier search, but am not having much success.

A number of timber merchants should be able to supply glulam in NSW - if they don't manufacture it themselves they can buy it in from elsewhere. If you would prefer to deal directly with a manufacturer, Dale Glass Industries (DGI) at Silverwater have many years of experience in manufacturing glulam from different species of timber.


Did you know?

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