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I am currently writing our waste management procedure, and would like to know if there is any treated timber that does not come under the classification of "Timber that has been treated with preservatives" under "Schedule 2 Materials that must not be burnt so as to discharge visible smoke into the environment" in the Environmental Protection (Unauthorised Discharges) Regulations 2004. We are looking at what off-cuts of timber can be burned as energy recovery as part of our waste minimisation programme. Many thanks

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The answer to your question turns on what the regulations mean by ‘preservatives’ and what they aim to achieve. There doesn’t appear to be a definition of a ‘preservative’ in the regulations, so a strict interpretation might prohibit the burning of any treated timber. On the other hand the aim of the regulations seems to be to prevent visible smoke in the environment, which suggests that if treated timber can be burned without discharging visible smoke into the environment, then that would be acceptable. It’s not recommended to burn timber treated with arsenic-based preservatives unless it’s done under controlled conditions, because arsenic is given off in the smoke and left behind in the ash. However, the regulations don’t seem concerned with this potential problem. But timber treated with creosote would clearly be prohibited since it gives off a black oily smoke. Then again ‘Blue Pine’ (house framing treated against insect attack) is only treated with a low-level chemical such as permethrin, as used in Mortein, which would not leave a dangerous residue nor produce any more smoke than untreated timber. We feel you really need to get a ruling from the WA Environmental Protection Authority, taking into account the kind of treated timber you propose to burn.

treated timber, burning, waste disposal, waste management, smoke, emissions

I'm writing to you on behalf of one of our schools in Victoria that is part of the sustainable schools program. They are having some maintenance work done and some of their old weatherboards need replacing. The students noticed that the boards were not Australian and upon research discovered that they are coming from Russia. Aware of the Global Miles and the lack of suitable accreditation they have stopped the repairs until they can source a local product. The builder is a green builder and even he doesn't know where they can source local product. Can you assist me in advising if there is a local product and who the suppliers would be?

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Our organisation does not discriminate against imported timber – in doing so we could be in conflict with Australia's commitment to free trade between nations. However, we certainly support proper accreditation and certification of wood products. If that is lacking in the case you describe, there are locally-produced products that could be used. Radial Timber Sales produces weatherboards from silvertop ash, using a technique specially developed to maximise recovery from small logs. The environmental benefits of this process are described on their website. Boral Timber also produces weatherboards from locally-grown hardwood. Finally, don't overlook Weathertex, an Australian-made reconstituted cladding material made from sawmill waste and forest thinnings.

For more information about the design, construction and maintenance of timber decking, download the free WoodSolutions guide – Domestic Timber Deck Design.

Weatherboards, silvertop, Russia, Weathertex

Can treated timber be used to build vegie gardens? Is there any leakage of preservative into timber? This is for a school project so there will be a lot of parent scrutiny.

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There are two main types of preservative currently in use for consumer products, CCA and ACQ. CCA is the one that causes concern since it contains arsenic. A number of studies have shown that CCA is not absorbed into above-ground food crops such as grapes, tomatoes and cucumber. There are some reports of a slight increase in arsenic content in root crops such as carrots and beets grown against treated timber, although the arsenic is in a safe organic form and most of it is removed with peeling. Any possible concern can be eliminated by growing these vegetables more than 100 mm from treated-timber garden edgings, or by lining the edgings with plastic. This has the additional useful effect of reducing soil contact with the wood, which could further extend the wood's life. Alternatively, ACQ-treated wood can be used with confidence since it does not contain arsenic. Our answer is based on information provided by the research organisations CSIRO and Scion.

Treated, treatment, preservative, CCA, ACQ

Regarding the calculation of carbon sequestration rates for various tree plantation species - how can I access this information, or what are the accessibility criteria?

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There is no need for trees planted for carbon sequestration to be of any particular kind. However, a useful calculator (the Carbon Sequestration Predictor) has been developed by the New South Wales government and its use is explained in their Prime Facts newsletter of January 2010. A copy of the newsletter can be downloaded from the net at, and the calculator itself can be downloaded from

Carbon sequestration, plantation, calculation

I am after some timber advice for a project in Perth - the site is approx. 1km from the beach. I would like to know what species are available and appropriate for the following: 1. Structural roof framing timber exposed to weather - sections from 150 - 250 deep. 2. Structural columns penetrating ground - approx. 100x100. 3. Structural columns not penetrating ground - approx. 100x100. 4. Other roof framing members semi-exposed - approx. 90x45. 5. Rough sawn ceiling battens exposed - approx. 45x45. I would also like any information on the sustainability rating of the selected timbers.

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Timber is relatively unaffected by salt, although some permeable softwoods when left uncoated can suffer salt attack if crystals form in the wood structure. That shouldn't be a problem 1km from the beach, but to be on the safe side perhaps a hardwood would be preferable. On the other hand, if the timber is painted that will prevent salt attack and other timbers such as treated pine could be considered. In the hardwood group, members out of ground contact but exposed to weather (roof framing, ceiling battens and some columns) could be karri which is a Durability Class 2 timber above ground. Columns in the ground will need to be a more durable species, e.g. jarrah or perhaps one of the durable eastern States hardwoods (spotted gum, ironbark, tallowwood, etc.). WA species under the management of the Forest Products Commission are certified under the Australian Forestry Standard. As well as selecting suitable timbers, careful choice of fasteners is needed to avoid corrosion in a salt environment.

Coastal, beachfront, framing, column, battens

How environmentally friendly are LOSP, CCA and ACQ?

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LOSP uses solvent (usually white spirit, similar to dry cleaning fluid) as a carrier for the preservative, but little solvent remains in the wood after treatment. CCA and ACQ are both water-based preservatives. The main issue with CCA is its arsenic content. Studies have shown that only minor traces of preservative leach out in service, but disposal at end of life (and disposal of offcuts) is not well organised and is generally via landfill. ACQ has been developed as an arsenic-free alternative to CCA and is now used for all domestic decking. We consider that there is no significant hazard to the user with any of the three, but ACQ is probably considered the most environmentally friendly on the basis that it is water-based and arsenic-free.


Would you please be able to advise what the best environmentally friendly wood is that I could use to build a pergola? I would ideally like to use hardwood, but it is heavy and difficult to work with, so maybe you can suggest the best sustainably treated pine?

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If you prefer treated pine for your pergola it is all produced sustainably from plantations in Australia and New Zealand. Various treatments are used - for situations above ground, pre-primed pine is available, treated with a light organic solvent preservative (LOSP). For timber in the ground, or in contact with the ground, CCA and ACQ preservatives are used. These give the wood a greenish tinge because of the copper in the preservative solution. However, pine that is treated with CCA or ACQ can be painted like any other.

Pergola, treated pine

What is the best way for people to go about sourcing sustainable timber for their decks? What are some good plantation species to look out for? What is the best timber to choose in terms of durability? What are the best hardwood options, and what price do they start at per linear metre?

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We consider that any Australian-grown species that is available commercially can be considered sustainable. Our native forests are managed to world’s best practice through sustainable forest management regulations and codes of practice. Furthermore, over 90 per cent of managed public forests in Australia are subject to additional voluntary standards which are independently certified through international sustainability standards such as the Program for the Endorsement of Forest Certification (PEFC). When it comes to imported timbers, species from developed countries such as the US, Scandinavia and Europe are produced under much the same conditions as Australian timbers. Developing countries, for example in the S-E Asian region, are at different stages of sustainable forest management. This is where certification can help, for example under the Forest Stewardship Council (FSC) system. Plantation pines are not sufficiently durable to be used outdoors without preservative treatment, but they can be readily treated to a level of durability equal to or exceeding that of the most naturally durable species. To compare the natural durability of different species, we refer to Australian Standard 5604, "Timber - Natural durability ratings" which gives a rating on a scale of 1 to 4 for commonly used species, both in-ground and above-ground. As an independent advisory body we don't quote prices, but a phone call to a few timber merchants should provide a guide.

Sustainable timber, environmentally friendly, plantation timber

I am a landscape contractor. I currently have a client who has asked for a deck to be constructed using a sustainable timber. I am just after any information you could give me on what timber types to recommend to them. Thanks in advance.

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Presumably treated pine would be acceptable since it is sourced from plantations established for the express purpose of providing timber. In our view the production of Australian hardwoods is also sustainable, and you could choose any of the commercial species in the knowledge that strict environmental guidelines are applied to their harvesting and regeneration. Technically, most of our native timbers today come from regrowth forests. For example, the Victorian ash forests were severely burned in the 1939 bushfires, but regenerated and were then harvested for timber once they matured. After the recent bushfires the cycle will begin again. Three-quarters of the jarrah forests of W.A. had been cut over by the early 1900's (Woods & Forests Dept., Western Australia, Report 1916-17, Govt. Printer, Perth), so most of our jarrah now comes from regrowth forest. The various State forestry departments or equivalents all produce detailed reports of their activities which are available in the public domain, most of them downloadable from the net. I think you will see that a high standard of environmental management is applied. The Federal Government is required to publish a report every five years called Australia's State of the Forests Report, as part of its commitment to the Montreal Process. This provides an overview of our forest management and can be downloaded here. Good management is backed up in many cases by forest certification, i.e. externally accredited environmental management systems, the most popular scheme being the one based on the Australian Forestry Standard. When it comes to imported timbers your client might want to see similar evidence of certification by a third-party organisation such as the Forest Stewardship Council (FSC) and/or chain-of-custody certification. Your timber supplier should be able to provide these details.

Environmental building

Can you use H4 treated ecowood (tan e) in garden beds?

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Tan E (Tanalith Ecowood) is a copper azole compound. It provides an alternative to the better known CCA treatment for timber in hazardous situations such as ground contact. Tan E gives equivalent protection to CCA, and H4 is the appropriate Hazard Class for timber in a garden bed. Tan E is also suitable for situations where CCA is now restricted, such as patio decking and playground equipment, since it is arsenic-free. However, there are no restrictions on the type of timber that can be used in garden beds - CCA and Tan E are both suitable.

Ecowood, CCA, H4, garden bed

On this website there's a statement that says: "There is no evidence to prove that harvesting timber from native forests has reduced overall forest biodiversity or led to the extinction of any species of plant or animal." Is this true? Where's the proof?

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The statement is based on information contained in a document prepared by the Bureau of Rural Resources (a part of the Commonwealth government) and submitted to the Resource Assessment Commission's Forest and Timber Enquiry: ‘There is no evidence that intensive harvesting has caused the loss of any plant species... [Executive Summary paragraph 7] 'Vertebrate species ... are ... with few exceptions, widely distributed ... Therefore, for conservation of vertebrate fauna it is not necessary to conserve every forest stand. Any extinctions of forest-dwelling species have been associated with non-logging factors... [Executive Summary paragraph 8] Provided appropriate environmental safeguards are implemented [eucalypt ecosystems] are able to recover from intensive harvesting and to re-develop their structural and floristic identity [Executive Summary paragraph 10]’. The full citation for this reference is: Lacey, C. J., Davey, S. M. and Harries, E. D. 1990. Intensive harvesting of native eucalypt forests in the temperate regions of Australia: Environmental considerations for sustainable development, submission to RAC Inquiry into Australia's Forest and Timber Resources, Bureau of Rural Resources, Canberra. The results of the RAC enquiry support the statement - and can be found in Resource Assessment Commission 1992. Forest and Timber Inquiry Final Report Volume 2A, Appendix H, environmental impacts of forest use.

Biodiversity, extinction, endangered species, natural habitat

I want to buy bookcases made from Australian hardwood timber. The retailers I have visited have assured me that the timber they use is 'sustainable', but have been unable to supply further detail. How can I be sure the timber really is sustainable?

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Maybe the retailers are just relying on the fact that all Australian timber is produced under strict guidelines. We are certainly confident that the production of Australian hardwoods is sustainable, and you could choose any of the commercial species in the knowledge that strict environmental guidelines are applied to their harvesting and regeneration. Technically, most of our native timbers today come from regrowth forests. For example, the Victorian ash forests were severely burned in the 1939 bushfires, but regenerated and were then harvested for timber. After the recent bushfires the cycle will begin again. Three-quarters of the jarrah forests of W.A. had been cut over by the early 1900's (Woods & Forests Dept., Western Australia, Report 1916-17, Govt. Printer, Perth), so most of our jarrah now comes from regrowth forest. The various State forestry departments or equivalents all produce detailed reports of their activities which are available in the public domain, most of them downloadable from the net. I think you will see that a high standard of environmental management is applied. The Federal Government is required to publish a report every five years called Australia's State of the Forests Report, as part of its commitment to the Montreal Process. This will give you an overall view of our forest management and can be downloaded here.

Bookcases, sustainable, Australian timber, guidelines

A new, very large solar PV farm in Spain is using wood mounting frames, not steel or aluminium, to mount the glass photovoltaic panels. Can you put me touch with local wood designers/fabricators for a 60 panel 10kW solar farm for Moama district NSW?

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Good to see wood recognised as a more environmentally friendly product than steel or aluminium. We don't have details of fabricators in the Moama district, but suggest you talk it over with a truss and frame plant. Alternatively, a joinery works in your area should be able to help. We are not familiar with the weight of photovoltaic panels but if they will impose a significant load on the mounting frames it might be necessary to have the frames designed by a consulting engineer. It will also be necessary to choose naturally durable or preservative treated timber since the frames will be exposed to the weather.

Solar farm, wood frames

How can I calculate how much carbon is stored in a piece of furniture or product, e.g. a wood bowl? Does it change with types of wood?

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The denser the wood, the more carbon is stored in a specific volume, so a stick of jarrah stores more carbon than the same size stick of balsa wood. This variation between different types of wood is taken into account by calculating carbon content according to the weight of the object. About half the dry weight of a tree, or wood product, is carbon.

It takes 3.67 tonnes of carbon dioxide (CO2) to produce one tonne of carbon, so if you know the weight of your bowl you can work out how much carbon it contains and how much carbon dioxide it has taken from the air. (For example, 2 kg of wood contains approximately 1 kg of carbon that took approximately 3.67 kg of CO2 to produce.

Carbon, storage, density

I am building a pergola, I like the timber look, the wife likes colour bond - which one is the better choice for the environment and also lasts longer?

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Timber has two major environmental advantages over steel products - one is that timber requires relatively small quantities of energy to produce, and the other is that it stores carbon. Trees grow on solar energy and we don't have to dig up the countryside to extract it. Trees also take carbon dioxide out of the air while they grow, and use it to form the various carbon compounds that make up wood. You can find out more about this on our website by clicking on the tab at the top of the page that says "Environmental Benefits". Regarding how long the two products last, that depends on how the structure is built, where it is located and how it is maintained. Timber structures built from durable timbers, or preservative treated timbers, correctly designed and well maintained will last almost indefinitely, and so will steel structures if they are correctly designed and built. One advantage timber has over steel is that it performs much better in a marine environment, so if you are building near the sea, timber is certainly the better choice!

Pergola, roofing, colourbond

Hello, I am having some furniture made and I would like to know what the best choice is environmentally, Radiata pine from NZ or Malaysian kauri pine. Thanks, Ellen.

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New Zealand radiata pine is planted and harvested like any other crop, although on a somewhat larger scale than other agricultural products. As far as we are aware there are no doubts about the environmental qualities of New Zealand radiata pine, much of which is independently certified by the Forest Stewardship Council (FSC). You can find out more about the certification of New Zealand pine on the internet. Malaysian kauri pine is more commonly known internationally as damar minyak (Agathis borneensis). This species has been recommended for listing in Appendix II of the Convention on International Trade in Endangered Species (CITES). If the recommendation is adopted, trade in damar minyak may be subject to greater regulation in future, but this does not necessarily mean it is a threatened species. While there are no restrictions on trade at present under CITES, you may wish to seek further information from your supplier about the source of the timber being offered, including details of any certification.

Pine, kauri, radiata

I'm doing a school project on energy efficiency in buildings. Can you tell me how much energy is used to make different building materials?

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The figures for different materials can differ slightly, depending how the energy use is calculated.

Approximate energy requirements for creating a cubic metre of material are:

Timber - 750 MJ.

Concrete - 4,800 MJ.

Steel - 266,000 MJ.

Aluminium - 1,100,000 MJ.

So, in terms of energy requirements, timber uses much less than other building materials.

Energy efficiency, building materials

I have some wood left over from a project, can I recycle it?

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There are various ways to recycle wood, depending on the type and quantity. Most larger cities and towns in Australia have companies that specialise in recycled building materials. If you have sought-after types and sizes of timber, you might be able to sell your leftovers. Alternatively, you could donate the timber to a charity or sheltered workshop if it is suitable for making useful items. If your leftover material just consists of scraps, you can always use it for domestic fuel!


There seems to be a lot of conflicting evidence about different building materials. Why is wood better?

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Wood has many advantages, such as it takes less energy to convert logs into timber than to produce any other common building material and we can grow more wood to replace the timber we use. Other building products are derived from limited resources. Although some products may have large resources to draw upon “now” we can only grow wood products, not steel or concrete.

Building materials, wood

Can using more wood help climate change?

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Some people think we should leave our forests untouched, to store carbon. However, trees only take carbon dioxide from the atmosphere while they are growing. The more rapidly they are growing, the faster they remove CO2 and store carbon.

Mature trees require little or no carbon dioxide while over-mature trees may actually give off carbon dioxide as they begin to decay.

When we use wood to build something, we are putting carbon into long-term storage, making way in the forest for a new, vigorously growing tree.

Climate change

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