Terms and notes

APVMA - Australian Pesticides and Veterinary Medicines Authority

CCA: - Copper, chrome and arsenic

ACQ – Alkaline copper quaternary

CuAz – Copper azole

LOSP. - Light Organic Solvent Preservative

AS/NZS 1604 is a series of five standards specifying the preservative treatment of timber and timber products. Part 1 applies in Australia only and parts 2 to 5 apply in Australia and New Zealand.

Timber in Australia is treated to six levels called Hazard (H) Classes. These treatment levels indicate where the treated product may be used.

Hazard ClassWhere the treated wood may be usedWhat the timber is protected against
H1 Inside, under cover, protected from the weather and well ventilated Insects
H1.2** Inside, under cover, protected from the weather subject to moisture Insects and decay
H2 Inside, under cover, protected from wetting, no leaching Insects and termites
H2F Inside, under cover, protected from wetting, no leaching, envelope treated, South of the Tropic Insects and termites
H2S Inside, under cover, protected from wetting, no leaching, South of the Tropic Insects and termites
H3 Outside above ground, periodic wetting but where the timber can dry out; some leaching Insects, termites and moderate decay
H3A## Outside above ground, periodic wetting but where the timber can dry out; some leaching, maintained paint system Insects, termites and moderate decay
H3.1** Outside above ground, periodic wetting but where the timber can dry out; some leaching, maintained paint system Insects, termites and moderate decay
H3.2** Outside above ground, periodic wetting but where the timber can dry out; some leaching Insects, termites and moderate decay
H4 In or on the ground subject to severe wetting and leaching Insects, termites and severe decay
H5 In or on the ground subject to severe wetting and leaching, with or in fresh water Insects, termites and very severe decay
H6 In contact with sea water Marine borers and decay

** Applies in New Zealand only
## Applies to one preservative system used in Australia



Q1 Can I burn Tan E or ACQ off cuts?

A. The treated timber industry advises the same precautions for burning all treated timber products, i.e. that they should not be burned and they should be disposed of in landfill. The exceptions to this are for industrial processes and registered commercial incinerators.

Q2 Does the arsenic and or chromium leach out of CCA treated wood into soil?

A. The chemistry of CCA wood preservatives results in the copper and chromium and arsenic being chemically attached (or fixed) inside the wood so that it remains in the timber. Nevertheless, highly sensitive chemical analysis may detect small amounts of these chemicals in soil next to CCA-treated wood or wiped from its surface. In most cases however, these small levels are well below the concentrations found naturally present in the environment.

Q3 If horses chew treated wood, won’t they get ill, or get cancer?

A.  A horse would need to eat a lot of treated wood to have symptoms of toxicity or poisoning. Occasional nibbling won’t hurt a horse but for chronic chewers, it would be best to install a deterrent such as an electric fence (wire) along the top rail. Treated wood is often used to contain horses e.g. stalls and yards and whilst there have been some reports of sickness, it is not clear if this is from the preservative contained in the wood or from eating a lot of wood material. Use of treated wood to contain horses is not a common problem.

The current form of CCA preservatives used in Australia were introduced in the mid 1970s and is less ’attractive’ to horses than the earlier formulations.

Q4  If children touch CCA-treated wood they will get a dose of arsenic and chromium, won’t they? (Otherwise why did APVMA ban it for decks, playgrounds and some other uses?)

A.  Small amounts of chemical components may be wiped from CCA-treated wood products, however these small amounts are very unlikely to cause health problems for children. If you are concerned, normal hygiene such as washing hands after contact should be used. To limit contact with CCA-treated timber around the home, you may consider painting it with a good quality paint system.
The APVMA restricted the application of CCA-treated wood in uses such as playground equipment and decks as a precautionary measure. CCA continues to be safely used in many domestic uses such as landscaping and structural framing of decks, fences etc. All CCA-treated wood must be identified as ‘treated with CCA’.

Q5 Don’t some treaters take shortcuts and treat the wood ‘green’ resulting in a product that’s not fit-for-purpose?

A.  The best precaution against using wood that is not fit-for-purpose is to get it tested before installation. Testing however is expensive and only suitable for large jobs. Your best tactic is to look for a brand (Q8). By applying a brand to treated wood, the producer is claiming that it meets the national standard. You should keep or photograph brand tags as proof of where the timber was treated.

Q6  How can I tell if the wood has been properly treated to Australian Standards?

A.   Firstly, you should only purchase treated timber products that are labelled, as mentioned in Q9. The only way to tell if wood meets the specifications in the Australian or any other standard is by chemical indicators for the presence of treatment chemicals and chemical analysis. These tests should be performed by trained operators and registered laboratories. You should also look for the brand.

Q7  Does the richness/ consistency of colour of some outdoor treated products represent the efficacy of the treatment?

A.   No. The richness, intensity or consistency of colour is affected by many factors not related to treatment, e.g. position in a treatment stack, sunlight, temperature.

Q8  Isn’t LOSP only an envelope treatment – how can this be suitable for outdoors?

A.   LOSP stands for Light Organic Solvent Preservative and describes the type of liquid used to dissolve the part of the preservative that does the work. H3 LOSP treated wood can be used outdoors but not in ground contact.

Timber treated to AS/NZS1604 specifications has been proven to perform outdoors. Proof is required before a preservative system is approved for listing in the Australian Standard.

Q9  What does the treatment brand on timber look like and what does it mean? What does each element describe?

A.   A treatment brand will usually look like the example below although other layouts are allowed in AS/NZS1604.

999 02 H3

The ‘999’ identifies the treatment plant that applied the actual treating process. A list of treatment plant numbers is maintained by the Timber Preservers’ Association of Australia
The ‘02’ identifies the actual preservative that has been used. This number is mainly used by testing agencies to indicate what chemical to analyse for.
The ‘H3’ tells you where the treated wood may be used or the biological hazard the wood will be exposed to. Please refer to the Terms and Notes.


Q10  Is treated timber weather proof?

A.   Strictly speaking no timber is weather-proof and the colour will grey and the timber may “check” or crack over time as it gives off and absorbs moisture. All timber absorbs and gives off water depending on local conditions. In Australia, preservative treated wood means wood that is protected against insects, and/or termites and/or decay or rot and/or marine borers. You need to apply a surface coat to protect wood against weathering.

Q11  Are the chemicals and process used to treat timbers safe?

A.   All timber preservatives are registered by the APVMA, which considers the effectiveness of the preservative and its safety in the anticipated uses. A registration is only granted when the preservative satisfies these two criteria.

Q12  Can treated timber be used in contact with vegetable gardens?

A.   Studies have shown that preservatives such as CCA and creosote are not absorbed into food crops like grapes, tomatoes and cucumbers. Some root crops like carrots and beetroots have been reported to pick up small amounts of arsenic from CCA, but it is in an organic non-toxic form and in any case is largely removed by peeling the vegetable.

Q13  Can all treated timber be used outdoors?

A.   No - Some timber is treated for use indoors only e.g. H1 & H2 exposure. These applications are where the hazard is from insects and termites and the timber does not get wet. Coloured H2 and H2F house framing and engineered timber products which are treated for termite and insect attack are NOT suitable for weather exposure of any kind.

Q14  How long does the treatment stay effective in the timber?

A.   It is impossible to give a definite answer to this question. Research has shown that all of today’s preservatives give long effective lives in use and it all depends on where and how the treated timber product is used. Timber treated to H3 for example will last a lot longer in Mt Isa compared to Innisfail in tropical North Queensland. Whilst such things are under review all the time, timber treated to AS/NZS1604 specifications will satisfy the performance (expected life) requirements listed in the Building Code of Australia.

Q15  How do you safely handle CCA-treated timber?

A.   You use exactly the same precautions for handling CCA-treated timber as you would for handling untreated timber. Sensible, normal practices and hygiene should apply, e.g. minimize exposure to sawdust particles and splinters by using suitable masks and gloves and washing hands before eating.

Q16  Can I dispose of CCA at the local tip / landfill?

A.   Small amounts of treated timber waste, such as off-cuts generated during home projects may be disposed of through normal household waste collection services or at local landfills. Treated timber should not be placed in any green waste or garden organics recycling bins.
Trade users of treated timber should be able to dispose of treated off-cuts through normal commercial waste collection services or at local landfills. However, regulations and local services vary so you should contact the local council, the state environment protection agency, or your treated timber supplier for advice on disposal or recycling options.

Q17  Do I need to reseal end-cuts on treated timber and what is the best product for this?

A.   With the exception of envelope treatment of framing, preservative treatment completely penetrates the sapwood and there is only limited penetration around exposed heartwood. If the piece is sapwood only, there is no need to coat cut ends with preservative. However, it is unlikely that a piece of treated wood is all sapwood so it would be prudent to coat fresh cut ends before installation.
To carry out end-coat treatments, you can buy wood preservative in cans from a hardware store or larger paint suppliers.

Q18  Do I need to oil or coat treated timber?

A.   Preservative treatment only protects the wood against attack by insects, termites and decay or rot, see Q9. To keep the wood looking good, it should be coated with a paint, or stain or water repellent. Uncoated wood will still resist attack by insects or rot, but it will weather to a grey surface with time.

Q19  Can I install H4 treated veranda posts directly into the ground?

A.   H4 treated posts can be installed straight into the ground, but this is not best practice. For example, use a water barrier like a malthoid or polyethylene wrap around the post before back-filing, and especially if you are setting the post in concrete/cement. Also if the deck is over a meter off the ground, the TPAA recommendation is to use either H5 treated material with a water barrier wrap or install the post on stirrups out of ground contact. If the post is cut, ensure it is resealed before installing in the ground where the use of concrete is recommended.

Q20  Why is some treated timber I buy not green? Is it still suitable for outside use?

A.   The colour of treated timber depends on the preservative used for treatment or whether a dye/pigment/stain has been added to the treatment solution. Usually the green colour is imparted by the copper in a preservative, e.g. CCA, ACQ, CuAz. Colour is not a good indicator of treatment quality.
The Hazard part of the treatment brand (Q8) is the only indicator of where the treated product can be used. You should not buy unbranded treated timber as the producer may not be prepared to stand behind his product and you cannot rely on the level of treatment.
Treated wood with a H3 brand may be used outside above ground, and H4 or H5 branded timber can be used in ground contact (see the Hazard Class table above)

Q21  What nails, screws and fixings should be used with treated pine?

A.   TPAA recommends at least the use of hot-dipped galvanised coatings for nails, screws and fixings for all outdoor applications. In more extreme conditions or near the coast, stainless steel fixings and connectors should be used. Some manufacturers produce connectors with special coatings and the manufacturers recommendations should be followed for their use. It is also important to design the connections to drain and shed water and to reseal any cut ends

Q22  Can I use a nail gun to fix decking, cladding and palings using galvanised coil gun nails?

A.   Decking nails should be ‘deformed or ring-shanked’ (have visible twist or ribs) with a rounded head. This type of nail is not currently available for use in a nail gun. The deformed shank nail is used to reduce ‘pull out’ and the rounded head is recommended to reduce any part of the nail sticking proud of the wood. These are specific decking nails.
Galvanised coil gun nails are OK for use on palings. These should have a flat head to hold the paling more firmly to the fence rail. For length and diameter of nails, consult manufacturer or timber association advice.

Q23  My deck has gone grey and cracked, how do I fix this?

A.   Greying and cracking of timber will occur when wood is exposed to the weather. There are some formulations claiming to repair the wood but their effectiveness is minimal and treatment needs to be repeated. The best thing to do is to fill and sand any cracks and paint the wood with a light coloured paint.

Q24  Can I fix hardwood decking over treated pine bearers and joists?

A.   Yes - Consult nail manufacturers advice; generally treated pine bearers have good holding power but require longer nails than hardwoods for fixing.

Q25  Is the H2F “blue”- treated pine poisonous?

A.   Blue treated framing is envelope treated, and the wood is protected against attack by borers and termites. This treatment may only be used south of the Tropic of Capricorn. The actual treatment chemical is colourless and the blue colour has been added to indicate that a treatment has been applied. The APVMA-registered preservatives are poisonous to termites but safe to use. You should use normal hygiene practices before eating etc.

Q26  Is there any documentation on possible side effects of using or contacting H2F “Blue” framing treatment – for example, itching on the skin?

A.   We cannot find any documentation on this issue, but it is possible that skin irritation and throat issues may be caused by the solvent system used in some H2F treatments. Blue treatment is applied in controlled facilities where contact with the treatment solution is minimised. For frame and truss plants, builders, etc., normal treated wood handling precautions apply when using Blue framing timber, i.e. use gloves and eye protection and dust masks when cutting the timber. These precautions will minimise contact with the chemicals in the outside envelope around the wood. A very few users experience side effects such as itchiness. If this is the case you may be sensitive to the chemicals and should minimise contact and ensure that hands are washed after handling the wood and a barrier cream used where possible. If symptoms persist, consult your health professional.

Q27  My outdoor timber really smells (like turpentine or petrol). Is this bad for me?

A.   The petrol-like smell is the liquid/solvent that the preservative is dissolved in. These are LOSP preservatives. Wood that has recently been treated with LOSP should be used in a well ventilated place. The hazard is similar to the hazards from petrol and white spirits (mineral turpentine). While LOSP-treated timber is stored and used without any issues, some users may be sensitive to the smell and with contact with the timber. If so, similar precautions to using Blue pine (see Q26) should apply

Q28  Who do I talk to if my treated timber has decayed/rotted out?

A.   If you feel that the treated timber used in your project has failed prematurely, you should talk to the person or company that sold you the wood in the first place. If you do not know where the wood came from, the only thing you can do is replace the affected timber.

Q29  Is there any chemical / process that I can use to treat my timber frame / trusses for termite protection once on site or installed?

A.   Termite treatments such as H2F blue framing treatments are applied in controlled factory environments which cannot be done on site.

Q30  When handling “Blue” framing timber I get blue colour on my hands. Will this make me sick?

A.   See also Q25 and Q26. It is best to minimise contact with any treated timber product. However, if you do get blue colour on your hands this should be washed off before eating or contacting other parts of the body such as eyes, etc. In general, very little treatment chemicals will come off on your hands. The blue colour is a dye or pigment used to show that the timber has been treated. The blue dye/pigment is not dangerous.

Q31  I am using Blue framing timber and there are “clear spots” on the timber. Will termites attack it? (This is where the blues dye hasn’t fully covered the timber)

A.   If there are extensive areas where the blue colour is not present on the timber, you should discuss with your supplier. However, if there are a few spots of non-blue on the framing timber it is extremely unlikely that the termites will attack the timber.

Q32  Is timber treated to a higher level if the blue dye is a darker colour than other producers?

A.    No. The blue dye is an indicator only and has nothing to do with how well the timber has been treated.

Q33  Can I use Blue (H2F) product out in the weather?

A.   No. H2F treated material is not for use in weather exposed applications. Note also that Blue framing can be used south of the Tropic of Capricorn only. Red, H2 pressure treated timber may be used for framing north of the Tropic of Capricorn.

Q34  Can I use H3 treated LVL outside in full exposure to the weather?

A.   Any timber product that has been branded with H3 according to the specifications in the standard may be used in weather exposed, above ground applications. However, consult with the manufacturers specifications or call them for advice. While the veneers may be treated for insect attack and rot, they may grey and check unless a suitable coating system is applied and maintained.

Q35  How important is a brush on wood preservative on cut ends of envelope treated plywood, LVL, glue laminated timber and reconstituted wood based products ?

A.   It is very important to apply a brush on wood preservative to cut ends of envelope treated plywood, LVL, glue laminated timber and reconstituted wood based products. Two flood coats, wet on wet are recommended. Envelope treated plywood, LVL, glue laminated timber and reconstituted wood based products have the letter 'E' following the brand (TN1 under the publications tab on this web site). Envelope treated product must also carry a warning label that cut ends must be treated with a brush on preservative. Remember if it is not branded, it does not comply with the Australian/New Zealand Standard on wood preservation (AS/NZS 1604).





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