Timber Treatment

Timber Treatment Information

What are the common types of timber treatment, their benefits and suggested applications?



This stands for copper chromium arsenic. It is the most effective and common treatment used in fencing and landscaping applications, and has been used in Australia since the 1970’s.

CCA treated fencing and landscaping timber is by far the most widely accessible, and is stocked by every timber retailer and hardware store. This treatment is considered by the industry as ‘standard’.


This stands for alkaline copper quaternary. This was developed as a ‘safer’ alternative to CCA in close contact applications, and has been in use in Australia since the 1990’s.

Copper Azole

This is more commonly known by brand names, such as Tanalith®E, NatureWood® CA and MicroPro®. It is also considered a ‘safer’ alternative to CCA in close contact applications.


This stands for light organic solvent preservative, and is a spirit based solvent that contains copper naphthenates and synthetic pyrethroids as well as other chemicals. It can only be used in applications where it doesn’t make contact with the ground (or in areas constantly damp or moist) as it can only be treated to H3.



  • fencing
  • retaining walls
  • garden edging


  • vegetable gardens
  • playgrounds,
  • schools & daycare landscaping

Copper Azole

  • vegetable gardens
  • playgrounds,
  • schools & daycare landscaping


  • above ground, weather protected applications such as internal beams


Is CCA-Treated timber suitable for use in vegetable gardens?

Studies have shown that preservatives such as CCA 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.

However, due to the close proximity of the timber and the vegetables, for customer peace-of-mind we do recommend alternative treatments.

Does the arsenic and or chromium leach out of CCA-Treated wood into soil?

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.

timber treatment

EcoFence treated with LOSP H3 treatments, suitable for child care projects

Enhance timber durability, Extend service life.

Improving resistance against fungi and insects,
and protecting against weather.

What treatments are suitable for decking and children’s playground equipment?

The APVMA (Australian Pesticides and Veterinary Medicines Authority) determined in 2005 that for ‘close contact’ applications such as children’s play equipment and decking that non-arsenic treatments be used.

The non-arsenic treatments are ACQ, Copper Azole and LOSP.

What timber can I use for schools and child care centres?

In schools and childcare centres (and places similar in nature), all outdoor structures would be considered ’close contact’. Therefore, only non-arsenic treatments should be used.

The non-arsenic treatments are ACQ, Copper Azole and LOSP.

Why is CCA most commonly used then?

CCA is the lowest cost, and widely considered the most effective, timber treatment available. As a result, it is the preferred treatment of most consumers and tradespeople.

How do you safely handle CCA-Treated timber?

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.
Hazard ClassWhere the treated wood may be usedWhat the timber is protected againstCommon Treatments
H1Inside, under cover, protected from the weather and well ventilatedInsectsLOSP
H2Inside, under cover, protected from wetting, no leachingInsects and termitesLOSP
H2F Inside, under cover, protected from wetting, no leaching, envelope treated, South of the TropicInsects and termitesLOSP
H2S Inside, under cover, protected from wetting, no leaching, South of the TropicInsects and termitesLOSP
H3 Outside above ground, periodic wetting but where the timber can dry out, some leachingInsects, termites and moderate decayCCA, ACQ, Copper Azole, LOSP
H4In or on the ground subject to severe wetting and leachingInsects, termites and severe decayCCA, ACQ, Copper Azole
H5In or on the ground subject to severe wetting and leaching, with or in waterInsects, termites and very severe decayCCA
H6In contact with sea waterMarine borers and decayCCA

Where to buy? We can always be contacted

Call Us 1300 598 223