Image of kids playing in backyard with modern sleeper retaining wall | featured image for treated sleepers.


Treated Timber Sleepers

At Centenary Landscaping Supplies we carry a wide range of timber sleepers including both CCA and ACQ treated pine and CCA treated hardwood. They are perfect for a multitude of applications including retaining walls and garden edging. 

Our treated sleeper range is available in both pine and hardwood timber and we carry a large stockholding to quickly and easily fulfil even the largest of timber requirements. It is important to note that we have a timber guarantee that means you can buy with confidence, knowing that you will get the best quality treated logs available.


All timber sold at Centenary Landscaping Supplies is treated. Most are treated using the common CCA method. This stands for Copper, Chrome and Arsenic (CCA) and protects the sleepers from both fungal attack (rotting) and insect attack (termites). Copper is the fungicide, Chrome the insecticide, and Arsenic is the fixing agent that holds the chemicals in the wood.

Over recent years there has been growing concerns about the safety of such chemicals in timber, and Europe and America have moved away from such treatments. In Queensland, CCA treated timber is now not allowed to be used in schools or playgrounds, but can still be used in general landscaping. Slowly there is a move towards ACQ treated products. If you are planning a vegetable patch or an area where children will be in close contact often (sand pits etc.) the alternative ACQ treated timber is recommended. For general landscaping, such as retaining walls, garden edging and so on, CCA treated sleepers are acceptable and widely used.


Treated Landscaping TimberSize (mm)
CCA Treated Pine Sleepers
2.4m x 200mm x 50mm
2.4m x 200mm x 75mm
3.0m x 200mm x 50mm
3.0m x 200mm x 75mm
CCA Treated Hardwood Sleepers
2.1m x 200mm x 50mm
2.1m x 200mm x 75mm
2.4m x 200mm x 50mm
2.4m x 200mm x 75mm
ACQ Pine Sleepers
2.4m x 200mm x 50mm
2.4m x 200mm x 75mm
CCQ Pine Garden Edging
4.8m x 100mm x 16mm
4.8m x 150mm x 25mm

Buying treated timber can be tricky… even for professionals. Sometimes you can’t be certain how much you need to complete the job. That’s why at Centenary Landscaping Supplies we will help you calculate what is required and will take back or exchange any timber that is not needed, provided it is resalable.


Ready to buy? Head on over to our online store and get your next Landscaping Project underway.




Timber Treatment Levels

There are different amounts of treatment put into the wood depending on what it is being used for and it is very important that the timber you buy is treated to the level required for the job at hand. When building a retaining wall, the treated sleepers will be in contact with the ground and therefore have to have a treatment grading of “H4”. The gradings are:

  • H3 …. Exterior use but above ground (e.g. fence rails and palings, pergolas, etc.)
  • H4 …. Exterior use in ground (e.g. retaining walls and fence posts)
  • H5 …. In contact with water (e.g. jetty or pontoon)

A second type of grading that is used on timber is related to its strength and while this is especially important in the building industry, it is also important to be mindful when landscaping. The strength of a piece of timber is the F rating. Most landscape hardwood is graded F7, while most pine is graded F5.  High quality building grade timber (which we do not sell) is generally around F14. For most domestic retaining walls, the F5 Pine is more than adequate although, if building a retaining wall over one metre, council approval is required and more than likely will require an engineered drawing.



Hardwood or Pine?

All varieties of sleepers sold at Centenary Landscaping Supplies can be used for retaining purposes. Your selection will depend on a number of both aesthetic and structural factors.

Hardwood sleepers are sourced from a variety of hardwood species including Ironbark, Grey Gum, Spotted Gum and Yellow Stringer. It is important to understand that when buying landscaping hardwood, it will always be of poorer quality than that used in the building industry, and is termed “Landscape Grade”. For example, a landscape graded sleeper only requires one good face and one good edge to be considered of acceptable quality. This is an important consideration when deciding on the construction method you will choose for your retaining wall. We recommend viewing the actual stock your order will be picked from before placing your order.

While the hardwood is treated, it comes with no guarantee against termites or fungal attack, primarily because during the treatment process, the chemicals only penetrate the outside couple of millimetres (because the wood is dense and “hard”). This means that if a crack opens up in the timber, or it is cut, untreated timber becomes exposed. So the treatment of hardwood will only minimize the risk of attack, not stop it altogether. Hardwood sleepers are treated to the H4 level. Any cut or planed sections should be re-sealed with a timber sealer before installation.

Most of the pine timber we sell is harvested from the State Forests near the Glasshouse Mountains, although some are imported from New Zealand. The range of sizes in pine is different to those in hardwood so be careful. The overall appearance and quality of pine is much better. Hardwood is mainly dark brown in colour, while pine is much lighter with a green tinge (the treatment).

Some customers know that this green colour has something to do with the treatment (it is actually from the copper) and believe that unless the timber sleeper is green in colour it hasn’t been treated properly. You can be reassured then that ALL our timber is treated, and that the extra green is generally when that pack is at the base of the treatment tank and sits in the copper residue a bit longer. With all pine timber, you will find a stamp on the end of it that shows when and where it was treated, and this is our assurance that the process has been followed correctly.

As pine is a softer wood, the treatment is often more effective. However, the effectiveness of the treatment does not mean that the piece of wood will always look perfect. It will still age, weather in the sun and potentially crack and bow just like any other piece of wood. Obviously, this can be minimised by applying wood stains or other protecting paints/oils. As with hardwood, any cut or planed sections should be re-sealed with a timber sealer before installation.

Pine sleepers are treated to the H4 level. If you are looking to build a vegetable garden, a sandpit or are concerned about the CCA Treatment then we now have in stock a range of ACQ Treated timber sleepers. These have a slightly darker appearance and are a little bit more expensive than the CCA sleepers. The ACQ treatment (Alkaline Copper Quartenary) which does not contain arsenic and chromium, give many people peace of mind when constructing timber structures in the home landscape.


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