Treated Sleepers

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At Centenary Landscaping Supplies there is a wide range of Pine Treated Logs and Treated Sleepers that can be used for retaining walls, garden edging, pergolas or arbors, and indeed any timber landscape structure.  Our Treated Sleeper range is available in both pine and hardwood timber.Large stockholdings of most of these products including our Treated Logs and Treated Sleepers are available 7 days a week for you to either pick up in your own vehicle or to have delivered at an agreed time to your home. 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 treatment method. Copper Chrome and Arsenic (CCA) protects the treated 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 any child play equipment, 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.

Levels of Treatment

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.

Timber for Retaining Walls

The timber we sell that can be used in retaining walls, can be divided into the following groups:

CCA Treated Hardwood Sleepers

Taken from a variety of hardwood species including Ironbark, Grey Gum, Spotted Gum and Yellow Stringer. You have to remember that when buying hardwood, it will always be of poorer quality than that used in the building industry, and is termed “Landscape Grade”. For example, a timber sleeper only has to have one good face and one good edge to be considered okay. This is an important consideration when deciding on the construction method you will be choosing for your retaining wall and it is a good idea to come and see the actual timber sleepers before buying them.

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.

CCA & ACQ Treated Pine Sleepers

Most of the pine timber we sell is harvested from the State Forests near the Glasshouse Mountains, although some is 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, with pine being much lighter with a green tinge.

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.

Unlike the hardwood, pine timber comes with a 40-year guarantee against termite and fungal attack, and this is because the timber is not as dense as hardwood, so that when it is treated under pressure the chemicals can penetrate all the way through the timber thus giving it complete protection. This guarantee does not however 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.

Pine sleepers are treated to the H4 level. If you are looking to build a vegetable garden, a sandpit …. And 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.

DIY How to Build a Timber Retaining Wall with Treated Logs or Sleepers

Site Preparation

Video 2
Sleeper Wall Construction

Video 3
Drainage Behind Retaining Wall

Video 4
Log Wall Construction