Where timber makes sense
Timber sleeper walls are at their best when the job is modest. A raised bed for vegetables, a low step between a lawn and a garden bed, a soft edge along a path, a short wall holding a gentle bank in a back corner. At those heights the loads are small, the wall is easy to replace in future, and the look of the timber is part of the point.
They are less suited to tall walls, walls carrying a fence or driveway, and boundary walls where replacement would mean disturbing a neighbour. For those, limestone, concrete sleepers or engineered block are usually a better long-term choice.
Pine or hardwood
- Treated pine is the most common choice. Make sure the sleepers carry a treatment rating suitable for in-ground contact, and that cut ends are treated where the supplier recommends it.
- Hardwood sleepers are heavier and have a darker, more rustic look. Durability varies by species, and they can split and move as they dry, so check what is being supplied.
Whichever timber you choose, the posts are often steel rather than wood. Galvanised steel posts set in concrete last longer than timber posts in damp ground and are not attractive to termites.
How they are built
The builder sets out and digs post holes, stands the posts and concretes them in. Once the concrete has cured, sleepers are stacked behind the posts and fixed. Drainage still matters: fabric behind the sleepers stops Perth's fine sand from running out through the joints, and aggregate with a pipe at the base relieves water pressure after rain. Without those, even a low timber wall can bow outward after a few winters.
Living with a timber wall
A few habits extend the life of a sleeper wall:
- Keep reticulation sprays from soaking the face and the base of the wall
- Leave a gap between garden mulch and the bottom sleeper where possible
- Look along the base once or twice a year for soft timber, mud tubes or sagging
- Replace damaged sleepers early, before the soil behind them starts to move
Replacing an old timber wall
Many Perth gardens have timber walls from the 1990s and early 2000s that are now soft at the base. When a timber wall is replaced, the old sleepers and posts have to be removed and disposed of, and any sand that has slumped through needs to be dug back. It is also a good time to add the drainage the old wall probably never had, or to step up to a longer-lasting material if the wall is on a boundary.
Termites and bushfire areas
Subterranean termites are present across much of the Perth metro, and buried timber is an obvious target. Treated timber, steel posts and good visibility at the base of the wall all help.
In the hills and other bushfire-prone parts of Perth, timber close to the house may also be relevant to your bushfire planning. If your property has a bushfire attack level assessment, ask the builder whether timber is appropriate near the house or whether a non-combustible wall is the better choice. Our Perth Hills page talks about building walls on those blocks.
Comparing the options
If you are weighing timber against masonry, the cost guide shows how the price bands compare, and the limestone and concrete sleeper pages explain where those walls do better.