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Blackwood Standard concrete sleepers are steel-reinforced (40–50 MPa) retaining-wall sleepers with a deep, rich dark finish — for contemporary, dark-palette landscaping. 200mm high in 75 to 130mm thicknesses and 1800–3000mm lengths, they stack horizontally between galvanised steel posts. Australian-made and delivered Australia-wide by Retaining Walls Direct.
Written and product-checked by the Retaining Walls Direct team — supplying concrete sleeper retaining walls across Australia. Last updated: June 2026.
The Blackwood concrete sleeper brings bold, sophisticated character to a wall — a deep dark tone that pairs beautifully with black Colorbond fencing, dark steel posts and lush green planting for a high-end result, with the strength and zero-maintenance performance of steel-reinforced concrete. Built to the principles of AS 4678 Earth-retaining structures.
Thickness: 75–80mm for standard residential walls; 100–130mm for taller walls, surcharge loads or wider post spacing. Length: longer sleepers (to 3000mm) mean fewer posts but a higher load per post. Each course is 200mm high, so a wall needs about 5 sleepers per metre of height, per bay — use the retaining wall calculator or the concrete sleeper buying guide.
| Finish | Blackwood — deep dark standard |
|---|---|
| Height | 200mm |
| Thicknesses | 75 · 100 · 120 · 130mm |
| Lengths | 1800 · 2000 · 2400 · 3000mm |
| Strength | 40 MPa standard / 50 MPa heavy duty |
| Reinforcement | Steel reinforced |
| Brand | Retaining Walls Direct (Australian-made) |
| Compliance | AS 4678-2002 Earth-retaining structures |
Unlike timber, Blackwood concrete sleepers won't rot, warp, split or attract termites, need no oiling or painting, and typically outlast timber several times over — a higher upfront price but lower cost over the life of the wall.
Pair with galvanised steel posts — C-channel for walls under 1.0m, H-beam for taller walls or clay (see the steel post sizing guide). Finish with caps, brackets & hardware and drainage — ag pipe, geo matting, or a drainage kit. See How to build a concrete sleeper retaining wall.
Water behind a wall is the number-one cause of failure — always plan drainage (drainage guide). Walls over 1.0m or near boundaries/driveways/pools generally need engineering and council approval (engineered walls over 1 metre).
Send your postcode and quantities for a freight quote, or contact the team.
What does the Blackwood finish look like?
A deep, rich dark standard finish — bold and sophisticated, ideal for dark-palette and contemporary designs.
What sizes does it come in?
200mm high, in 75/100/120/130mm thicknesses and 1800/2000/2400/3000mm lengths.
How strong is it?
40 MPa standard, 50 MPa heavy-duty available. Steel reinforced, AS 4678 compliant.
Which posts do I need?
C-channel for low walls, H-beam for taller walls or clay — see the steel post range.
Do I need council approval?
Walls under ~1m are often exempt; taller, boundary or driveway walls usually need approval and engineering.
Can you deliver to me?
We deliver across most of Australia. Send your postcode and quantities for a freight estimate.
