Retaining Walls Direct

For 2000mm sleepers at 1.8m post spacing, you need approximately 1 sleeper per 200mm of wall height per 2m run. A 1.0m high wall that is 10m long requires approximately 50 sleepers (10 rows of 5 sleepers per row). Use the calculator above for your exact dimensions.

Standard post spacing for concrete sleeper retaining walls is 1.8m centres. For a 10m wall, you need 7 posts (one at each end plus one every 1.8m). For walls over 1.0m or in heavy clay soils, post spacing may need to be reduced — contact our team to confirm.

For walls up to 1.0m in standard soil conditions, 100 Series C-channel PFC posts are typically adequate. For walls over 1.0m, heavy clay soils, or any surcharge load (driveway, vehicles, structures), 150 Series or H-beam UC posts are recommended. See our guide on C-channel vs H-beam posts for full guidance.

The standard rule is one-third of the total post length in the ground. For a 1.0m wall, use a minimum 1.5m post with 500mm in the ground. In heavy clay or for taller walls, greater embedment may be required. Our calculator adds 500mm to the wall height to recommend the minimum post length.

In most Australian states, retaining walls over 1.0m require a building permit. Some councils have lower thresholds. Always check with your local council before starting construction.

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