Estimate blocks or sleepers, backfill gravel, drainage pipe and concrete footing for a retaining wall.
Enter the wall length and the retained height, then choose between walling blocks or timber sleepers (landscape timbers). The tool returns the wall face area, the number of blocks or sleepers, the concrete for a strip footing, the free-draining gravel backfill and the drainage pipe you will need.
| Element | Purpose |
|---|---|
| Concrete footing | Spreads load onto firm ground |
| Free-draining gravel | Stops water pressure building behind |
| Drainage pipe (weep holes) | Lets trapped water escape |
| Batter / lean-back | Tilts the wall into the bank |
A 6 m long, 0.9 m high block wall = 5.4 m² of face. With 440 × 215 mm blocks (≈ 0.095 m² each) that is about 57 blocks, on a strip footing of roughly 6 m × 0.4 m × 0.2 m ≈ 0.5 m³ of concrete.
Tip: any wall over about 1 m / 4 ft that retains soil often needs engineering sign-off or a permit — always check local building control or building codes first.
Yes. A layer of free-draining gravel and a perforated land drain at the base relieves water pressure, which is one of the main causes of retaining wall failure.
As a guide, a strip footing roughly twice the wall thickness and 150 mm deep suits low garden walls. Taller walls need a wider, deeper engineered footing.
Rules vary by area, but walls retaining more than about 1–1.2 m, or near boundaries and buildings, often need design checks and approval. Check with your local authority.
Concrete blocks, poured concrete, brick, natural stone and treated timber sleepers are all common. Concrete and stone last longest, while timber is cheaper but has a shorter life.
A rough guide is about one-tenth of the wall height, with a minimum of around 215 mm (one block) for low garden walls. Taller or load-bearing walls should be sized by an engineer.
