How a sleeper wall works
Soil behind a wall pushes outwards, and wet soil pushes harder. A sleeper wall resists that by stacking sleepers against upright posts that are set deep in concrete, with the sleepers fixed to the posts. The posts do the real work. Sleepers simply laid on top of each other without posts may look fine for a season, then lean forward as the ground behind them gets wet.
How high can a sleeper wall be?
Sleeper walls are best suited to low retaining work. As the height and load increase, the design needs to account for the soil, drainage and nearby structures, and a structural engineer may be needed. Where a slope is steep, it is usually better to build two or three lower terraces than one tall wall. Each step then becomes a usable space.
Drainage behind the wall
Water is the main reason retaining walls fail. Behind a sleeper wall we lay a membrane against the timber and backfill with free draining stone, so water can drain down and away rather than building up pressure. Without that, the soil turns heavy every winter, and the timber stays wet and rots sooner.
Garden levelling
- Accurate level planning
- Ground moved and compacted
- Ready for turf, patios or redesign
Terracing a sloping garden
Terracing is a cut and fill job: soil is dug from the higher part of each level and moved to the lower part, with a retaining wall holding the edge. Done well, it creates flat areas for a patio, a lawn and a play space, linked by steps. Our sloping garden guide covers the wider options, from gentle regrading to full terraces.
- Light regrading suits a gentle slope with no walls needed
- Cut and fill with low walls suits most sloping family gardens
- Two or three short terraces are usually better than one tall wall
- Steps and paths need planning in from the start, not added later
Sleepers or another material?
Treated softwood sleepers are the most affordable. Hardwood lasts longer. Some people prefer block or stone walls for a more permanent look, especially for taller retaining. Whichever you choose, the posts, footings and drainage behind it are what decide how long it lasts.