Failing Retaining Walls in Greater Sydney

Why we see this constantly in Greater Sydney

Sloping blocks through Strathfield, Burwood and Concord have a lot of retaining walls, many of them 50+ years old and built without proper drainage. Sandstone block, brick or rendered concrete walls bulge, crack or lean as the hydrostatic pressure builds up behind them. Repair depends on the wall type and severity — sometimes weep holes and drainage fix it, sometimes the wall needs partial rebuild, sometimes full replacement with engineered design.

Strathfield, Burwood, Concord, Homebush and Parramatta cover the suburbs from the Inner West out toward Western Sydney. Housing here ranges from Federation and inter-war brick homes through to post-war fibro and brick veneer, plus newer apartment stock around the rail corridors. Reactive clay soils are widespread, and many of the older homes have shallow footings that move with seasonal moisture changes.

Signs to watch for on your property

• Wall visibly leaning forward at the top
• Bulging or bowing in the middle of the wall
• Cracks running vertically or diagonally through the wall
• Gap opening up between the wall and the ground or structures behind
• Water seeping through or around the wall after rain
• Soil settling or subsiding behind the wall
• Salt staining (efflorescence) on the wall face

How we fix it properly

1. 1. Inspect and diagnose

   We check the wall, the footing, the drainage and the conditions behind it. We determine whether the wall can be saved with stabilisation and drainage works, or whether rebuild is the honest answer.

2. 2. Expose the back of the wall

   We excavate behind the wall to expose the footing and the drainage zone. This is dirty work but there is no substitute. You cannot fix drainage without getting to it.

3. 3. Install proper drainage

   Ag pipe wrapped in geotextile at the base of the wall, a drainage blanket of gravel against the back, weep holes through the wall, and a discharge point where the water can go away. This is what makes a retaining wall last 60 years instead of 15.

4. 4. Rebuild or stabilise

   For walls past saving: full rebuild with correct footing, reinforcement and tie-backs engineered for the height. For walls with sound footings but drainage failure: drainage works alone may be enough. Helical bar stitching for masonry walls with cracks.

5. 5. Backfill properly

   Free-draining gravel against the drainage blanket, topsoil only at the top. Proper compaction. No heavy clay against the wall — that is what caused the problem first time around.