Retaining walls Northern Beaches

Often not, if the wall is no higher than 600 mm, sits about 1 m from the boundary and doesn't send water onto the neighbour's land. Taller walls, walls on the boundary, stacked walls less than 2 m apart and walls near the lagoon or Pittwater usually need approval. We check this at the site visit.

Sydney cost guides put a wall about 1 m high at roughly $350 to $900 a metre in concrete sleepers or block, with timber sleepers from about $230 a metre (What's The Damage? and Yakka Labour, October 2026). Sandstone and engineered walls cost more. Height, rock or sand underfoot, stairs-only access and drainage change the price. Your price is set at the free site visit.

Usually water. Without drainage behind the wall, wet soil pushes against it after heavy rain. Other common causes are rotting sleepers, tree roots and walls built too thin for their height. A leaning wall is usually rebuilt with drainage rather than propped up.

Yes. Most walls on stairs-only blocks are built by hand. Where a small tracked machine fits down the side of the house, we use one for the digging.

Sandstone and concrete sleeper walls with good drainage last for decades. Treated pine has a shorter lifespan, especially in wet ground. Drainage matters as much as the material.

Sometimes repaired, more often replaced. A short run that has moved a little, with sound blocks or sleepers, can be dug out behind, drained and reset. A wall that is cracked through, bulging or rotten at the posts usually comes down and is rebuilt with drainage.

There is no simple rule. The NSW Dividing Fences Act doesn't count a retaining wall as a fence unless it holds up the dividing fence. Responsibility often follows who changed the ground level. Agree it with your neighbour in writing before work starts; Legal Aid NSW explains the options.

Yes. Roots of a large tree close to a wall can lift its footing, crack blocks and push sleepers out of line. A new wall is set back from the trunk or bridged over the big roots, rather than cutting roots the tree depends on.

Usually water moving through it. Salts dissolved from the soil, mortar or concrete dry on the face as a white crust, called efflorescence. It brushes off when dry, but it shows water is passing through the wall, so check the drainage behind it.

Often, yes. Sound blocks are lifted, cleaned and relaid on a new footing with gravel and an ag pipe behind. Cracked, soft or flaking blocks are swapped for new sandstone chosen to sit close in colour, and the old stone can go into steps or edging.

Often, for walls over about 1 m, walls holding up a driveway, a building or the neighbour's land, and walls on slopes the council maps for landslip risk. The engineer sets the footing, drainage and any steel. We tell you at the site visit whether yours needs one.