Wall leaning or collapsed? Here is what to do right now
Updated October 2026
A leaning retaining wall is a loaded structure that has started to lose. Sometimes it loses slowly over years, sometimes it goes in one wet weekend. If your wall has moved, especially after heavy rain, treat it as live until someone qualified says otherwise. Here is what to do, and what not to do, before a builder gets there.
Do this first
Keep people away from the toe of the wall. The toe is the strip at the base where a collapsing wall and the soil behind it will land. Keep kids, pets and foot traffic off it, on both sides of the wall if it is on a boundary.
Move cars. If a vehicle is parked below the wall, or parked above it where its weight adds load, move it now while you safely can.
Fence it off if you can. Star pickets and tape, chairs and a rope, anything that stops someone wandering into the fall zone, especially at night.
Photograph everything. Wide shots, close-ups of cracks and bulges, the gap at the top, water staining, the date visible if possible. Take the same shots again tomorrow. Insurers and builders both need this record, and repeat photographs prove whether the wall is still moving.
Turn the water off. Shut down any reticulation watering the ground behind the wall and redirect any downpipe discharging near it. Water pressure is almost always what pushed the wall in the first place.
Note what changed. Heavy rain, a new garden bed, recent excavation nearby, a leaking pipe, a load parked above. The cause matters for the fix and for insurance.
Do not do this
Do not excavate at the base. Digging at the toe to relieve or inspect a leaning wall removes the resistance that is keeping it up. This is the fastest way to turn a lean into a collapse, with you standing in the fall zone.
Do not prop it with whatever is handy. A sleeper angled against a moving wall is not a repair, it is a trap for the next person who walks past.
Do not drill it to let the water out. Holes in a failing wall relieve very little and can let soil wash out through them.
Do not start demolition until your insurer has been told and the wall has been assessed. Pulling the wall apart can complicate a claim and can release the slope suddenly.
When a lean means replace
A small, old, stable lean on a structurally sound wall can sometimes be repaired, usually by fixing the drainage and reducing the load. But some signs mean the wall is finished: posts snapped or rotated in the ground, timber rotted through at soil level, a lean you can measure growing week to week, bulging across several bays, or soil escaping through the face. Past that point, money spent patching is money you will spend again on the rebuild. The builders we refer will tell you which side of the line your wall is on and quote accordingly, repair via retaining wall repairs or replacement in concrete sleeper, block or limestone.
Why this happens up here
The Perth Hills is hard country for retaining walls, and the reason is in a council document. The City of Kalamunda records in its Local Planning Strategy that reticulated sewerage is constrained in the Hills because hard granite sits close to the surface and is costly to dig through. Rock that close up means water cannot keep draining down. It runs sideways along the rock and arrives behind your wall. The Shire of Mundaring names perched water tables and heavy soils as Hills constraints for the same reason.
Add a sloping block loading the wall from above, and decades-old walls built with no ag-pipe behind them, and wall failures across the Hills come in waves after a wet spell. If yours moved in the last rain, you are not the only one, and getting into the assessment queue early matters. Our retaining wall drainage page explains the mechanics.
The approval point, before you rebuild
Replacing a wall in the same place does not automatically mean no permit. In WA a retaining wall is exempt from needing a building permit only where it retains no more than 500mm of ground, is not tied to other building work or to holding up the land next door, and is not work of a kind that affects adjoining land. All three have to be true. A wall on or at a boundary is dealt with separately under the Building Act and needs the neighbour's consent or another authority whatever its height, and that is very often the wall that has failed.
Building and Energy has disciplined a builder for negligent conduct after part of a retaining wall project at a Perth property was carried out without a building permit and encroached on neighbouring land without consent. Confirm what your rebuild needs with the Shire of Mundaring, the City of Kalamunda, the City of Swan or the City of Armadale, whichever is your permit authority. On who may carry out the work, WA draws the line by how the work is classified under the building legislation, not by a dollar threshold you can apply to your own job, and the position for a standalone retaining wall is not something to take from a website. Ask any builder what registration or licence they hold and verify it with Building and Energy, and ask your permit authority what your wall requires.
How we help
Perth Hills Retaining Walls is a referral service. Tell us what the wall is doing through the form, photographs help a lot, and we pass it straight to an experienced, insured local builder who works your suburb. They assess it, tell you honestly whether it is repair or replace, and quote for free.
Frequently asked questions
Is a leaning retaining wall an emergency?
Treat fresh movement as urgent, especially after rain, above a path or driveway, or on a wall taller than about a metre. An old stable lean is less urgent but still worth an assessment, because leans rarely improve on their own.
Will insurance cover my collapsed retaining wall?
It depends on the policy and the cause. Many policies distinguish storm damage from gradual deterioration, and some exclude retaining walls specifically. Photograph everything, note the trigger event, and call your insurer before any demolition.
Can I dig the soil away to take pressure off the wall?
No. Removing soil at the base removes the wall's resistance and can bring it down on you. Reduce water instead, keep people clear, and leave excavation to the builder with the right gear and a plan.
How quickly can someone look at it?
Send the request through the form with photographs and it goes straight to a local builder who works your suburb. How soon they can attend depends on their own workload, which spikes after a wet spell, so get the request in early rather than waiting to see whether the wall settles.