Why walls crack in Perth
Most cracked walls we're called to in Perth come down to the ground moving under the house. Reactive clays in the eastern and southern suburbs swell in winter and shrink in summer. Sandy blocks settle where the fill was poorly compacted, and leaking pipes and stormwater can wash sand out from under a footing. Rusted lintels and corroded wall ties cause cracking too, especially near the coast.
The shape of the crack tells us a lot. A stair-step crack through the mortar usually means movement in the footing. A crack that starts at the corner of a window points to a failed lintel or a weak spot over the opening. A crack that is wider at the top than the bottom tells us which way the wall is moving.
Signs your crack needs attention
- Cracks wider than about 2–3mm, or wide enough to fit a coin in
- Stair-step cracks running through the mortar joints
- Cracks above or below windows and doors, especially with rust staining
- Doors and windows that have started to stick or won't latch
- Cracks that reopen after they've been patched or painted over
- Walls that look like they're leaning, bulging or pulling away
How we repair cracked walls
We start with a free site visit to look at the crack, the building and what's causing the movement. Where needed we'll work alongside your structural engineer. Then we give you a written repair specification and quote.
Most cracks are repaired with the Helifix crack stitching system. We cut the mortar joints across the crack, then bond in stainless steel HeliBars with a cement grout. This ties the wall back together so it acts as one piece again. The joints are repointed to match, and render is made good over the top. It's quick, it doesn't disturb the house much, and once finished the repair is almost invisible.
If the ground itself is still moving, we deal with that first. That can mean underpinning the footing, fixing drainage, or replacing a lintel. Patching a crack without fixing the cause just means patching it again next year.
Recent wall crack repairs work
