Cracks in brick walls are common in Sydney, where reactive clay soils swell and shrink with the seasons. Many are minor. Some are a sign the building is moving. Knowing the difference, and repairing the crack properly, saves a lot of money later.
What causes cracks in brickwork
- Footing movement on reactive clay, poor fill or leaking drains and pipes.
- Corroded steel lintels over windows and doors, which expand as they rust and crack the brickwork above.
- Failed wall ties in cavity walls, letting the outer skin move independently.
- Tree roots drying out clay soil near footings.
- Thermal and moisture movement in long walls without control joints.
Which cracks should worry you?
As a general guide, hairline cracks under about 1mm are often cosmetic. Cracks that are wider than a few millimetres, getting wider, running diagonally from window and door corners, passing through bricks rather than around them, or accompanied by sticking doors and windows deserve a proper inspection. Our guide to whether cracks in walls are serious goes into more detail.
What is brick stitching?
Crack stitching uses helical stainless steel bars bonded into slots cut in the mortar joints across the crack. The bars tie the brickwork on each side back together and spread load across the crack. The crack itself is then filled with a matching mortar. Done well, the repair is close to invisible.
How stitching is done
- Slots are cut into the bed joints across the crack, usually every few courses.
- The slots are cleaned and partly filled with a bonding grout.
- Helical bars are pressed in, extending well past the crack on each side.
- More grout is added, then the joints are repointed to match.
- The crack is filled or the cracked bricks replaced.
Fix the cause first
Stitching restores the strength of the wall but does not stop the movement that caused the crack. If a lintel has corroded, it needs replacing. If footings are moving, drainage, tree management or underpinning may be needed. For significant cracking, an engineer should specify the repair.
Brick repairs in Sydney
We diagnose and repair cracked brickwork across Sydney, from single cracks to full structural repairs. See our brickwork repair service.
Frequently asked questions
Does crack stitching work on all brick walls?
It works on most solid and cavity brick walls. The cause of the crack must also be dealt with, and significant cracking should be designed by an engineer.
Will the repair be visible?
Done properly, with mortar matched in colour and texture, crack stitching is very hard to see once finished.
Should I fill cracks in brickwork myself?
Filling a crack hides it but does not restore the wall or fix the cause. Get it assessed first, especially if it is wide or growing.
