What is it?
Cracks that follow the zig-zag pattern of the mortar joints between bricks or blocks.
What does it look like?
[Insert Photos] A “staircase” pattern climbing up or down a brick wall.
Common causes
1. Foundation settlement
2. Subsidence
3. Lintel failure (if near an opening)
4. Thermal movement
How serious is it?
Rating: Medium to High Concern. If the crack is thin and follows mortar, it may be settlement. If it’s wide or cuts through bricks, it’s likely subsidence.
How to tell which cause you have
Check the width. Hairline is usually settlement. Over 3mm usually indicates subsidence or significant movement.
What should you do next?
Measure the width and monitor. If it continues to grow, call a structural engineer.
Typical repair options
Repointing, helical bar reinforcement (crack stitching), or underpinning.
Typical repair costs (UK)
£300 (repointing) to £10,000+ (underpinning).
Frequently Asked Questions
1. Is stair-step cracking normal? Minor settlement is common.
2. Does it mean my foundations are failing? Not always, but it’s a sign.
3. Can I just repoint it? Only if the movement has stopped.
4. Why is it zig-zag? It follows the path of least resistance (mortar).
5. Is it common in old houses? Yes, due to shallow foundations.