What is it?
Cracks that run side-to-side along a wall, often following the mortar beds in masonry.
What does it look like?
[Insert Photos] Long horizontal lines, sometimes causing the wall to “bow” or lean slightly.
Common causes
1. Wall tie failure (corrosion)
2. Lateral pressure (e.g., soil pushing against a basement wall)
3. Roof spread
4. Thermal movement
How serious is it?
Rating: High Concern. Horizontal cracks often indicate a loss of structural integrity or significant external pressure on the wall.
How to tell which cause you have
Is the wall bulging? This suggests lateral pressure or wall tie failure. Are the cracks at regular intervals? Likely wall ties.
What should you do next?
Instruct a wall tie survey or a structural engineer immediately.
Typical repair options
Wall tie replacement, lateral restraints, or rebuilding sections of the wall.
Typical repair costs (UK)
£1,000 – £5,000+ per elevation.
Frequently Asked Questions
1. Is a horizontal crack always bad? Usually, yes.
2. What causes wall ties to fail? Moisture causing iron ties to rust.
3. Can roof spread cause this? Yes, if the roof isn’t tied correctly.
4. Is it covered by insurance? Sometimes, check your policy.
5. How do you fix a bulging wall? Usually with mechanical anchors.