Cracks in walls: when to worry and when not to
Not every crack is a problem. How to tell a harmless plaster crack from a sign that something is moving, and what to do next.
By Redbay Group ·
Most cracks are cosmetic
Fine, hairline cracks in plaster are common, especially in the first year as the plaster dries and shrinks. They usually run in random directions, do not grow, and can be filled when the house is next painted.
Signs that need a closer look
Call a professional if you see any of these:
- Cracks wider than a coin's edge, or that keep getting wider
- Diagonal cracks running from the corners of doors and windows
- Stair-step cracks following the joints in block or stone walls
- Doors and windows that suddenly stick or will not close
- Cracks in the floor slab, beams or columns
Common causes
Bigger cracks usually point to movement: soil settling under the foundation, water collecting near the walls, or a beam or slab carrying more load than it was designed for. The crack itself is a symptom. The cause is what needs fixing.
What to do
Photograph the crack next to a ruler and note the date. Check it again after a few weeks. If it has grown, or matches any of the signs above, have a structural engineer inspect it before any repair. Filling a moving crack only hides the problem.