Repair a crack in a ceiling
Save £80–150 today
1 hour + drying · Beginner · Saves £80–150 vs a decorator
Last updated: March 2025
Before you start
Most ceiling cracks are cosmetic — caused by normal building movement and temperature change. Hairline cracks that stay the same size over time are safe to fill and paint.
Work from a step ladder, not a chair. You need both hands free and a stable base.
Tools needed
- ✓Step ladder or stable platform — to reach the ceiling safely
- ✓Filling knife (4-inch) — to apply and smooth the filler
- ✓Fine sandpaper 240-grit — to finish the repair
- !Flexible filler or fine surface filler — buy: buy: £4–8 — flexible filler is better for cracks that may move slightly
- !Ceiling paint — buy: buy: £6–12 — white matt is standard for ceilings
Rake out the crack
Use the tip of your filling knife or a screwdriver to gently rake out any loose plaster inside the crack. A clean crack accepts filler better than one with crumbling edges.
Where beginners go wrong
Painting directly over unfilled filler without a primer coat — the repair shows through as a circle.
Using a rigid filler on a crack that is still moving — it will crack again within weeks.
Not raking out loose material — filler applied over crumbling plaster falls out.
Stop and call a decorator if...
The crack is wider than 5mm or runs diagonally from a corner — may indicate structural movement
The crack keeps coming back after filling — the building is still moving
Large sections of ceiling plaster are loose or bowing downward — do not use that room until it is assessed
Cost breakdown
What you just learned
You can now assess whether a ceiling crack is cosmetic or structural, and repair the cosmetic type to a professional standard.
What this unlocks
This technique is identical for wall cracks. Once you can repair a ceiling, you can repair any surface before painting.
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⚠️ Watch out if you rent
Report ceiling cracks to your landlord in writing, with a photo. Cosmetic hairline cracks are normal wear and tear. Larger cracks may indicate a problem the landlord needs to investigate.