What Causes Cracks on Plaster Ceiling?

Spotted a crack in your ceiling? Some are minor, while others need a closer look. Here are the clues worth noticing before you reach for the filler.

A fine line across a plaster ceiling can look worrying, especially if you have only just noticed it. The good news is that small cracks are common in homes. Plaster and plasterboard joints can move slightly as a building dries, warms up or responds to changes in moisture.

Not every crack is cosmetic, though. What matters is the wider picture: how it has changed, whether the ceiling is sound and whether there are any signs of a leak or movement elsewhere.

Common reasons ceilings crack

Hairline cracks and shrinkage

As new plaster dries, or as different building materials expand and contract, fine cracks can appear. Older decorative finishes and repeated painting can also develop surface cracking. An isolated, stable hairline crack in an otherwise sound ceiling may only need a suitable repair once its cause is understood.

Straight cracks along plasterboard joints

Some cracks follow the joint between two plasterboard sheets. Movement, the way a joint was taped or finished, and changes in temperature or humidity can all contribute. The location offers a clue, but it is not a diagnosis on its own.

Cracks where the ceiling meets the wall

Small gaps at the edges of a ceiling may result from normal movement between different materials. If a crack is widening, continues into the walls or appears alongside other changes in the property, it deserves further investigation.

Stained or discoloured cracks

A brown mark, damp patch, blistering paint or peeling finish can indicate water reaching the ceiling. The source might be a pipe, bathroom fitting or roof defect. Fixing the visible crack without finding the moisture source is unlikely to solve the problem.

If there may be a plumbing leak, our plumbing team can discuss the next step. Roof defects and structural concerns may need other specialists.

Wider, spreading or irregular cracks

Several cracks appearing together, cracks that are growing or a ceiling that has become uneven can point to a problem with the plaster, its fixings or the structure behind it. A spiderweb pattern or a straight line is not enough to determine how serious the problem is; the building's age, construction and recent changes all matter.

When should you be concerned?

Arrange a suitable professional assessment if a crack is getting longer or wider, is accompanied by damp, reappears repeatedly after repair, or coincides with movement elsewhere such as newly sticking doors or cracking in walls.

A sagging, bulging, loose or rapidly deteriorating ceiling needs urgent attention. Keep people clear of the affected area and do not press on the plaster or attempt a cosmetic repair. Seek advice promptly from a competent building surveyor or appropriate building specialist; if there appears to be an immediate risk of collapse, do not use the room until it has been made safe.

Can you repair a cracked plaster ceiling?

Often, yes. Where a small crack has been assessed as a surface defect and the ceiling is secure and dry, a decorator or experienced handyman may be able to prepare, fill and redecorate the area. A recurring joint crack may need more than a coat of paint. Loose plaster, persistent damp or possible structural movement should be dealt with by the relevant specialist first.

Older lath-and-plaster ceilings can behave differently from modern plasterboard. If plaster is coming away from the ceiling or there are signs of deterioration, seek someone familiar with that construction rather than trying to patch it yourself.

Will home insurance cover ceiling cracks?

That depends on the cause and the policy. Routine wear and decorative maintenance may be treated differently from sudden insured damage. If you suspect a leak, movement or another event that may give rise to a claim, check your policy and contact your insurer before authorising major repairs.

What should you do first?

Make a note of when you spotted the crack and whether it has changed. A dated photograph can help you explain the problem to a professional. Look for water staining or visible movement, but do not disturb loose plaster or investigate from an unsafe position.

Once the cause is understood, HandyExperts can help arrange suitable minor making-good work or relevant plumbing repairs. Call us on 0330 912 2323 and tell us what you've noticed.