Canterbury & Kent

Cracks in Your Walls? What They Mean and When to Worry

Get a Fixed-Fee QuoteCall 0204 579 8270

You noticed it while moving furniture, or repainting, or simply glancing up the stairs: a crack in the wall that you are fairly sure was not there before. Most wall cracks are harmless — but some are the first visible sign of subsidence, failed lintels or structural movement, and the difference is impossible to judge from worry alone. This guide explains what different cracks mean, which ones you can ignore, and when it is worth getting a professional opinion.

Hairline cracks: usually nothing

Fine, threadlike cracks in plaster — especially around new plasterwork, ceiling corners or above doors — are usually shrinkage or seasonal movement as the building warms, cools and dries. They reopen after redecorating and they are annoying, but they are cosmetic. Fill, repaint, and keep half an eye on them.

Cracks that deserve attention

Some patterns tell a different story. Diagonal cracks stepping through brickwork mortar joints, cracks wider than a five-pence coin (about 3mm), cracks that keep growing after repair, cracks around window and door openings that make frames stick, and cracks that appear suddenly after a dry summer — particularly on clay soils like much of Kent — can indicate subsidence, heave or overloaded openings. External cracks mirrored inside on the same wall are the strongest signal of genuine movement rather than surface plaster problems.

What is actually causing it?

Around Canterbury and east Kent the usual suspects are shrinkable clay subsoils drying and rewetting with the seasons, street and garden trees drawing moisture from beneath foundations, leaking or collapsed drains washing out supporting ground, and older openings where a timber lintel has quietly failed. None of these announce themselves — the crack is often the only clue you get.

When to call a surveyor

If a crack is wider than 3mm, growing, stepped through brickwork, or paired with sticking doors, sloping floors or external evidence, an inspection is worth far more than months of wondering. A structural crack assessment identifies the cause and tells you plainly whether it matters; where ground movement is suspected, a subsidence survey takes it further with monitoring and drainage checks. If you are buying a property with visible cracking, a full building survey prices the risk before you commit.

Most inspections end in reassurance — genuinely. But the ones that do not are the ones where early advice saves five-figure sums. If a crack is bothering you anywhere in Canterbury or Kent, send us a photo or call 0204 579 8270 and a chartered surveyor will tell you honestly whether it needs a closer look.