Settlement cracks explained

Every new build home moves. Timber dries, plaster cures, mortar sets and the structure quietly settles onto its foundations during the first eighteen to twenty four months. The visible result is hairline cracking, almost always cosmetic, almost always misunderstood.

This guide explains what's normal, what isn't, and how to tell the difference before you spend money on a survey you don't need.

A modern home contains tonnes of water. Wet plaster, screed, mortar and timber all release moisture as they dry, and the materials around them shrink by tiny but visible amounts. The first heating season accelerates this. Central heating pulls moisture out of walls and ceilings within weeks of moving in.

The result is shrinkage cracking: thin, straight, often following the line of a stud, joist, or plasterboard joint. It's a sign the house is behaving exactly as it should.

Hairline cracks under 1mm wide. Cracks above doorways and windows that follow the corner of the frame. Cracks along the line between ceiling and wall. Cracks at the join between two sheets of plasterboard. Cracks where staircase strings meet plastered walls.

These are filler and paint jobs, best left until the second decorating cycle once the house has finished moving.

Diagonal cracks wider than 2mm, especially around window or door openings. Cracks that step through brickwork outside. Cracks that re-open within weeks of being filled. Cracks accompanied by sticking doors, sloping floors or visible movement in the structure.

These warrant a structural opinion, not panic, but a properly qualified eye.

Wait until the end of your second heating season before redecorating. Photograph any crack wider than a £1 coin with a ruler held against it and a date in the frame. If you're unsure, send the photographs to us. We'll tell you honestly whether it's cosmetic or worth investigating.