Subsidence or just settlement? Reading the cracks in your walls

Settlement is normal

Every building moves a little as it beds in and as the seasons change. Fine hairline cracks in plaster, cracks that open and close slightly with the weather, and small cracks at the junctions of different materials are usually settlement — cosmetic, stable, and no cause for alarm.

What subsidence looks like

Subsidence is the ground beneath a foundation moving, and it leaves a different pattern. The cracks are typically diagonal, wider at the top than the bottom, run through brick as well as mortar, and appear inside and outside in the same place. They tend to keep growing rather than stabilising.

• Diagonal cracks, wider at one end, often near corners and openings
• Cracks wider than a ten-pence coin that keep growing
• The same crack visible inside and outside the house
• Doors and windows that suddenly stick or will not close

What to do

If the signs point to subsidence, the cause has to be dealt with first — often a leaking drain, a thirsty tree, or poor ground — usually alongside your insurer and their engineer. Only once movement has stopped do you rebuild.

Where the cracks are stable, the repair is often crack stitching with helical bars rather than anything dramatic. Send us photos and we will tell you honestly which camp yours falls into.