Structural and building problems

A crack has appeared in a wall and you want to know whether it is cosmetic or structural.

The beam over a window or door has cracked, sagged or dropped, and the brickwork above it has moved.

Diagonal cracks, sticking doors and a floor that has dropped — the pattern that suggests the ground under the house has moved.

A dark or discoloured patch on the inside face of an external wall that comes and goes with the weather.

A vertical crack has opened along the line where a new extension meets the original wall.

A marble rolls across the bedroom floor, or a wardrobe no longer stands level against the wall.

You are selling, remortgaging or insuring, and there is no paperwork for an extension, a removed wall or a loft conversion.

A downstairs chimney breast has been taken out and the brickwork above it appears to be hanging with nothing under it.

Paving, decking or soil has been built up the outside wall, burying the black line of the damp proof course.

Fine cracks have appeared in a house that is only a year or two old, usually at ceiling and wall junctions.