Cracks are the most common reason a UK homeowner picks up the phone to a specialist, and the great majority turn out to be cosmetic. The British climate cycles through cold, wet winters and warmer, drier summers, and our housing stock is a mix of solid Victorian brick, post-war cavity walls, lath and plaster ceilings, and modern plasterboard. Every one of those materials moves a little with temperature and humidity, and most cracks are simply the visible record of that everyday movement.
The questions worth asking when you find a crack are always the same. How wide is it, where does it run, does it appear on both faces of the wall, and is it growing. A crack narrower than the edge of a 10p coin, sitting in a single internal wall and not visible from the outside, is rarely a structural problem. A crack that opens diagonally from a door or window frame, mirrors itself on the outside brickwork, and widens over a few months is a very different story and deserves a proper look.
Monitoring a crack at home costs nothing. Mark each end with a pencil line and the date. Photograph it against a tape measure or a coin. Check it again in a month, and after the next big change in weather. If the marks have not moved, you almost certainly have nothing to worry about. If they have, send the photos through and a vetted specialist will tell you whether it warrants a survey.
Should I fill a crack before showing it to a specialist?
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No. Leave it open. Filler hides the pattern, the width, and any fresh movement, all of which help us read the cause.
Are stepped cracks in brickwork always serious?
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Not always, but they are the pattern most associated with subsidence. Stepped cracks following the mortar joints in an external wall warrant a closer look, particularly if they are wider at the top.
How quickly should I act?
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There is rarely any need to panic. Subsidence develops over months and years, not days. Send a photo, get a sensible opinion, and act from there.
