Print Friendly and PDF

Spot and repair cracks

A slight and natural movement of the building or a symptom of a wider problem? Find out whether the cracks in and on the outside of your home need further investigation.


Why do cracks appear?
No one likes to see cracks appearing in their walls, but most will be just surface disturbances of the plaster caused by your home expanding and contracting naturally (or breathing as it is sometimes known). New homes can be plagued in the early months of occupation by minor cracks caused by the home settling. For the most part these cracks, though often unsightly, are harmless and can be decorated over. However, if the cracks persist in reappearing or get noticeably wider, it is worth getting to the bottom of what is causing them.

What does a crack tell you?
A crack is actually the visible symptom of a possible problem, and not the problem in itself. And its seriousness and diagnosis depends on the materials with which your walls are made. Serious cracks - such as one in a brick or block wall that has been filled more than once, but keeps reopening - may signify a serious problem.

Often, there is no one definitive cause for a crack. Sometimes, the minor changes in the temperature and moisture within building materials can be enough to cause hairline fractures in a surface. Vibrations from traffic, particularly if your house is over a ridge, can cause problems, too. The most likely are causes of cracks include shrinkage of wall materials (such as timber or concrete blockwork) and expansion (of clay bricks). However, cracks can also be caused by corrosion (of wall ties or lintels) and foundation movement (including subsidence, heave or settlement).





Problem solving

Hairline cracks
Hairline cracks and those measuring up to 5mm in width can be filled and painted over with ease. But if more than one crack appears in the same room, or a single one measures more than 5mm wide, you should seek professional advice.

Cracks that widen
While most cracks will prove to be benign, it is worth monitoring them for any signs of growth. If you have a digital camera, take a photograph every week or so and compare your most recent image with the first. This might come in handy later if you need to make a claim with your insurance company.

Cracks indoors and outdoors
If a crack appears suddenly and progresses rapidly, even showing evidence of progressing to the exterior of the building then you will need to consult a professional because this will almost certainly be a sign that your home's foundations are moving.

Cracks in brickwork
Cracks in brickwork or loose pointing (mortar) are a different matter. They can be caused by the elements acting on flaws within the brick, but they can also be caused by a shift in the building's weight.

Cracks in window and door frames
Look out for cracks in window and door frames which may be symptomatic of extra weight being placed on lintels. If at the same time doors begin suddenly to stick you should seek professional advice immediately.

Cracks caused by overloading
Double-storey homes or loft conversions can cause stresses on a home if not carried out and assessed professionally. Installation of a luxury bathroom in a loft space, with all the necessary fixtures fittings and trimmings can add to the burden on structural brickwork.

Check before you buy
Movement beneath a house can leave a property seriously structurally unsound. But what should you be wary of and what precautions can you take?

* Beware of homes built on landfill sites and mine shafts where collapsing tunnels could bring disaster.

* By far the most common risk is to homes built on clay soil, which shrinks and swells with changes in the weather.

* Get a thorough land search and environmental report to detect any dangers before it’s too late.