House cracking: what you need to know

Much domestic cracking is caused when reactive clays in the soil below the house dry out and become moist again. These changes in the soil cause upheaval of the footings and, therefore, cracks in the house.

Are there any other causes?

Different building materials behave in different ways. For example, bricks tend to expand, concrete tends to shrink and timber tends to warp. This, combined with the fact that these materials are often interconnected, can make many homes vulnerable to cracking.

Cosmetic or structural cracking?

An engineer can determine whether the cracking in your home is cosmetic or structural. If it's cosmetic, all that's usually required is filler and paint, but structural cracking may require more extensive (and expensive) work, such as underpinning of the footing.

Getting to the root of the cause

Before embarking on any repairs it's important to determine what has caused the cracking. The root cause may be something fairly simple – that is, something unrelated to reactive clays or building materials ­­– so the cracking might be fairly easy and inexpensive to fix.

The process

If you notice cracks in your house, call in an engineer. They can determine the cause of the cracking then advise what, if anything, needs to be done. If work does need to be carried out, the engineer should prepare a 'scope of works' document for the homeowner to present to a builder or contractor.

Can anything be done to prevent cracking?

If the underlying cause of the cracking is reactive clay, it might be difficult to halt it entirely, but you can lessen the chance of it happening by keeping the moisture content of the soil around and under the house stable. This might mean placing plants, taps and drains away from the house.

Talk with a builder in your area and discover how you can prevent house cracking: