If you’ve spotted a crack, find out whether it might be subsidence or one of the other far more common – and much less sinister – reasons that cracks form.
Although some cracks are warning signs that the ground beneath a building is shifting and causing structural damage, most are harmless.
Common causes of minor cracks include:
All new buildings – or new extensions to homes – settle downwards under their own weight. This can cause cracking without any threat to the structure.
Usually, settlement cracks appear at weak points, like around windows.
It can take up to 10 years for a building to settle, so you can expect some minor cracks to appear in new builds for quite some time.
All buildings, new and old, expand in the heat and contract in falling temperatures. You may have even heard creaks or snapping sounds as these movements occur.
Thermal cracks caused by this sort of movement are minor and easily repaired.
In newly-built homes, moisture in building materials like wood, concrete and mortar dries out over several months. This results in some shrinkage, which can lead to cracks, usually near ceilings and floors.
In homes old and new, cracks can appear when building materials expand and shrink depending on how much moisture is in the air.
Materials expand as they absorb the water vapour that’s expelled in our homes when we take baths and showers, or boil kettles and cook, for example. Then they shrink as they dry out when it’s warm outside or when the central heating is on.
Cracks can also be caused by:
Minor cracks that measure no more than 2mm are usually nothing to worry about and will have no effect on the safety and stability of your property. You can easily check the width of cracks with a measuring tape.
But you should investigate further cracks that:
These sort of cracks could be a sign of structural damage and subsidence.
Subsidence happens when the ground beneath a property erodes and moves downwards.
As the ground sinks, it pulls the property’s foundations down with it, damaging its structure and causing cracks.
Heave, on the other hand, is when the ground moves upwards, or swells, causing a property to lift. It’s less common than subsidence.
Heave and subsidence can occur when soil gets too wet due to flooding, or too dry due to excessive periods of drought.
These type of ground movements tend to happen in:
As well as wide cracks appearing, signs of subsidence can include:
In a newly-built home, you can help to keep cracks at bay by allowing building materials to dry out gradually so that shrinkage is not too sudden.
Try leaving window vents open to allow for natural evaporation of moisture and avoid cranking up the central heating too high as excessive heat can speed up the drying process and cause cracking.
If you live somewhere that’s prone to subsidence issues – such as a clay soil area – there are some things you can do to try to help prevent the problem.
When you next decorate, you can easily repair minor cracks using a filler, then lightly sanding before applying paint.
If you suspect subsidence, you should contact your insurer.
They may send out a building specialist or surveyor to take a look.
The specialist might want to place monitors onto cracks to check for ongoing movement and to assess the ground below the foundations.
If movement of your home has stopped, then repairs to damage can go ahead.
If movement is ongoing and is causing major structural damage then you may need to have your home underpinned. This involves lifting, re-levelling and strengthening the ground underneath the building.
Small, hairline cracks are normal as a newly built property settles, or as any home ages and is lived in.
Such minor cracking is a cosmetic problem, and any repairs needed won’t be covered by buildings insurance.
Cracks that form as the result of subsidence, though, are usually covered by an insurance policy.
This is true only if your home has not suffered subsidence in the past (though there are some specialist insurance policies that will cover properties with subsidence history.)
Your buildings insurance policy will cover the cost of repairing damage to the structure of your home that occurs as the result of subsidence, including the repair of cracks.
It won’t normally cover the cost of preventing further subsidence and movement of your home though.
Some policies offer to meet the cost of your accommodation should you need to move out of your home if it needs extensive repair.
Subsidence claims usually come with an excess in the region of £1,000.
Premiums and excesses can increase after you’ve made a subsidence claim with your insurer, especially if it’s still at risk of further movement.
Some companies won’t insure you at all if your home has had subsidence issues as they see it as too much of a risk.
You may need to shop around for specialist insurers who will cover you.