Types of cracks in your home

Cracks in the walls of your home are never a pleasant sight. But while most are just a decorative nuisance and can be easily fixed, some can be a major cause for concern.

Cracks in the walls of your home are never a pleasant sight. But while most are just a decorative nuisance and can be easily fixed, some can be a major cause for concern.

Chris King
From the Home team
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Posted 20 DECEMBER 2019

What causes cracks in the walls of my home?

Most houses will experience cracks in the walls at some point. For the majority, it’s a natural occurrence caused by settlement:

  • In new builds and extensions, the foundations will settle under their own weight causing slight cracks in the walls.
  • In older houses, temperature changes and variations in humidity levels will cause the structure to sink and swell over time.
  • Newly plastered walls can often experience hairline cracks as they dry out.
  • If you live on a busy road, cracks in your house may be caused by road traffic vibration.
  • Timber window frames replaced with uPVC double glazing can cause cracks around the window if a supporting lintel isn’t fitted.

Do cracks mean subsidence?

While cracks caused by the above tend to be superficial and can be easily fixed, larger cracks could be the sign of serious structural problems, such as damage to the foundations and subsidence issues.

Larger cracks can be caused by:

  • Drainage damage and underground leaks.
  • Roots from nearby trees that spread into the foundations and suck away the moisture from the soil below your home.
  • Flooding and heavy rainfall, especially in clay soil areas.
  • Prolonged dry weather. The Association of British Insurers (ABI) reports that there was a 300% increase in subsidence-related claims due to the hot, dry weather experienced in July, August and September 2018, compared with the previous three months.

How can I tell if the type of cracks in my house are serious?

Cracks in your house can vary in length, width and direction. Typically, larger cracks (those bigger than 15mm in width) are a cause for concern and should be inspected by a structural engineer.

Subsidence cracks usually appear quite suddenly, rather than slowly over time. They are usually diagonal and wider at the top than at the bottom, and often found around doors and windows, according to the Association of British Insurers.

Types of cracks:

Negligible - hairline cracks less than 1 mm in width, which can be easily fixed by redecorating.

Slight - cracks between 1 and 5mm in width, which can be fixed with filler. Exterior cracks may need re-pointing.

Moderate - cracks between 5 and 15mm may need professional building work, including underlying repairs.

Severe - cracks up to 25mm wide could be a sign of structural damage and should be inspected and repaired by a professional.

Very severe - any crack above 25mm in width indicates serious structural damage and will need major repair work, which could include underpinning and rebuilding. A large crack running in a vertical direction can also be a tell-tale sign of structural damage.

If you’re worried about cracks in your house – no matter how large or small – seek the help of a building professional or structural engineer as soon as possible.

Are cracks in my home covered by my buildings insurance?

If cracks are caused by subsidence, then this should be covered by your buildings insurance. But it’s worth knowing that the excess on subsidence claims is often larger than for claims on the rest of your cover.  

If you do make a claim, your insurance provider will sometimes want to monitor the crack before deciding on how best to remedy the situation.

Cracks caused by natural settlement, thermal movement and lintel failure will be considered a maintenance issue and are most likely to be uninsured. Buildings insurance does not cover wear and tear and normal deterioration.

If in doubt, check your policy document to find out exactly what’s covered, or contact your insurance provider directly.

If you make a subsidence claim, you’ll also need to spell this out when comparing insurance or applying for insurance.

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