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 are a major cause for concern. Read on to find out more. 

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 are a major cause for concern. Read on to find out more. 

Chris King
From the Home team
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Posted 7 JULY 2021

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, like damage to the foundations or 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 moisture from the soil below your home. 
  • Flooding and heavy rainfall, especially in clay soil areas. 
  • Prolonged dry weather. It was widely reported in 2018 that there was a 300% increase in subsidence-related claims due to the hot, dry weather experienced in July, August and September, compared with the previous three months. 
  • Poor foundations – some older buildings have much shallower foundations than most modern buildings, making them potentially less stable. Poor materials can also allow buildings of any age to shift. 
  • Mining – in some parts of the UK, properties can experience damage because of local underground mines, including those long-disused. 
  • Lintel failure – where support for the brickwork above the opening of a window or door is poor or non-existent. It’s characterised by diagonal cracks, sometimes mistaken for subsidence. 

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’re usually diagonal and wider at the top than at the bottom, and are often found around doors and windows. Lintel failure may need to be ruled out first, as these types of cracks can look similar. 

Types of cracks:

Negligible – hairline cracks less than 1mm 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. Subsidence cracks can be wider at the top than the bottom and are likely to be able to be seen from outside the property as well as inside.

Vertical cracks – these kinds of small cracks often appear in plastered walls in new properties. They can happen when the plaster expands in humidity and shrinks as it dries. Instead of filling and repainting them straight away, you should wait a while before filling the cracks and repainting, as more could likely appear. If vertical cracks are wider than 0.5cm, there could be a more serious cause which should be investigated. 

Diagonal cracks – these can look, in shape, like a set of stairs going along your wall. They could be a sign of structural movement and should be taken seriously. 

Some diagonal cracks around doors and windows can appear because the lintel above is missing, weak or badly installed. Ideally you should seek expert help to determine the cause of the problem. 

What should I do if I’m worried about cracks in my property?

If you rent, you should get in touch with your landlord as soon as possible. Leaseholders should contact the freeholder about the problem – as they’ll be responsible for the fabric of the building. In both cases, the owner should have buildings insurance and be able to make a claim on their policy, where necessary. If the cracks are just in the plasterwork, you may be responsible for these, so check your lease or rent agreement. 

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

One of the first things they’re likely to do is monitor the cracks in your home to see if any movement has now stopped, or if it’s still moving and requires further investigation. This can be a simple procedure, where some removable studs or gauges are placed either side of the crack, and changes in position arw monitored over time. Smart wireless monitors can also continuously monitor the crack and temperature, but these may be more expensive.  

Are cracks in my home covered by my buildings insurance? 

For homeowners, 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, or normal deterioration. 

If the cracks are a result of subsidence caused by an escape of water, like leaky drains, your claim for loss or damage will usually be considered under the ‘escape of water peril’ clause of your insurance policy at first. This could have the advantage of being subject to a lower policy excess. But there may be a specific exclusion for subsidence damage under this section of the policy – in this case, you’ll have to claim under the subsidence rules which will usually have a higher excess. 

If the subsidence is due to mining, there may be a claim against the Coal Board or mine owner, for example. You’ll need to discuss with your insurance provider whether you’ll have to claim from them directly, or if the insurance company will do it on your behalf. 

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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Frequently asked questions

What are the different types of ground movement?

When dealing with claims, one of the first things insurance providers will look at is the probable cause of the ground movement that’s resulted in the damage, as this could make a difference as to whether a claim is paid or not. 

There are four main causes, as defined by the Financial Conduct Authority (FCA): heave, landslip, settlement and subsidence. 

Definitions of ground movement types:

  • Heave – Upward movement of the ground beneath a building as a result of the soil expanding. 
  • Landslip – Downward movement of sloping ground. 
  • Settlement (also known as consolidation or compaction) – Downward movement as a result of soil being compressed by the weight of a building within 10 years of construction. 
  • Subsidence – The ground beneath a building sinks, pulling the property’s foundations down with it. It usually occurs when the ground loses moisture and shrinks, which can be caused by prolonged dry spells. It may also be caused by trees and shrubs, which can absorb significant volumes of water from the soil.  

Will claiming for a crack affect my insurance?

Yes, if you’ve claimed for subsidence you could well see an increase in your premium come renewal time. That’s because customers who’ve claimed for subsidence once are more likely to make another claim in future. Your no-claims discount or bonus, if you have one, may also be affected.

Can I claim for cracks in my outbuildings?

It will depend on your insurance policy. Home insurance policies differ in how they define the main residence. Some will include outbuildings and garages as part of the home, others won’t, so you’ll need to check the policy wording. 

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