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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.

Written by
Anna McEntee
Insurance comparison expert
Reviewed by
Andy Webb
Insurance Expert
Last Updated
15 JANUARY 2024
7 min read
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What causes cracks in the walls of my home? 

It’s likely your house will experience cracks in the walls at some point. Most of the time, it’s perfectly normal. Here are some of the common causes of cracks in homes:

  • 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 shrink and swell over a prolonged period of time.

  • Plaster shrinkage. 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?

Cracks caused by the above tend to be superficial and can be easily fixed. But anything larger could be the sign of serious structural problems, like damage to the foundations or subsidence issues.

Larger cracks can be caused by:

  • Water 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
  • Poor foundations – older buildings can sometimes have much shallower foundations than 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, local underground mines, including those long-disused, can cause damage.
  • Lintel failure – where support for the brickwork above the opening of a window or door is poor or non-existent. Look for diagonal cracks, sometimes mistaken for subsidence.

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

No wall crack is the same. They can vary in length, width and direction. Typically, larger cracks (those bigger than 15mm in width) are a cause for concern, as they could point to structural issues. You’ll want to get these 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.

Different types of cracks:

Negligible — hairline cracks less than 1mm in width. These can be easily fixed with a bit of DIY. 

Slight — minor cracks between 1mm and 5mm in width, which can be fixed with filler. You might need to repoint exterior cracks.

Moderate —  cracks between 5mm and 15mm may need professional building work and there might be 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 a serious issue with the structural integrity of the home and could require major foundation repair work, which could include underpinning and rebuilding. Subsidence cracks can be wider at the top than the bottom and are likely to be visible from the external walls.

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 appear. If vertical cracks are wider than 0.5cm, there could be a more serious cause, which should be investigated.

Horizontal cracks — these could be the result of structural movement. These sorts of foundation problems should be taken seriously.

Diagonal cracks — these are also known as stair-step cracks, like a set of stairs going along your wall. They could be a sign of structural movement. Take them seriously.

Some diagonal cracks around door frames and windows can appear because the lintel above is missing, weak or badly installed. It’s best to get expert help to determine the cause of the problem.

Ceiling cracks — these could be caused by several things, including plaster shrinkage, damp and structural movement. Because of this, it’s best to have it inspected by a professional. Repairing a drywall ceiling isn’t as easy as repairing a crack in an internal wall, so you should consider getting a professional to repair it to a good standard.

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

If you rent, talk to your landlord as soon as possible. Leaseholders should contact the freeholder about the problem – as they’ll be responsible. 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 – 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 are 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, cracks caused by subsidence should be covered by your buildings insurance. But you’ll have to pay an excess, which 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.

But cracks caused by natural settlement, thermal movement and lintel failure will be considered a maintenance issue - and because buildings insurance doesn’t cover wear and tear or normal deterioration, you’re probably uninsured. 

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’ 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, you may be able to claim for damage from the Coal Authority.

If in doubt, take a look at 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 in the future.

How can I prevent cracks in my walls?

It can be difficult to prevent cracks forming in the walls of your home, because the cause of the crack is rarely visible before the damage is done.

One thing you can control is checking for any drainage issues and leaky pipes. Water damage is a cause of severe cracks forming, so preventing this is a good step in protecting your home.

If you live in an area that’s prone to subsidence, you should avoid disrupting the land as much as possible. Don’t plant large trees and plants close to your home, as their roots can dry out the soil close to the foundations. On the other hand, removing a long-standing tree can cause a sudden buildup of moisture, which could cause other problems.

How can I fix cracked walls?

If it’s a superficial or minor crack, you should be able to fix it with a bit of DIY. Simply use some filler to cover the crack, wait for it to dry, sand it and then paint.

If it’s a more severe crack and you’re worried about potential structural damage, you should consult a professional structural engineer immediately.

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Frequently asked questions

What are the different types of ground movement?

One of the first things insurance providers will look at when you make a claim is the probable cause of the damage, as this could make a difference as to whether a claim is paid or not. 

There are four main causes of ground movement, 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 repairing cracks in my outbuildings?

It depends on your insurance policy. 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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Anna McEntee - Insurance comparison expert

Anna’s all about delivering fantastic insurance products at a great price. Value is the most important thing for Anna, as she cuts through the jargon and finds what’s most important and worth your hard-earned money.

Learn more about Anna

Andy Webb - Insurance expert

Andy Webb is an award-winning personal finance journalist and broadcaster. Combined, his Be Clever With Your Cash blog, Andy Clever Cash YouTube channel and Cash Chats podcast have been read, watched and listened to by millions.

Learn more about Andy

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