SAM Conveyancing explains When to Worry About Cracks in Brick
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When to Worry About Cracks in Brick?

27/01/2023
(Last Updated: 23/08/2023)
5,151
7 min read
Key Takeaways

When should I be worried about cracks in brick?

Cracks in the brickwork of a building can be a sign that the ground is shifting - this is called subsidence. If the ground under the foundation shifts unevenly, then the house can't settle normally. For example, one side of the house might sink slightly further or faster than the rest of the house, causing cracks in the bricks. While many of the cracks which may appear in a building are not disastrous, subsidence must be addressed as soon as possible to avoid compromising the building's structural integrity.

Read more to learn about different types of cracks in the walls of your house and when to worry about cracks in brick being structural.

Are cracks in brickwork serious?

Some cracks in brickwork are more serious than others. The less serious ones, like the ones caused by spalled bricks should still be treated and filled, as any breach in the external skin of the building can allow water in, causing damp or mould. If water sits inside the cracks and freezes it will expand and may force the cracks to widen.

More serious cracks will require a structural assessment, to check if there are issues with the foundation or the structural integrity of the building. You may find that tree roots are slowly damaging the foundation, or construction materials were defective, such as poorly mixed mortar destabilising brick, stone or blockwork.

Severe cracks will require the services of a structural engineer. If the foundation is shifting due to subsidence, then the property may be dangerous. Underpinning and or bracing may be required to protect your safety and your investment.

How do you tell if a crack in a wall is serious?


  • Cracks narrower than 2mm are usually not serious

  • All buildings will settle after they are built. Extreme weather, including frost and high wind, can also create minor flexing and cracking in the structure. You should, however, fill them in to stop water permeating the building and causing damp, or freezing and expanding, making cracks worse. Keep an eye on them and watch for widening or for more cracks appearing around the same stress area of the brickwork. If they do, you should call a professional.

  • Brick veneer cracks are usually superficial

  • Brick veneer is not structural and is much thinner than structural brick, it is more likely to show cracks faster. However, it may be a sign that the structure beneath is under stress. If you are unsure, it's best to call a professional.

  • External vertical cracks aren't usually serious, but internal vertical cracks are

  • Hot weather will cause the bricks to expand, which may result in vertical cracks in the mortar. This is usually not serious, unless the crack gets wider than 2mm. If you get long vertical cracks appearing internally, you should consult a professional.

  • External horizontal cracks are serious

  • Horizontal cracks are more likely to be an indication of ground movement, especially where you see more than one horizontal crack running in parallel.

  • Stepped cracks are often serious

  • Cracks which step up the brickwork diagonally are often a sign of subsidence under your foundation. If the crack gets bigger than 2mm or you notice other signs of subsidence, such as doors or windows sticking, you should get a professional in to take a look.

  • Cracks from 2-25mm are fairly serious

  • If you can fit the width of a 50 pence piece into the gap, you may have a problem. You should have a structural engineer assess the property for structural damage.

  • Cracks over 25mm are extremely serious

  • You need a structural engineer to visit the property and you may need a subsidence survey.

How can you tell if a crack is structural?

Now you know what types of cracks are and aren't a cause for concern, you know what to look out for. But unless the house is visibly falling down, most of the time you won't be able to tell if the crack is structural, yourself.

Depending on the severity of the cracks, you may need a surveyor or a structural engineer to assess the damage. Fill in the quote form below, or call or contact us today and our team will talk you through your options.

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Caragh Bailey, Digital Marketing
Written by:
Caragh is an excellent writer in her own right as well as an accomplished copy editor for both fiction and non-fiction books, news articles and editorials. She has written extensively for SAM for a variety of conveyancing, survey and mortgage related articles.
Andrew Boast of Sam Conveyancing
Reviewed by:
Andrew started his career in 2000 working within conveyancing solicitor firms and grew hands on knowledge of a wide variety of conveyancing challenges and solutions. After helping in excess of 50,000 clients in his career, he uses all this experience within his article writing for SAM, mainstream media and his self published book How to Buy a House Without Killing Anyone.

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