Cracks in walls and ceilings: When to worry

Cracks in walls and ceilings: When to worry

Finding cracks in your walls or on your ceiling might seem like a bad sign. But there’s all sorts of reasons why cracks can form in walls and ceilings, so it’s important not to worry until you know exactly why they’re there.

In this blog we’ve outlined everything you need to know about cracks in your walls and ceilings, and what you can do about them.


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What causes cracks in walls and ceilings?

There are all sorts of things that can cause cracks in walls and ceilings. Most cracks happen because of of normal processes as your house ages, but others can indicate more serious issues like subsidence. Small cracks might be caused by:

  • New plaster that was applied too thinly can show hairline cracks after drying
  • Newly built homes settle into their foundations and can show small cracks in walls
  • Temperature changes can cause cracks in walls as the brickwork expands and contracts over the years
  • Road traffic vibration can cause small cracks in houses next to busy roads
  • If you’ve recently replaced wooden window frames with uPVC frames, cracks can form if the window isn’t supported properly

Larger cracks in your walls and ceilings can also happen for a range of reasons. The larger the crack, the more of a cause for concern, as it can show signs of structural damage or subsidence. Structural damage might be caused by:

  • Heavy rainfall or flooding
  • Long periods of dry weather
  • Poor drainage and leaks under your house
  • Roots from nearby trees drying out the soil around foundations
  • Poorly built foundations
  • Local mining activity
  • Poorly supported doors and windows

If you’re worried about subsidence, you can check out our blog ‘What is subsidence?



When should I worry about cracks in my walls and ceilings?

Most hairline cracks in plaster and brickwork tend to be just a sign that your house is ageing, and shouldn’t be much to worry about. Though there are times when it’s best to be cautious about cracks in your walls and ceiling. These are the things to look out for:

  • How wide are the cracks? - The first thing you can look at is how wide the crack in your wall or ceiling is. Anything from 1 to 5 mm is not usually a cause for concern, and any small cracks in plaster can be easily repaired. Any cracks from 5 to 15 mm could show signs of structural damage, depending on their position. Cracks wider than 25 mm (an inch) could be a sign of serious structural damage, so it’s best to get a professional to come and take a look as soon as possible.
  • Do the cracks run diagonally? - Vertical cracks in plaster tend to just show signs of contraction whilst the plaster was drying. You can wait a little while in case any more cracks show up, and simply repair the cracks with more plaster. Similarly, vertical cracks in external walls are usually caused by the earth compacting under the weight of the house and tend not to be a cause for concern. Diagonal cracks in plaster or external walls can, however, show signs of structural movement. Wide, diagonal cracks should be looked at more carefully rather than just plastered over.
  • Where are the cracks? - Cracks around windows tend not to be too much of an issue, but cracks above doors can show signs of foundation damage or that the brickwork above the door is poorly supported. Cracks between the wall and the ceiling could also show signs of truss uplift (the roof coming off the walls). If you have a flat roof, cracks in the middle of the ceiling could also show signs of leaks caused by poor roof drainage.
  • Are the cracks discoloured? - Cracks in your ceiling or wall that are a different colour like brown or yellow are signs of damp or leaks. This can be serious, depending on the cause, so it’s best to find the source as soon as you can to avoid any lasting damage.
  • Is there daylight coming through the crack? - If you’re seeing daylight coming through a crack in an external wall, it could be a sign of quite serious subsidence. It’s best to get these looked at as soon as possible.
  • Is the wall or ceiling bowing? - A wall or ceiling with a large crack that is also bowing inwards could indicate some fairly serious structural movement. When ceilings and brickwork bow, they’re often on the way to falling down, so it’s important to be very careful in these situations.

If you think you might have a water leak, you can check out our blog ‘Claiming on house insurance for water leak


What to do when you find a crack in your wall or ceiling

If you’re worried about a crack in your wall or ceiling, it’s important to notify someone as soon as possible. If you’re renting, this is your landlord. For leaseholders, it’s best to talk to the freeholder as this will likely be their responsibility. In either case they probably have buildings insurance that will take care of anything more serious. For small cracks in plaster, it might be up to you to get them fixed, so you can check your lease or rental agreement to make sure.

If you’re wondering whose responsibility it might be to get buildings insurance, you can check out our blog ‘Who pays Buildings Insurance?

If you’re the freeholder, it’s best to talk to a professional builder, structural engineer, or surveyor as soon as possible. They’ll be able to tell you how serious your cracks might be, check if any movement is still ongoing, and help you plan any repair work that might need doing. Serious repairs can be quite costly, but they can help to stop your house falling down or becoming structurally unsound, so it’s worth the money.


A few final tips…

Finding cracks in your walls or ceilings isn’t necessarily anything to worry about. Small cracks in plaster or on an external wall are rarely a sign of major structural issues, but you might want to keep an eye on them if they get any bigger. Here are a last few things to remember about cracks in your walls and ceilings:

  • The main things to check if you find a crack on the wall is to look at its size, direction, and location. A big, diagonal, crack above a doorway could be a sign of structural movement.
  • Hairline cracks can be caused by lots of different things that aren’t anything to worry about. If you’ve just had some DIY work done and you’re seeing cracks in your plaster, wait a while for the cracks to settle before you do any repairs.
  • If you’re worried that a crack is a sign of more serious damage, it’s a good idea to get an expert to come and look at it as soon as possible.

Urban Jungle is not a financial advisor and information in this article should not be taken as advice or recommendation.