It’s a common sight for homeowners: a small crack forming between the original structure of their house and a newer extension. While this might seem alarming at first, it’s important to understand that this isn’t always a major cause for concern. However, it’s still something that requires attention to ensure it doesn’t lead to more serious issues down the line. In this blog post, we’ll explore why these cracks appear, when you should worry, and how they can be fixed.
Why Do Cracks Appear?
When an extension is added to a house, two separate structures are effectively joined together. While builders aim to make the connection as seamless as possible, the materials used for the original house and the extension can settle and shift differently over time. Here are some common reasons for cracks forming where an extension meets the house:
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Natural Settlement: All buildings settle slightly over time as the ground beneath them shifts or compresses. This is especially common with new extensions that have been added to an older property. As the extension settles into place, a crack may appear at the junction between the old and new structures.
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Temperature and Moisture Changes: Different materials expand and contract in response to changes in temperature and moisture levels. This can put stress on the junction between the house and extension, causing cracks to form over time.
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Foundation Movement: If the foundations of the original house or the extension have moved slightly, this can lead to a crack at the join. This is more common if the soil beneath the foundations is prone to subsidence or shrinkage due to weather changes.
When Should You Be Concerned?
While small cracks are a normal part of any building’s life, there are times when you should take action. Here are a few signs that the crack between your house and extension could indicate a more serious issue:
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Widening Cracks: If the crack is getting wider over time or if it exceeds 5mm in width, it could be a sign of structural movement that needs to be addressed.
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Multiple Cracks: If you’re seeing several cracks in different areas where the extension meets the house, it may be worth having a professional take a look to rule out any foundation issues.
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Damp or Water Ingress: If water is getting into the crack, it could lead to damp problems inside your home. In this case, the crack will need to be repaired to prevent further damage.
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Movement in Doors or Windows: If the crack is accompanied by doors or windows sticking or becoming difficult to open, this could indicate more significant structural movement.
How Can These Cracks Be Fixed?
The good news is that most cracks where an extension meets the house can be fixed relatively easily, especially if they’re caught early. Here are a few common solutions:
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Flexible Filler or Sealant: In cases where the crack is caused by minor movement or expansion and contraction, a flexible filler or sealant can be used to fill the gap. This will allow the materials to continue moving slightly without the crack reappearing.
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Repointing or Re-Plastering: If the crack is more than just a surface issue, repointing or re-plastering may be necessary to fix it. This involves removing the old mortar or plaster and replacing it with new materials to strengthen the junction between the old and new structures.
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Structural Repairs: If the crack is a result of more serious foundation movement or subsidence, a structural repair may be needed. This could involve underpinning the foundations or installing structural supports to stabilise the extension and prevent further movement.
Preventing Cracks in the Future
While some cracks are inevitable, there are a few steps you can take to minimise the risk of them appearing where your extension meets the house:
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Regular Maintenance: Keep an eye on any existing cracks and make sure they don’t get worse over time. Regular maintenance, such as repointing or re-sealing, can prevent minor cracks from becoming bigger problems.
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Foundation Inspection: If you’re planning to build an extension, make sure the foundations are properly designed to handle the load of the new structure. A professional surveyor can assess the ground conditions and recommend the best type of foundation for your extension.
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Allow for Movement: When adding an extension, it’s important to allow for some movement between the new and old structures. This can be done by using flexible materials or expansion joints, which will absorb any movement without causing cracks.
Conclusion
Cracks where an extension meets the house are a common issue for many homeowners, but they don’t always indicate a serious problem. In most cases, they are the result of natural settlement or minor movement between the two structures. However, it’s important to monitor the crack and take action if it starts to widen or cause other issues. By addressing the crack early and ensuring your extension is properly maintained, you can prevent more serious problems down the line and keep your home in great condition.