What is subsidence?
Subsidence occurs when the foundation of your house collapses or sinks.
This is often caused by:
- Soil, usually clay, shrinking and swelling because of the weather.
- Nearby trees and shrubs absorbing the moisture in the soil beneath your home.
- Leaking drains softening the ground under your home.
What are the signs of subsidence?
Your property might be suffering from subsidence if you spot any of the following signs:
- Sudden cracks in plaster and brickwork that are wider at the top than at the bottom
- Doors and widows sticking for no reason
- Rippling wallpaper that isn’t caused by damp
It’s important to note that cracks can appear on walls for varying reasons, so spotting one might not be a cause for panic. 'Settlement' - where a building settles under its own weight - can also cause cracks to appear on walls. This is often seen in newly built homes and extensions.
If a crack is caused by subsidence it will be:
- More than 3mm thick - often getting wider over time
- Wider at the top than at the bottom
- Visible from inside and outside of your home
- Close to doors and windows
Is subsidence covered by home insurance?
Terms and conditions relating to subsidence vary between home insurance providers.
Most home insurers will cover damage caused by subsidence, but the excess is often larger - normally £1,000.
Buildings insurance policies usually only cover subsidence damage to the house itself. Areas such as patios, garden walls, driveways and swimming pools aren’t usually covered unless your house is damaged at the same time.
If you have made a claim for subsidence in the past year and are now looking to switch provider, many new insurers are likely to decline you.
The Royal Institution of Chartered Surveyors can provide further practical advice and can recommend a specialist if you suspect your property has subsidence.
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Is my home at risk of subsidence?
Factors that can affect your risk of subsidence include:
Properties built on clay soil are at great risk of experiencing subsidence. Clay soil can shrink, crack and shift during hot, dry weather, making the ground unstable and potentially causing the foundations of your property to sink.
Homes in drought prone areas are particularly at risk of subsidence because the soil is much more likely to dry out.
Trees and shrubs
Trees and shrubs around your home can increase your risk of subsidence. Some species absorb a lot more water which makes the soil much drier.
Subsidence is more common in Victorian and Edwardian houses as their foundations are shallower than the current UK minimum of 1m. This makes them more susceptible to damage from any movements in the ground.
Leaking drains and water mains can increase your risk of subsidence as they wash away or soften soil, causing it compact under the weight of your property over time.
Properties that have had their foundations underpinned may have experienced subsidence previously and are therefore at a greater risk.
Can I reduce my risk of subsidence?
You can reduce your risk of subsidence by taking the following steps:
- Make sure you plant trees and shrubs at least 5-10 metres away from your property
- Prune the branches on your trees regularly
- Keep pipes and drainage systems well maintained to stop water leaking into the soil beneath your house
- Check the surveyor’s report for signs of subsidence before buying a new home