Subsidence: what is it and how to prevent it?

Subsidence is a form of ground movement that can cause quite serious and costly damage to properties. It will not only potentially impact your property’s structural safety but also its resale value.

Around 5% of claims reported to the Hamilton Fraser Total Landlord Insurance claims team in the last 3 years have been as a result of subsidence, with the highest ever claim costing an enormous £112,255.

Although subsidence only affects the minority of properties, as a landlord, it is important that you’re prepared by taking any preventative measures and knowing what to look out for.

What is subsidence?

Subsidence is caused when the earth beneath a building moves downwards, resulting in instability and less support underneath part or all of the foundations of a property, causing it to sink.

What causes subsidence?

There are a number of factors that can contribute to subsidence cracks not all properties are at equal risk. Causes of subsidence can include:

  • Shrinkage of clay soils in warm weather – clay soils are more commonly found in the South and East of Britain. Clay soil can shrink and move during hot and dry weather,
    especially with the lack of rainfall over recent years, making the ground unstable.
  • Trees growing close to the property – vegetation near the building can cause movement by growing under foundations and can draw water from the soil through their root systems. Some species of trees and shrubs can draw a lot more water which can dry the soil out further. For example, a mature oak tree can draw up to 1,000 litres per day.
  • Leaking drains – defective drains can cause erosion or washing away of soil. They can also soften the ground which could cause the soil to compact under the weight of your rental property.
  • Soil erosion – soil can naturally decompose due to oxidisation and can lead to a reduction in its volume.

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Subsidence warning signs: what should you look out for?

The most obvious sign of subsidence are cracks. The majority of cracks result from settlement, when a building moves under its own weight in its first few years which is mostly nothing to be concerned about.

However, you need to look for diagonal cracks that increase in width the further away they are from ground level. Cracking associated with subsidence is usually visible both internally and externally and is normally at least 3mm wide and can be as thick as a 10p coin.

The cracks will appear in brickwork and plasterwork around doors and windows or between different parts of the property such as near an extension.

Other warning signs of subsidence can include wrinkled wallpaper at the wall and ceiling joins and doors and windows sticking as the frames become misshapen.

5 tips to prevent subsidence

To cut down the risks of subsidence you can;

1. Avoid planting trees or shrubs too close your property or outbuildings. We recommend that any new trees or shrubs are planted a minimum of the same distance away from your property as their expected mature height (be aware of neighbouring properties too).

2. If a mature tree is already positioned too close to your property, seek advice from a surveyor or tree expert about how best to manage it and whether it should be removed.

3. Regularly prune trees and shrubs to help reduce how much water is absorbed.

4. Carry out regular maintenance of drains and pipes. You should check for blocked or leaking drains, clear the gutters of leaves and dirt regularly and check pipes to ensure there are no damaging splits.

5. Look for signs of subsidence when carrying out regular inspections of your rental property.

Knowing what warning signs to look out for and having the right landlord insurance coverage will help you identify and fix subsidence in time. In the event that you discover subsidence at your rental property call our claims team on 0345 310 6370 as soon as possible to report the claim.