Subsidence Explained

Subsidence is the process of the ground underneath a property collapsing or shrinking and impacting its foundations. The opposite is called heave where the ground underneath expands pushing the foundations up. Either way the result is part of the property moving causing cracks to appear in the walls. This is not the same as settlement which is where the weight of the building compresses the ground underneath.

Indicators of subsidence
There are several things that can indicate subsidence:

A change in the fit of doors or windows. If they start to stick and you find it difficult to open and close any you should investigate further.
Prominent cracks appearing in walls and ceilings.This is particularly true of cracks on the inside and outside walls. Any that are diagonal or stepped in in nature are the most concerning.
Wallpaper coverings bubbling or rippling with no indication of damp.
But that’s not to say that all cracks are caused by subsidence. Cracks and lines can and will appear on walls for other reasons, so if you spot one, don’t panic! Thermal expansion and contraction of the different materials used to build a house is just one. If you think your property is suffering from subsidence you should contact your insurer though.

What causes subsidence to happen?
The two most common causes of subsidence are:

Clay soil shrinkage. As water is removed from clay it literally shrinks. If a house is built over clay and one area get drier than another it will create stress on the foundations.
Defective drains. A leaking drain can wash away soil underneath a property or make it so wet it is less able to support the weight of the building.
What could reduce the risk of it happening?
Keeping vegetation around a property under control. Use the rule of thumb that if the height of any vegetation is more that the distance to the property it can impact the foundations.

Regularly inspecting drains and attending to any issues promptly.

Are there any reasons why a property could be more at risk?
If it’s built on clay soil as described before this is much more at risk of subsidence.

Houses in drought prone areas that are also built on clay add to the risk as the soil is much subsidence signs more likely to dry out.

Older properties tend to be less well built and with smaller foundations than now. The term “Jerry built” originates from the 19th Century and for good reason.

Your home insurance usually covers subsidence.
The buildings insurance part of your home insurance policy usually covers subsidence damage to the house itself. However, most providers do not cover parts of your property outside your home, like garages, driveways, sheds, outhouses etc if the damage does not also affect the main house. Check your policy carefully.

If you have had subsidence in the past on your property you may find it hard to get insured with mainstream insurers and you will require a specialist insurance provider. Frontier can offer subsidence cover as standard for properties certified as having no ongoing structural movement. Even if the property has previously subsided or has been underpinned. Providing you able are to provide a Certificate of Structural Adequacy following the repair, it’s covered.

The BIBA (British Insurance Brokers' Association) can provide you with practical advice on subsidence and can also recommend a specialist if you suspect your property has subsidence.

What happens if I need to claim for subsidence damage?
Making a claim for subsidence can be complicated. The property will have to be assessed by a specialist to advise on the condition of the property and likely cause of any damage. There will invariably be a period of monitoring to determine if any movement is historical or ongoing. This alone can take many months. Once the cause is clear a plan to fix the property can be determined. This could range from a simple decorating job to extensive underpinning and invasive structural repairs.

And finally, any history of subsidence will have to be disclosed to any future purchaser of a property. This may make it harder to sell or affect the market value.

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