What is subsidence?

Subsidence insurance

If you think you may have a problem with subsidence, take action now. Read this guide to find out what causes subsidence and how your home insurance can help you get it sorted.

With a few home and garden maintenance tricks and the right type of home insurance, subsidence needn't leave you with a sinking feeling. 

What is subsidence?

Subsidence damage refers to the downward sinking movement of the ground beneath a property, often caused by unstable soil. Another type of ground movement is 'heave', which occurs when the ground beneath your property swells, meaning your property could begin to move. You'll find more details on subsidence and heave in your policy documents.

 

Do I need special  subsidence insurance?

Buildings insurance should cover your property for both house subsidence and heave.

But don't panic, relatively few houses actually subside. New homes are often prone to a period of 'settlement', this is different to subsidence. This is when the weight of the house settles into the foundations during the first few years and can sometimes cause the plasterwork to crack.

 

What causes subsidence?

The four main causes of subsidence are:

• Clay soil shrinking after long spells of dry weather.
• Trees and other vegetation taking moisture from the soil.
• Leaking drains, which wash away the subsoil below your foundations.
• Mining activity.

How will I know if my property is subsiding?

Cracks are the most obvious signs of house subsidence. Not every crack is a problem, but look out for distinctive diagonal cracks that appear at the edges of windows and doors. They are usually wider at the top than the bottom and can be quite noticeable.

The cracks can appear inside and out and run down past the damp proof course of your home to the foundations. You may find that they appear after there's been a long spell of dry weather.

Another thing to look out for is tearing wallpaper not caused by damp, and doors and windows that don’t close properly, stick for no reason, or close easily in winter but not summer.

What can you do to prevent subsidence?

Apart from moving to a different part of the country or doing a little rain dance, there's not much you can do to escape dry clay soil. But there are things you can do to manage the risk of subsidence and an underpinned house.

If there are trees and large shrubs, like wisteria, for example, planted close to your house, make sure you prune them regularly. For trees with a high water demand, their capacity to dry the soil can extend out as far as the tree is tall.

With large well-established trees, it's best to call in professional tree surgeons to manage their growth. This could prevent the tree from being cut down completely in the future.

Water pipes and guttering should be checked regularly to make sure they're not blocked or leaking. This is especially important for older properties where tree roots have been known to grow through clay pipes.

You could also improve the natural drainage around your home by replacing concrete or tarmac drives and patios with more porous materials, like gravel or grass.

Making a subsidence house insurance claim

If you think your property is subsiding, the first thing to do is contact your buildings insurance provider. The quicker you deal with the problem, the better. The first thing the insurer needs to do is check that the damage is due to subsidence. This is not always immediately obvious and can sometimes take several months to resolve. Would you like to know more about making a subsidence claim? Visit our home insurance claims page.

An expert may need to be sent to your property to assess the damage and decide the best course of action. This can involve a period of time where the property is monitored to see how much it moves and what's causing the movement.

Your insurer will normally pay for the cost of the expert they appoint to investigate the subsidence problem even if it turns out the damage is not due to subsidence.When the assessment is complete, the expert will recommend what needs to happen next. Only in extreme cases does the house need to be underpinned. This is where 'pins' of concrete are made underneath the existing foundations to support them.

Before any work begins, you'll need to pay any excess stated on your home insurance policy. There's usually a compulsory excess for subsidence work, which can often be more than the voluntary excess you agree when you take out your policy. If you have any difficulty in paying the excess speak to your insurer as they may be able to offset some of the repairs against the policy excess.
Once the work is agreed and the excess paid, the insurance company will cover the cost of the work and often the cost of moving to an alternative property if you need to move out whilst the work is happening.

After all, that's what buildings insurance is for.

How to treat subsidence

Once you've contacted your insurer, they'll probably want to send a surveyor round to take a look. The surveyor might take soil samples or investigate the building's foundations. After the initial inspection, they'll want to monitor the symptoms over a period of time – this will help them determine the extent of the problem.

Once subsidence has been diagnosed, there are a number of measures which can be taken, including:

• Tree management – sometimes a simple fix for subsidence if you have mature trees near your home.
• Repairing damaged pipes – often a straightforward correction if leaks cause soil to become waterlogged or washed away.
• Underpinning – a process where an additional base is added to help firm up the ground.
• Wall ties – can be used to tighten the inner or outer skin of the house.
• Reconstruction – may be necessary in rare cases where the existing structure can't be repaired.

Selling a house with subsidence damage

If you’re planning to sell your home and need to claim for subsidence damage, your insurer can often transfer the claim to the new owners. The repairs can then be carried out after the sale completes – you just need to agree who pays the excess as part of the sale. If the new owner wants buildings insurance, they can often obtain it through your existing insurer, so they should ask them for a quote.