What is subsidence?
Subsidence is the shrinking or moving of the earth that your home is built on. As a result, the foundations move and cracks appear in the brickwork.
What causes subsidence?
- There are a few causes, but the most common is tree roots – which cause movement when they grow under the foundations.
Even in the less invasive cases, the roots extract moisture from the soil, making the ground contract.
Pruning back or removing the tree can solve the problem, but this alone is not always enough.
- Clay soil can also cause subsidence. It tends to hold a lot of water, but if the water table drops during dry weather, it will shrink.
Hidden mine shafts or bell mines, defective drains, culverts and pipework and sandy/ gravelly soil can also cause subsidence.
Leaking water can wash away unstable soil from around a building’s foundations.
How can you spot subsidence?
Not all cracks in the plaster or bricks mean subsidence.
New or expanding cracks wider than 3mm may be due to subsidence – especially following dry weather.
Cracks wider at the top than the bottom and that run diagonally, can also indicate subsidence – as well as a crack visible both inside and outside.
Subsidence can cause homeowners a great deal of hassle – especially if they’re lacking adequate cover.
Homeowners should check with their brokers or their policy documents, that they have adequate buildings insurance protection – covering them for subsidence.
Each time you enquire about Buildings insurance – ensure that subsidence cover is included, since you won’t be covered if you don’t notify your insurer and most mortgage agreements stipulate that you must have buildings insurance.
You normally have to pay the first £1,000 excess of your policy – but it can be more.
Most damage should be covered – including alternative accommodation, dependent on your policy.
Generally, across insurance policies, making a claim can increase your premium when you come to renew and you may lose some no claims bonus or find some insurers won’t quote for a previously affected property.
If you’re looking to buy a house that has suffered from subsidence…
- Ensure you have a full structural survey carried out before buying the property
- Find out when, why and how it was fixed.
- Take advice from your broker – who can help you to arrange cover.
Normally, your current insurer will continue to cover you after subsidence – look for an insurer who will transfer the insurance to a new buyer – as it’s easier to sell the property if insurance is available.
If you suspect your property has subsidence…
- Contact your insurance broker – to inform them/ seek advice
- Deal with it right away – this doesn’t go away on its own
- Monitor the subsidence going forward
- In the worst cases, you’ll need the help of a structural engineer.
The earlier you discover/ start to deal with subsidence, the easier it is to address it. Some simple solutions can help…
- Fix a defective drain or water pipe
- Sometimes, metal piles can be used to shore up the foundations – if the foundations are strong enough
- Jet grouting can also help. This involves filling underground gaps and making unstable soil solid.
- Sometimes, underpinning is required. This is when pits are dug under the foundations and filled with concrete – which is an expensive process but will ensure the sturdiness of your house.