Rachel Elliot by

Posted on September 12, 2013

A few interesting facts:

  • On an annual basis, Subsidence affects as many properties in the UK as Floods.
  •  Subsidence is on the increase and over the last 10 yearshas cost the economy an estimated £3bn.
  • In research by Swiss Re, which is linked to climate change, it was reported that Subsidence in Europe will worsen and spread and could lead to an increase of more than 50% in the number of claims in the next 25 years.

Subsidence is defined as the downward movement of the site on which a building stands.  Most insurance policies will also cover the perils of Heave (upward movement of the ground under the site) and Landslip (downward movement of sloping ground).

Most people will be aware that the main cause of Subsidence is soil shrinkage – usually as a result of properties being built on clay soil.  In fact, this accounts for 75% of subsidence claims.  There is a clear geographic  pattern to the prevalence of clay soils which occur throughout England and Wales but rarely  in Scotland.  London clay, which underlies most of the GLA and Hampshire is particularly prone to subsidence.

One of the main influences of soil shrinkage is caused by trees.  Trees account for over 60% of all Subsidence claims.

Other causes of soil shrinkage include:

  • Leaking water mains and drains which can erode the soil or soften the ground.  These types of claims account for 15-20% of Subsidence claims.
  • Man made influence – i.e. removal of support around foundations/changes in the water table for example when sinking a well/ vibration caused by piling or constant heavy traffic.

Aside from soil shrinkage, Subsidence can also be caused by the ground falling away into a swallow hole as the result of chalk and limestone being eroded underground (commonly occurring in the Chilterns, Kent and Sussex).  Mining can also be a factor in certain parts of the country where the ground over old workings can give way.

We all know that any insurance claim dealing with Subsidence is likely to be a costly exercise.  That is why Subsidence cover has a higher policy excess than other perils (commonly  £1,000).

Subsidence claims are also very lengthy as insurers will generally monitor any movement for a period of time (usually a year so that the monitoring goes through all the seasons).  This allows the surveyors, on behalf of the insurers, to assess the best course of action for each particular property.  Remedies can include removing vegetation, repairing leaking drains, additional strengthening or, in more severe cases, underpinning the foundations of the property.