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How subsidence can affect your home – what you need to know

Subsidence can be a worrying problem affecting your property, potentially endangering the structural safety of your home and its market value. Your home insurance can normally help deal with the problem for you. This Q. and A. explains what causes it, what to look out for, cover under home insurance, and what to do if you suspect the worst.

  • What is subsidence?

    Subsidence is when the ground beneath a building sinks, pulling the property’s foundations down with it. It usually occurs when the ground loses moisture and shrinks. Reasons for this include:

    -  Prolonged dry spells which cause soil to lose water,
    -  Trees and shrubs which can absorb significant volumes of water from the soil.

    Less common are heave and landslip: 

    -  Heave is an upward movement of the ground supporting the building;
    -  Landslip is the movement of ground down an incline or slope trying to find a natural level.

  • What can cause subsidence?

    Subsidence can be caused by factors such as:

    - Soil type. Clay soils in particular are vulnerable because they shrink, crack and shift during hot, dry weather depending on their water content.
    - Trees and shrubs. Where clay soils are present, vegetation can be an issue if they are close to your foundations as some species absorb a lot more water, so dry the soil out.
    - Local mining activity. Old mines, and former quarry or pit sites can cause instability if the fill-in material collapses. To find out if you could be in an affected area for old coal mining, check here
    - Leaking drains and water mains can wash away or soften soil.  Sandy, gravely soils are the most vulnerable to washing away.

  • What are the tell-tale signs of subsidence?

    The following may mean that the property is being affected by subsidence:-

    - Cracks. Not every crack means a problem (see below), but there may be an issue if it is more than 3millimetres wide (the depth of a 10p coin), diagonal and wider at the top than the bottom, and visible from the inside and outside.
    - Doors and windows sticking for no obvious reason.
    - Wallpaper ripping or crinkling that is not caused by damp.

  • If a crack appears does this mean subsidence?

    Not necessarily. Many properties experience cracking from time to time, but only rarely is this caused by subsidence. More common causes for cracks include:

    - Buildings naturally shrink and swell in response to changes in temperature and humidity, leading to minor cracks where walls and ceilings meet
    - New homes and recently built extensions often experience cracking as the structures settle under their own weight
    - Fine cracks are also common in freshly plastered walls as they dry out

    Cracks arising from these causes are usually uniform in width, narrow (hairline to 3mm) and can be dealt with during routine maintenance or redecoration.

  • Will my home insurance cover subsidence?

    Yes, your main home and outbuildings are covered for damage due to subsidence, heave and landslip under a standard home insurance policy.  Most policies will have an excess of around £1,000 for a subsidence claim (an excess is the first part of each claim that you will be responsible for covering). However, if you have had subsidence previously, then the excess could be higher (see below).

  • What sort of damage isn’t covered?

    If movement occurs to driveways/patios or garden walls without also damaging the house or it’s outbuildings, this generally is excluded from most Home policies. You should check with your insurer for details of your individual cover.

    If the structure hasn’t been built in line with good building practice and this is the cause of the damage, this is often also not covered.

  • What should I do if I suspect subsidence?

    Contact your insurer as soon as possible. They will advise you on the next steps to be taken. Where appropriate, specialists will be appointed to investigate the cause of the damage and to arrange for repair work to be carried out. The subsidence damage can often be rectified by stopping the cause of the subsidence, removing trees affecting the property, or in exceptional circumstances, by underpinning (strengthening existing foundations) to tolerate the subsidence if it cannot be stopped. Where the damage is less severe, the cracks can often be repaired with a resin-based filler and strengthening the surrounding masonry.

  • If I have claimed for subsidence damage will I still be able to get affordable buildings insurance in the future?

    Subsidence claims can be very expensive, so certainly could affect the cost of future property insurance, and the level of any policy excess. An insurer will need to assess the risk, but ABI member companies are committed to working with policyholders to manage any subsidence risk and maintain cover. 

    Where a claim arises, the insurer handling the claim will, in the majority of cases, continue to provide subsidence cover on the property after the repair is completed, as long the repair has been carried out under their direction, or with their approval.

    However, there may be circumstances where continuation of cover is not possible in which case you should shop around to find alternative cover and consider using a specialist broker (see Useful addresses).

  • What about if I am selling my property. Will the new owners be able to access insurance?

    Talk to your insurer as they can normally agree to continue to insure the property for the purchaser.

  • What steps can I take to reduce the risk?

    While not all subsidence problems can be avoided, a few simple actions can be taken to protect your property and prevent long-term problems if you live in a clay soil area:

    - Trees or large shrubs close to the house, garage or outbuildings can cause soils to dry out significantly, so these may need to be managed.  We would recommend that you seek professional advice from a tree specialist before undertaking any work (see Useful addresses).

    - Ensure that gutters, pipes and plumbing are well maintained to avoid leaks.

Useful addresses:

For advice on finding an insurance broker visit: www.biba.org.uk

For information on finding a structural surveyor: The Royal Institute for Structural Surveyors

For advice on tree planting distances: The Arboricultural Association