What is subsidence?

November 23, 2020 10:33 am Published by

Subsidence occurs when the ground beneath a property begins to sink and shift downwards, pulling the building’s foundations down with it. As subsidence occurs, the foundations become misaligned and the property begins to sink into the ground unevenly.

The word “subsidence” is enough to give any property owner a sinking feeling. It can be caused by both human activity and naturally occurring processes, requiring immediate attention and action once identified.

Picture of a house with subsidence1
  © Copyright Stephen McKay and licensed for reuse under this Creative Commons Licence

What causes subsidence?

  • Clay soil shrinking and cracking in dry weather
  • Disused mines or other excavations under property
  • Vibrations through the ground from things such as nearby train lines
  • Trees causing soil shrinkage when their roots extract water from surrounding ground. This is more common with trees such as willow, oak and poplar as they have very high water demands.
  • Large volumes of escaped water from leaking or damaged pipes. This can wash away fine particles in soil or cause it to become soft, reducing its strength and ability to support the property

Signs of subsidence

Cracks in brickwork are usually the most obvious sign of subsidence. If you have identified cracks which are causing concern, don’t jump to any conclusions just yet. Minor cracks occur as properties shrink and swell as a result of changes in temperature. They might also appear in new build house or one that has recently been painted – this is known as settling and isn’t usually a large cause for concern. There are some characteristics specific to cases of subsidence that you can identify yourself.

If a crack has arisen as a result of subsidence, it will be diagonal. These cracks are visible from both within and outside of a property, are wider at the top and are usually thicker than 3mm – you should be able to fit a 10p coin or credit card in there. They are often found near doors and windows or where an extension has been added to a property. If existing cracks are expanding or have appeared after a long spell of dry weather, consult a surveyor.

If you notice that any doors or windows are becoming stuck, this might suggest that the surrounding frames have changed shape – this is another tell-tale sign of subsidence.

Similarly, if you begin to notice rippling in your wallpaper that is not caused by damp, you should contact a surveyor. They will assess the suspected subsidence and advise on the action that should be taken.

Once the causes are addressed and identified, you can begin working on the necessary repairs.

Subsidence cracks

How to fix subsidence

The sooner the subsidence is fixed, the less damage will be done to the property. You will need to take immediate steps to hold the damage. Consult with a surveyor as soon as possible.

Fixing subsidence can be a length process as it usually requires measuring and monitoring things such as cracks for long periods of time. This could potentially take up to, and sometimes even longer than a year.

Underpinning is one well-known fix for subsidence. It entails digging beneath existing foundations and adding support to strengthen them, preventing any further movement.

If necessary, you should repair any damaged drains or pipes which are contributing to or causing the issue.

If nearby trees are causing the subsidence, you will need to prune or remove their roots. If trees are the root of the issue, be wary of rushing to remove them as this can cause further issues such as instability and water logging. Be sure to consult with a surveyor and a tree surgeon to determine the appropriate course of action.

Preventing subsidence

Preventative maintenance is vital for homeowners whose properties are at risk of subsidence.

Research has shown that most cases of subsidence involve trees to some degree. For this reason, you should ensure that large trees and shrubs are planted at a safe distance from your house. If there is a large tree near your property, it is worth having it professionally surveyed every few years in order to assess its overall health and determine whether pruning or felling will be necessary. These reports should be stored in a safe space in case they are requested by insurance companies or public bodies. 

Drains should be kept clear at all times, be sure to regularly check your guttering. Maintaining external pipework is also important, so keep an eye on your property’s outer plumbing as well as inner.

Catching and collecting rainwater in barrels can help to prevent subsidence. This water can later be used to water your garden.

Typical safe distance of tree to building2

What does subsidence mean for your buildings insurance?

Not all buildings insurance policies will cover subsidence, so it’s crucial for homeowners to read the small print.

Although most buildings insurance policies will cover the cost of repairing damage or loss as a result of subsidence, many will not cover measures taken to prevent further movement of the property. For example, a policy may cover the cost of repairing cracks in your property, but not of preventing any further movement.

Some common exclusions relating to subsidence claims include:

  • damage to external items such as paths, gates, swimming pools, septic tanks, drives and hedges unless the main structure of the home is also affected at the same time by the same event;
  • normal bedding down and settlement of new structures;
  • damage caused by faulty design, workmanship or material;
  • damage caused by coastal, river or watercourse erosion;
  • damage caused while the building is undergoing ay structural repairs, extensions or alterations;
  • damage which originated prior to the inception of cover.

It can also be difficult to source home insurance for a previously underpinned house, so be sure to retain any structural engineers reports and/or certificates of structural adequacy as any potential new insurer will require the see these to offer cover.

If you are considering buying a property that has been treated for subsidence, the owner should have a completion certificate and a certificate of structural adequacy.

When arranging buildings insurance, it is crucial to be sure that you are getting the policy best suited to your requirements at the most competitive price. Consider approaching a broker with excellent market relationships, their connection with insurers can help reduce the cost of your premium.

Brunel is an independent, specialist broker with a wealth of experience in the property insurance industry. We approach the entire open market, then use our excellent market relationships to whittle down the cost of your premium, arranging the most suitable cover at a competitive price. For a free, no-obligation quotation, call our quote line on 0345 873 4451 or get in touch via contactus@brunel-insurance.co.uk.


https://www.geograph.org.uk/photo/6365082 1

https://www.abi.org.uk/globalassets/sitecore/files/documents/publications/public/migrated/home/protecting-your-home-from-subsidence-damage.pdf 2

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This post was written by Sadie Tincknell