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Subsidence

What is it?

Subsidence is when the ground beneath a building sinks, pulling the property’s foundations down with it. Subsistence usually occurs when the ground loses moisture and shrinks due to prolonged dry spells, or the presence of trees and shrubs which cause the soil to lose moisture. 
 

Subsidence can be caused by a variety of factors including: 

  • 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, and so can dry the soil out. 
  • Local mining activity – Old mines and former quarry or pit sites can cause instability if the fill-in material collapses. 
  • Leaking drains and water mains can wash away or soften soil. Sandy, gravely soils are the most vulnerable to washing away. 

Other reasons why a properties foundation can move include: 

  • Heave – When the ground beneath a building moves upwards. 
  • Landslip/Landslide – When the ground beneath a building moves down a slope, taking the property with it. 

How to spot it?

The first sign of subsidence is usually the appearance of cracks in your home’s walls, either in the internal plasterwork or external brickwork. Subsidence cracks are quite distinctive from other cracks. They usually appear suddenly, especially after long periods of dry weather, and tend to be: 

  • Diagonal, and wider at the top than at the bottom 
  • Thicker than a 10 pence coin 
  • Found around doors and windows 

Other signs of subsidence include doors and windows sticking for no obvious reason, and wallpaper ripping or crinkling that is not caused by damp.  

However, if a crack appears it does not necessarily mean subsidence. Many properties experience cracking from time to time, but only rarely is this caused by subsidence. Most common causes for cracks could include:  

  • That 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 build 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. 

How to prevent it? 

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

What to do if it happens? 

If you suspect your property has suffered from subsidence damage, contact your insurer as soon as possible. They will advise you on the next steps to be taken. Where appropriate your insurer may send a specialist/engineer to your home to examine the damage caused by subsidence and determine its cause.  

If the damage is minor, the cause can be easily determined and the movement of your home has stopped, repairs will usually be carried out straight away. 

If the damage is severe and subsidence is ongoing, the movement of your home many be monitored over a period of time so engineers can figure out a long-term solution.  

In extreme cases your property may need to be underpinned – where a building’s foundations are strengthened or deepened – to prevent further subsidence.  

Your buildings insurance policy will usually cover you for damage caused to the structure of your property and outbuildings by subsidence. 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).  

Damage to surrounding structures such as garden walls, fences, gates, patios and driveways is not usually covered, unless the damage occurs at the same time as the damage to your home. 

If the damage to your home is so severe that the property is uninhabitable, your insurance will cover the cost of alternative accommodation while repairs are being carried out.  

The ABI recommends contacting your buildings insurance provide to find out exactly what is covered under your policy and how much excess you will need to pay. 

Claiming for subsidence caused by coal mining 

Claims for damage caused by coal mining are dealt with through the Coal Authority, not through your usual home insurance provider. 

If your property has suffered from subsidence due to coal mining: 

  • Download and fill out the Coal Authority's Damage Notice Form 
  • Send your completed Damage Notice Form to the owner of the coal mine in your area 
  • The coal mine owner will usually send an engineer to inspect the damage to your home 
  • Tell your home insurance provider that you have made a claim for subsidence through the Coal Authority 

Getting insurance after making a subsidence claim 

Homeowners often find it difficult or expensive to get property insurance after making a subsidence claim.  

  • Getting cover from your current insurance provider 
    • Under ABI guidance, ABI member companies are committed to working with policyholders to manage ongoing subsidence risk and maintain cover, however there may be circumstances where continuation of cover is not possible.  
  • Getting cover from a new insurance provider 
    • If your property is still at risk of subsidence you may have to pay a higher premium than other homeowners and your policy may be subject to different terms and conditions. 
    • If your home has suffered from subsidence damage in the past and you want to change your insurance provider, contact an insurance broker through the British Insurance Brokers' Association (BIBA) for specialist advice. 
  • If you discover subsidence damage after changing your insurance provider 
    • If you change insurer and then discover subsidence damage, the ABI's subsidence claim handling agreement will help determine whether your previous or current insurer should handle your claim. The decision will be based on the amount of time that has passed between you switching insurer, discovering subsidence damage, and notifying your insurer: 
      • if the date of notification is within eight weeks of changing insurance provider your previous insurer will handle your claim 
      • if the date of notification is between eight weeks and one year of switching provider then your previous and current insurers will share the cost of your claim 
      • if the date of notification is more than a year after you switched insurers your current insurance provider will deal with your claim 

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