4 COMMON CAUSES OF SUBSIDENCE

Written by

Emma Myrie

Insurance Underwriting Expert

Reviewed by

David Joyson

Home Insurance Expert & Customer Champion

Subsidence refers to the downward movement of the ground beneath a building’s foundations, causing varying degrees of damage, sometimes incurring massive cost and inconvenience to set right. This is why it is imperative to have a home insurance policy with subsidence insurance included.

There are 4 common causes of subsidence, though some are more likely to occur in particular areas than others. For instance, the most prevalent cause of subsidence is likely to be the shrinkage of clay soils, which are commonly found in the South and East of Britain.

1. CLAY SOIL

Clay soil in the UK has been created by the deposition of tiny rock particles along the beds of historic rivers, locking a certain amount of moisture within their matrix. Moisture will often stay locked inside clay for many decades (even after it has been removed from a wet environment, like a river) providing the clay is not exposed to excessive dehydration. When clay does dry out, it begins to shrink. When it is moistened again, the clay expands.

2. EXPANSION

Because this cycle is repeated every year, clay shrinkage and expansion usually goes unnoticed without causing any ill effects. It is during extended periods of drought that the cycle can be interrupted, and that is when things begin to go wrong. Often a long dry spell on its own will not be enough to cause clay soil to shrink to the point where subsidence is caused (though this is still a possibility) but when external influences, such as plant life and human activity, intervene then disaster can quickly strike.

3. TREE ROOTS

Tree roots can be a huge problem, as in a drought situation they are prone to branch out in search of moisture, and this can often be stored inside the matrix of clay soils. When the roots drain the clay dry, shrinkage takes place and disaster can ensue if the soil in question is beneath a building’s foundations. This problem can also occur as a result of human negligence, if building work reduces the amount of water an existing tree is able to draw from the ground (say, by laying concrete across its root system).

4. UNEVEN GROUNDS

To the West of the Tees-Exe line, where the geological make up is rockier, mine workings and instability of uneven ground are more likely causes of subsidence. Old mines that are no longer monitored can undergo settlement to the detriment of properties at surface level. This can often happen at great depth or far away from an affected site and still have a catastrophic impact on homes.

5. DRAINAGE ISSUES

Leaking drains can result in a large volume of water seeping into the ground. This can cause the soil to become saturated, making the ground unstable. High volumes of water can also wash away the soil beneath the foundations, leading to subsidence.

BUILDINGS INSURANCE SUBSIDENCE

If you have encountered subsidence in any form, you are likely to already know what a traumatic experience it can be to get the problem put right. Even in mild cases that can be remedied relatively easily, the process can still be harrowing. Then when the problem is fixed, the difficulty you are likely to have finding house insurance with subsidence history remains.

Subsidence house insurance can be a nightmare to find at a reasonable price but because of the costs involved with fixing a subsidence issue, it is vital that you find cover. At Homeprotect we aim to give you a competitive quote for buildings insurance with subsidence cover, even if you have had problems with subsidence in the past. We base your house insurance subsidence quote on the risk your house is at now, not at the risk it faced while still subsiding.