How much does subsidence devalue a property

Subsidence is a common problem which can affect some properties. Here we will look at the meaning of subsidence and at how much does subsidence devalue a property.

What is the meaning of subsidence?

Subsidence means a situation where the ground beneath a house sinks and so affects the property foundations.

Subsidence can be minor or major subsidence. Serious subsidence can affect the structural safety of a property.

Subsidence can be current or historical subsidence. Current subsidence means that the soil beneath is still subsiding and affecting the property. With historical subsidence the ground beneath has stopped subsiding. Historic subsidence means it is usually much less serious.

Some signs of subsidence include leaning walls, substantial cracks in walls, sloping floors, and doors or windows that do not fit properly. It can affect an extension as well as a main property.

What causes subsidence?

House subsidence can be caused by a number of different things.

Subsidence can be caused by the type of ground beneath a property’s foundations. Subsidence occurs sometimes in clay soil areas. Clay soil is not a more stable soil. Clay soils absorb water in wet weather and expand and then in dry weather dry out and contract. Sandy or silty soils can also be a factor in subsidence.

Subsidence can be caused by flooding. A broken or leaking pipe or sewer can also cause subsidence. Subsidence can be caused by long periods of dry weather leading to a fall in the water table and where the ground dries out and compacts.

Large trees, large tree roots and plants which take moisture from the ground are also sometimes believed to cause subsidence.

Subsidence can be caused by underground mining for coal or other minerals in an area with mining history.

Subsidence can also be caused by some kind of building defect or construction problem. For example, building land which has not been prepared properly or where the foundations are inadequate to support the weight of the building. 

How to fix subsidence

The first step in rectifying a property with subsidence is to fix the cause of the subsidence to prevent it recurring. For example to deal with the cause of flooding, fix a broken pipe or tree issues.

Rectifying subsidence may also require the repair and/or reinforcement of the property’s existing foundations. Fixing subsidence may call for some form of underpinning.

Subsidence and underpinning

There are several different types of underpinning.

Mass concrete underpinning means that the existing soil from underneath the property’s existing foundations is removed and replaced with concrete. This may be needed under a single wall or several walls.

Mass concrete underpinning is usually the cheapest way to fix subsidence.

Other methods of fixing subsidence include piled or mini-piled underpinning, beam and base underpinning or resin injection or grout injection which are types of soil strengthening.

Once the subsidence has stopped you will also need to repair the damage caused by the subsidence. For example, to repair the cracks that subsidence has caused or further structural work.

It is essential to take further advice from a surveyor, structural engineer or builder on the best way to deal with subsidence and any underpinning required. They may recommend a property survey or a full structural survey.

Does subsidence devalue a property?

Subsidence can devalue a property. By how much subsidence devalues a property will depend on how bad the subsidence is.

Minor subsidence may not devalue a property very much at all. Severe subsidence may devalue a property by a significant amount. Serious subsidence may mean a property is unsaleable. In other words serious subsidence may devalue a property by 100%.

There are several reasons why subsidence may devalue a property.

Firstly, many prospective buyers will not want to buy a house with subsidence issues at all. A house with subsidence is usually considered a problem property in the housing market.

Potential buyers who are prepared to buy a house with subsidence issues will usually expect a reduction from the asking price to allow for the cost of repairing the subsidence. They will not want to pay full market value for the property.

The main reason subsidence devalues a property is because buyers may not be able to get a mortgage. A property with subsidence may be unmortgageable. This is likely to mean that only a cash buyer is able to buy it. Cash buyers such as property developers are likely to expect to buy the property for less than its full value or normal purchase price.

Does underpinning devalue a property? In most cases subsidence should not devalue a previously underpinned house if the subsidence has been professionally diagnosed by a structural engineer and properly fixed.

By how much does subsidence devalue a property?

It is very difficult to estimate by how much subsidence devalues a property. It depends on the extent of the subsidence and the cost of repairing it.

Subsidence will devalue a property by at least the cost of fixing the subsidence and possibly more on top due to the costs involved.

For example, if a property with a market value of £300,000 has a subsidence problem which will cost £30,000 to fix then the subsidence will devalue the property by at least £30,000, or 10%, compared to a similar property.

This report says that the level of severity will determine how much subsidence devalues a house with subsidence, but generally speaking, you could find that it decreases the market value of your home by as much as 20%.

According to figures from Checkatrade the average costs of mass concrete underpinning are  £1,500 per m2, of beam and base underpinning £2,000 per m2 on average and piling £2,600 per m2 on average.

According to My Job Quote the average cost of underpinning a house will be £6,000-£21,000, but this will vary depending on the underpinning method, size of the property, and its current state.

Subsidence and house insurance

House insurance policies will not cover the amount by which subsidence devalues a house.

Buildings insurance policies will generally not cover the cost of fixing a subsidence problem.

Buildings insurance policies will normally cover subsidence claims for the cost of fixing the damage caused by subsidence although there may be a large insurance excess to pay depending on the insurance company.

Further advice on subsidence

It is recommended to consult a surveyor or structural engineer to provide expert advice and suggest exactly how much does subsidence devalue your property. They (or an estate agent) will estimate the property value with subsidence and of the underpinned property. They will also estimate how much fixing the subsidence is likely to cost. You will then be able to see how much exactly subsidence affects the value of your property.