Cost Of Repairing Subsidence

A guide of the procedures for correcting subsidence, what causes it and how much it costs to rectify.

Duration:
2-6 Weeks
Avg price:
£6,250

Introduction

This article will detail the steps that you need to take to fix subsidence once that you have recognised that the condition exists within your property. It will look at how it manifests, the causes of the subsidence, and how to effectively fix it.



Costs involved with fixing subsidence

The worst-case scenario of subsidence, your house may need to have substantial underpinning, which is both costly and disruptive, with prices reaching £50,000 in certain cases. The Royal Institution of Chartered Surveyors (RICS) quotes that less than 10% of properties that are affected by subsidence need this amount of work with underpinning. Claims data from the Association of British Insurers implies that in the majority cases, the price of correcting subsidence is a lot lower, as the average pay-out is about £6,250.


What subsidence repair entails

Subsidence occurs when areas of the ground underneath a house sink. This is the major supporting feature, and if the ground moves, it results in a lowering of the foundations of the property, which can then become uneven. It’s especially challenging when the ground underneath your property is sinking at different rates.

Subsidence is the opposite of an allied condition called “heave”, which is where segments of the ground underneath your property move upwards forcing the foundations higher. It’s also different from a landslip or landslide; this is where the ground your property was constructed on moves down a slope or is swept away by heavy rain.

The fixing of subsidence can be very simple or very complex, depending upon the underlying reasons for the cause in the first place. The job may require tools as simple as a spade and reinforcing materials to the need for major ground working tools and the shifting and replacing the moving material.


Other jobs to tackle

If you’re burdened with a severe case of subsidence, you might need to look at the reasons for the change and deal with the cause. This might mean that you identify and have to either move a tree’s roots or install a waterway to ensure that soil remains moist but not washed away.


General advice when fixing subsidence

While subsidence can have a combination of complex reasons, there are just a few reasons why it should suddenly occur. These include:

  • Trees Too Close - If you have trees or even big bushes planted too close to your property, they can trigger subsidence as the plant drains all the moisture in the soil causing it to desiccate and collapse. It’s estimated that around 70% of all subsidence issues are a result of plant roots soaking up the moisture out of the soil.
  • Clay Base - This type of ground material changes considerably with different weather. When it’s hot and dry, it can shrink significantly, which then makes it crack and shift and then there is a greater risk of it sinking.
  • Prolonged Drought - If you live somewhere that is prone to drought or a lack of rainfall, then the soil could dry out, which increases the chance of subsidence.
  • Drainage Leaks - A leaking drain or water main can soften the soil, or wash it away, causing sinkage in the soil.
  • Age and Construction - If you live in an older/period property, there may be a larger chance of subsidence occurring as these houses may have much shallower foundations than a new-built property. However, the good thing about this is that older properties tend to be built from bricks and lime mortar, which makes them more flexible and less likely to be damaged by the ground moving beneath them.
  • Mining Work - This is a familiar cause of subsidence. If your property has been built near to a previous quarry or mine, then it could get unstable as the material used to fill the site moves as it decays. Your property could also be affected if mining activity happens close by too.

Many of these factors mean that conditions can change quite quickly and where you may not have had any history of subsidence, you could find that it starts to occur should local circumstances occur. Many cases of subsidence also come as a result of the ground under your home changing so you will have to do something with that.

The major explanation of subsidence is the influence of the weight of the building. Where the property sinks ‘into’ the ground upon which it’s built, then this is generally revealing of incompetent design and construction.



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Sam J

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