Subsidence

Structural Inspections & Structural Surveys

If your home has any indications of subsidence, it may be a good idea to get an expert to look at it.

Possible indications of subsidence can be any of the following:

  1. Cracks appearing in the walls.
  2. Walls leaning or bulging outwards.
  3. Doors and/or windows becoming difficult to open and close (because the shape of the frame is undergoing small changes).
  4. General movement of the building.

Other factors

While the above are signs of subsidence they can also be caused by other factors. An initial thought might be to just leave it as is and try not to think about it (put your head in the sand). In some cases there may be no problem at all, but if subsidence is occurring it may progressively get worse. Hence a survey from a Structural Engineer might be money well spent.

Sometimes a small amount of subsidence occurs when a building is first erected. The building quickly settles to a static state and no further movement occurs. Often in these situations no action is needed and everything should be fine.

Chalk soils

Properties built on chalk soils are usually very stable as the chalk is compact and relatively shallow foundations are often adequate. Properties built on clay soils can be more of a problem, especially if the foundations are not deep enough. Clay soils shrink and expand depending on the amount of water in the subsoil. This varies through summer and winter as the water content increases and decreases.

Large trees

Large trees have an effect on water content as they are continually sucking moisture out of the soil. Planting trees near a building can have a detrimental effect over time, as they gradually get larger, and suck out ever increasing amounts of water which makes the surrounding soil dryer. Removing large trees can also have a detrimental effect as all of a sudden the water is not being sucked out and so the water content in the soil will increase.

Leaking drains

Leaking drains is another common cause of subsidence. As the soil becomes more waterlogged it expands and it can also start moving, resulting in corresponding movement of any buildings in the near vicinity.

Mining

Another cause of subsidence is old mining activity. Some old mines are a honeycomb of empty chambers deep underground often connected to the surface by a vertical mine shaft. A gradual collapsing of parts of the mine can cause significant problems particularly those parts that are close to the surface.

If a subsidence problem is allowed to deteriorate the cost of repair can become very large. In the worst cases the building might need to be 'underpinned'. This involves a group of workmen digging narrow trenches one by one under the building and filling them with cement. This is done progressively in stages until there is enough concrete to provide adequate new foundations to stabilize the building. This can be quite costly and in some extreme cases it is sometimes more economical to just knock the property down and start again but with more substantial foundations.

Insurance

Chartered Surveyors can look at a property and give advice but in most cases a Structural Engineer will usually be more experienced.

The Local Surveyors Direct Website provides a quick way to find Structural Engineers who should be able to help you (www.localsurveyorsdirect.co.uk). On this price comparison website you just enter your postcode and immediately you will be given multiple estimates together with full contact details of the Structural Engineers and Building Surveyors who cover your area. Should you wish to place an order you would just deal directly with your chosen supplier. There is no middleman slowing things down or taking a cut of your money. With a professional assessment in place you could seek out home insurance quotes


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