When you spot cracks appearing in your home, it can be a worrying discovery indeed. No cracks should ever be ignored, but they are not necessarily indications of a subsidence issue. Typically subsidence cracks are tapered in appearance and spread diagonally across your walls, often originating from door or window frames. Subsidence cracks will open quite wide and will not close up naturally on their own. Cracks that close up on their own could be forming as part of your home's seasonal expansion and contraction, and may not be anything to worry about. This said, you should always seek professional advice when you notice any cracks appear.
Is underpinning always necessary?
Underpinning is not always necessary to rectify a subsidence issue, and is increasingly being used only as a last resort. There are a number of other options that might be open to you, depending on the individual circumstances of your subsidence issue. Usually, once you have contacted your underpinned house insurance provider, a period of observation and investigation will commence to diagnose the issue properly. his monitoring may need to be done over long periods to make sure that the movement is ongoing, so getting a quick-fix might be out of the question. Consulting engineers may be called in to help determine the best course of action to take in order to rectify any structural issues.
There are two particular situations where underpinning work should not be carried out. The first of these is if the ground movement that caused any damage has stopped and is unlikely to reoccur. Underpinning is also inappropriate when the rate and final extent of any damage is not likely to impair structural strength or integrity and will not threaten stability during the building's expected life-span.
In both cases, repairing and redecorating after damage has occurred iess less expensive and less traumatic for the building's occupants.
New and old buildings
If your building is new then it is a good idea to consult the builder and ask them to inspect the property, but older properties will not come with this option. There are a number of common causes of subsidence, and there could be additional exacerbating factors. In the South East of England, the clay-rich soils mean that clay shrinkage is a likely candidate after extended hot dry periods. This can also be the case elsewhere, but it is particularly rife in areas around the Thames (where it is now and where it used to be historically). Settlement of soft ground can cause subsidence issues, particularly where leaking drains or pipes are an issue. No matter what type of subsidence you encounter, if underpinning is required then you will have to seek out underpinned insurance in the future.
Where subsidence issues are being caused or aggravated by tree root incursion, instead of immediate underpinning you may be able to mitigate further damage with careful tree management. Removal of trees completely is not always a good idea, as this can lead to other severe ground movement problems down the line, but you will need to consult a professional arboriculturist or similar before taking action. Sometimes tree pollarding is used to control tree growth and this might be preferable to the invasive and expensive practice of underpinning.
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