Shrinkable clay soils
Some
types of clay shrink dramatically when they dry out causing serious subsidence.
In the last 30 years insurance claims for subsidence as a result of shrinkable
clay soils have cost the UK economy over £8·2bn.
Over 70% of the cost of subsidence has occurred in the last 15 years.
Hotter dryer summers, as predicted by climate change models, will make subsidence more common in the UK.
Subsidence is caused when clays soils dry out in droughts or their moisture is removed by tree roots.
Some clays are very much worse than others. The British Geological Survey has made maps showing areas of shrinkable clay hazard in Great Britain.
House builders can use these maps to built houses with subsidence resistant foundations in affected areas, and structural engineers use them to reduce subsidence problems in older houses.
Related links
External links