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Subsidence Information
There are several causes of subsidence damage in buildings, however the primary cause is differential movement associated with drying of clay soils below the foundations. When a shrinkable clay soil looses moisture it shrinks. Depending on the characteristics of the clay and the degree of shrinkage, this can result in the downward movement of the foundation which may cause cracking in the super-structure. Moisture abstraction by vegetation is responsible in approximately 80% of subsidence claims and instances of damage increase significantly during hot dry summers.
The most common symptom of clay shrinkage subsidence is cracking in external and internal walls often effecting one area or part of a building. External cracking often follows mortar lines in a “step” sequence. Internal cracking is commonly visible in walls, above internal doors and ceilings and may mirror external crack locations.
If you notice cracking in your property you should notify your buildings insurer as soon as possible and they will arrange for an expert assessor to visit your property. Detailed site investigations to determine the cause of the cracking may be required, however this depends on the suspected cause as not all cracking is due to subsidence.
If the damage is concluded to be due to clay shrinkage and trees are identified as a potential causal factor, an Arboricultural report is normally required to determine which trees or other vegetation is responsible and what measures are necessary to abate their influence. Removal may be necessary, but not always. It is essential qualified arboricultural advice is sought to ensure appropriate vegetation management and long term stability. Inappropriate vegetation management can in some circumstances casue ‘heave’ which can result in uncontrollable and severe damage.
If you are a property owner and would like advice please contact us and we’ll be happy to advise you.
