Subsidence damage occurs when movement in the ground causes movement of the building foundations. The damage often shows up as cracks in walls or ceilings, often around door or window openings and wider at the top than the bottom. Doors and windows may also stick.
Subsidence most commonly occurs when clay soil under the foundations dries up and shrinks, frequently due to moisture extraction by the roots of nearby trees. This type of subsidence typically occurs in the summer following hot, dry weather. The second most common cause is leakage from underground pipes washing away or softening the soil beneath the foundations.
Another less common form of ground movement is heave. This occurs when the ground swells – often when moisture levels increase in a clay soil after removal of trees.
In many cases subsidence damage can be repaired relatively easily and effectively and without foundation work. This is usually after the cause has been addressed which will typically involve some tree work or repair of a leaking service pipe. In a small proportion of cases, normally where the cause cannot be removed, it is necessary to undertake foundation works.
Site investigations are investigations carried out to establish the type and condition of the foundations and soil beneath the foundations. The investigations are carried out to determine the cause of the damage to the property. These can consist of trial pits – small pits dug into the ground and Boreholes – a deeper hole drilled into the ground to obtain soil / root samples for study.
Buildings can also move and be damaged by other factors including the movement of old coal, flint and chalk mine working and the collapse of shafts and adits; natural features such as sinkholes; infilled quarries; peat and soft soil and unstable slopes.
Having over 1000 subsidence investigations under its belt and providing services to one of the UKs largest insurers Geoinvestigate can be relied upon to carry out a reliable and highly professional assessment of the causes of building subsidence and movement.