Subsidence In Buildings - Planning Ahead

Much of London and the suburbs are built on a shrinkable clay soil, which is prone to excessive shrinkage during hot dry summers.

Planting trees close to a building will increase the rate of shrinkage in the clay around the foundations, leading to a downward movement in the structure.  In extreme circumstances this will lead to subsidence producing cracks in the building, distortion to door and window openings and slopes in floors.

It is important that your property is insured against the risks of subsidence but if this occurs the Insurers are likely to embark on a lengthy process of monitoring the building (sometimes 18-24 months) before making a decision on the type repairs.

To avoid reaching this stage there are certain things you can plan for the early spring:

1. Do not plant a fast-growing tree close to your house. A safe distance equates to its anticipated mature height;
2. Where existing trees are growing within such a distance, then carry-out periodic pruning to ensure that it does not reach full height.

You will need consent from the Local Authority before pruning or removing a tree protected by a Tree Preservation Order.

We do not recommend the removal of some mature trees as this could cause the sub soil to swell and lead to foundation heave; this might produce worse damage than would be encountered through subsidence.