What is Subsidence?
Subsidence is a change in the condition of the ground on which a building is supported. It can result in crack-damage to walls and ceilings, distortion to door and window openings and in extreme circumstances, fractures to pipes and other services.
In London and the South East, this damage most commonly occurs to buildings founded on shrinkable clay sub-soils, during periods of very dry weather. This is usually where roots from trees and large shrubs grow beneath foundations, extracting even more moisture and causing the clay to shrink, and the foundations to move. Subsidence can occur due to other factors as well, such as the softening or erosion of soil by water from a leaking pipe or drain.
When Subsidence to a building is suspected, a thorough investigation by an experienced Chartered Structural Engineer or Chartered Building Surveyor is required to diagnose the cause, and accurately identify the area of foundation movement. Once this has been established, a course of action can be decided and the correct remedial action can commence.
What is Heave?
Heave is also a change in the condition of the ground on which a building is supported, affecting only clay soils. It can produce a similar degree of crack-damage, although the pattern of cracking may be different.
All vegetation takes up moisture from the soil in which it grows, some plants more than others. Where established trees or vegetation have existed for a long period of time, the level of moisture in the surrounding soil remains relatively stable over the long-term (subject only to seasonal fluctuations). If such vegetation is suddenly removed, excess water in the soil is no longer taken-up and clay soils will do the opposite of shrink, they will swell and may ‘push-up’ any structure built upon them. Investigation of this problem involves identifying the soil-type, and also any external factors which have influenced the sub-strata, including the removal of trees and vegetation. A solution then needs to be designed.
Where subsidence is identified (see above), removal of nearby trees is often, but not always, the best course of action – the risk of ‘heave’ is one reason why expert advice should be sought. On clay subsoils in particular, trees and vegetation require considered management.
Since 1978 our Chartered Structural Engineers and Chartered Building Surveyors have been successfully resolving the problems of subsidence damage to domestic and commercial properties across London and the South East.
We have built an unrivalled wealth of experience and a highly-regarded reputation in this specialised field. Our directors employment history includes Loss Adjusting experience and we have a comprehensive understanding of the many issues relating to insurance cover for subsidence, as well as an in-depth knowledge of the technical aspects of investigation and remedial works.
We have been appointed as Expert Witnesses in a variety of difficult claims and have produced independent Reports for the Financial Services Insurance Ombudsman.
Where the investigation of, and solution to a subsidence problem is concerned, it makes no difference who is funding the cost; our opinion will reflect the structural conditions encountered.
We work with many major, and specialist firms of Loss Adjusters resolving personal and commercial subsidence insurance claims; however, our services remain independent - and we will always provide accurate, thorough, unbiased advice.