Any new build project or renovation may need a site investigation, mainly to check for the possibility of subsidence, which could cause expensive problems. A site survey using technology such as soil testing, hydraulic testing of pipes and measurement of crack movement can head off a lot of issues in the future.
Subsidence is a very common problem; it can have a number of causes including shrinkage of clay soil when dry (and expansion when wet), undermining of buildings by tree roots, and water leaks causing softening of the ground. Even the weight of buildings themselves can cause settling, as can mining activity.
Surveys
A site survey can detect many of these problems. Usually taking a few hours to complete, a site survey often involves drilling bore holes, either externally or internally, collecting samples, and using cameras to investigate pipework. Hydraulic testing can be done by blocking off a drain run with an inflatable bag or bung and filling it with water, so any leakage and the rate that the water is seeping into the ground can be seen and recorded.
Before building work is done, soil testing can determine the properties and bearing capacities of the soil such as water content and compressibility so foundations can be designed correctly, including for instance the best class of concrete to use.
In existing buildings, measuring equipment can be fitted to check levelling and crack expansion. Often a year of data will deliver seasonal variation data which will suggest how remedial work could be carried out.
It’s often a good idea to carry out this sort of work after flooding to check that the ground has stabilised.
A geotechnical survey carried out before building work can reveal the presence of any ground contamination which may require remedial work before building commences. Investigating the history of the site will often suggest the possibility of contamination, but a second phase of intrusive investigation is often needed to confirm any contamination, and suggest methods of remediation and monitoring.
A site investigation can include various levels of reporting from the strictly factual to the interpretive, and can include plans, logs, testing results and assessment. Your surveyor can work with loss adjusters, insurers and developers, as well as individual homeowners, structural engineers and architects to deliver the facts about the land and property you really need to know!
See also: How Can a Chartered Surveyor Help Your Property Purchase?
