The project involved the addition of two storeys onto an existing three storey 1960’s library building. We found that Colliers Wood London Underground station extended under the site at a depth of approximately 6 metres. As a result, the existing building had been founded on pad footings and the bearing pressure had been limited to 110kN per square metre.
However, although we were able to demonstrate to LUL that it was feasible to add the extra storeys without increasing the foundation pressure by load trade-off the project was not economically viable. The costs for monitoring and surveying the underground station were prohibitive on such a small project.