This subsidence project was completed on behalf of a private client via an ‘escape of water’ peril clause on a house insurance policy. The extension to the rear of a terraced property was found to be rotating away from the original dwelling where cracking of over 8mm had formed through previous repairs between the junction of both buildings.
The primary constraint in executing the works was access. Not only was the property terraced, but it was located on a busy narrow street in the inner city. Therefore, the only route to the works area was through the front door. Considering these limitations, grundomat piles was chosen as they could be easily and safely installed in such restricted access areas and the required loadings were very low.
Grundomat uses impacts of relatively high frequency but low intensity using a man portable bottom driven cylindrical air hammer. It can be applied where rig access is wholly restricted and/or loads are very low (≤50kN) and/or where the pile lengths will be less than about 8 meters. The piles were driven to refusal and supported a series of reinforced concrete straddle beams constructed beneath the foundation.
All defective drains in the vicinity of the area of distress were repaired or replaced to current standards and tested as per Technical Guidance Document H Drainage and Waste Water Disposal. Hard-standing surfaces were made good locally on completion.