A builder in Kent attempted to excavate traditional trench fill foundations for an extension, but unfortunately due to the presence of a clay subsoil and the location of a nearby tree, the Local Authority Building Inspector insisted that the trenches be dug to a depth in excess of 2.5m or change the foundation to a fully engineered foundation solution such as piling.
Initially we visited site and provided a free estimate for the works based upon a scheme of piles and ground beams. Upon receipt of his instructions to proceed, our in house Chartered Structural Engineer prepared a design for the piles and ground beams and submitted this to the Local Authority for approval.
We then mobilised our limited access piling rig and installed eight no. 300mm dia open augered piles to a depth of 8m which in turn were linked by a series of 450mm x 450mm rc ground beams.
The piles took in nominal ground water once drilled, but remained stable. We therefore tremmie grouted the piles with a 2 : 1 sand : cement grout to displace the ground water from the piles. Concrete test cubes were taken to confirm the strength of the grout and the piles were integrity tested.
Full anti heave precautions were installed to the piles and ground beams.
Upon completion of the works, we issued our 12 year Defects Insurance Guarantee and they were completed with only a small delay to the overall programme.