Project Description

Abbey Pynford were approached by Mulaley on behalf of the London Borough of Hillingdon to develop an underpinning scheme for a rear section in 2 Y shaped blocks of flats where the section to be underpinned is supported on 6 reinforced concrete columns.

The difficulty in this project was to maintain the stability of the building while underpinning only 6 no 300mm square columns. Traditional methods of propping walls and removing the temporary supports after would not work on this project.

Abbey Pynford devised a method where by each column would need to have the load removed and be supported by a temporary mabey propping system. The column could then have the underpinning raft installed in a specific sequence, with only 2 columns being underpinned at any one time. This meant each block has a 3 phase underpinning sequence.


This complicated job involving piling, jacking and RC works to rear elevations of two 3 story block of flats was successfully completed on time, with very little or no disturbance to the residents who remained in the flats during the duration of the works.

Nick Tidman, Contracts Manager

Construction Phase Highlights

The first stage is to break out the existing slab and reduce level to formation level ready for the piling rig. The mini piling rig used is designed to install piles within existing houses so was ideal for the low ceiling within the project. The piles were install to depth of 15 meters and were 300mm diameter.

Jacking load into the existing columns

The operation before we could start to re case the reinforced concrete slab that would support the building. A special bonding resin is coated around the steel column which grips to the new RC slab to support the building above.

First section of the slab cast and the reinforcement in place for the second pour.

The shuttering has been installed and the sika-dur bonding resin is placed round the steel column beneath the existing Reinforced concrete column ready for the new concrete raft to be cast.