Purkelly's full service in action
Client: The consulting engineer
Purkelly provided a full range of services including piled underpinning, reinstatement and superstructure repairs for this contract to an extension at a large detached house. The emphasis was on quality throughout.
Park Road New Barnet, Herts
Subsidence had affected the rear single storey extension at the property. Shallow site investigations identified the cause - shrinkage of the underlying London Clay strata due to the influence of the roots of adjacent conifer trees.
The consulting engineers specified a piled raft underpinning system to be designed by the contractor. Purkelly were awarded the piling design and construction contract as well as substantial superstructure reinstatement and repairs.
We opted for 200 mm diameter auger bored piles installed to 9.0 m with a top 3.0 m sleeve for heave protection. 8 No. piles were installed with the bores remaining open and dry prior to concreting, which was carried out on a daily basis.
The piles were used with a 250 mm thick RC flat slab constructed continuous through the external walls which were temporarily supported by steel jacks. Pockets were formed in the slab using polystyrene jack protection. The jacks were removed on completion to maintain full heave protection.
Heave protection to the raft slab was provided by installing 160 mm clayboard below the slab.
