Large underground basment extension beneath a large Victorian house in Kensington which already had a basement beneath.
Founded in gravels into the water table over a deeper clay layer beneath. Combination of two stage underpinning and contiguous piled wall with injection grouting to mitigate water ingress.
Seth Stein Architects
This project involved the extensive refurbishment of a four storey Victorian masonry building in Kensington. In order to create a new basement below the lower ground level, the project required the temporary support of the existing internal structure on a system of reinforced concrete underpin beams on piles. External and party walls were underpinned in two levels as excavation progressed, meanwhile contiguous piles were used as temporary retaining walls for excavations outside the footprint of the building. A new watertight reinforced concrete box was then constructed underneath.
Particular care was needed to control any movements of the fragile masonry fabric during construction as the building shared a party wall with an adjacent building.
Much of the upper internal fabric of the building was then rebuilt or repaired as part of the works, together with extensive remodelling and repair of the external envelope to stabilise and conserve the building for the future.