On this project the combination of Conservation Area constraints and an ambitious architectural concept resulted in an extremely challenging project and, as a consequence, the use of several innovative design and construction methods.
As the concept design developed the scheme resolved to an almost total redevelopment of the property, a 19th century semi-detached house with a generous rear garden. Key was the aim to double the internal floor area, primarily by downward development. Conservation area status resulted in the requirement to retain and support the majority of the buildings’ primary fabric, whilst the structural work progressed beneath and adjacent to the house.
The original building possessed a traditional half basement. The new house configuration retains this half basement, albeit with the floor level lowered to provide extremely generous headroom, whilst a new full basement floor a further 4.5m beneath extends several metres forward of the house and some 20m beyond the rear elevation. Total floor area is now in excess of 800sqm, with the new basement spaces lit via a combination of a deepened light-well, a new sunken garden, and expansive glazed skylighting.
Making the transition from the original fragile four storey masonry building, resting in brick corbelled footings, to a new pile supported six storey building with generous open plan spaces required ingenuity. Temporary piles were sunk as soon as the fabric was stabilised. These piles were used to support massive temporary works to the house above, thus enabling perimeter piling and the groundworks to commence – using up to three excavators loading ‘8-wheelers’ driven straight in from the road.