A subterranean development below Pump Court as part of the refurbishment and extension of the Grade I listed Dining Hall at Jesus College, Cambridge.
Dating back to the founding of the Benedictine convent of St Mary and St Radegund in the 12th Century, the Grade I listed buildings in Pump Court have remained virtually untouched ever since. The refurbishment and extension of the Old Kitchens and Dining Hall will accommodate the growing numbers of college members and visitors while also improving services, circulation, and accessibility to the buildings. Beneath, the new subterranean extension will house additional plant rooms, stores, and a wine cellar, and it will connect to the Upper Hall with a double-height, single-storey extension, and a three-storey extension.
The basement is formed of a perimeter piled wall to maximise the useable space beneath Pump Court, which is bounded on three sides by existing structures. A top-down construction methodology was adopted due to the site constraints, with all excavated material removed from Pump Court via a small arched pedestrian route. Utilising this approach has enabled ground movements adjacent to the historic structures to be minimised, thus mitigating the risk of damage to the listed fabric.
Close collaboration with the main contractor and the basement sub-contractor enabled a temporary works scheme which optimised the programme whilst working within the site’s complex constraints. This allowed the works to form the basement beneath the piazza slab to run concurrently with those above it and permit the new extensions above to progress simultaneously.
The existing ground floor has been lowered to increase headroom and provide adequate space for additional services in the new kitchen area. This was made possible through the underpinning of the historic walls which were up to one metre thick in parts and rubble filled. The existing Dining Hall floor has been strengthened through the installation of steel beams which provides a flexible, uninterrupted space for the new kitchen and associated storage space beneath. Working on a building of this age, close collaboration with the architect was vital to evaluate the proposed works and adapt them to what was uncovered on site as the demolition works took place.
The soffit of the basement sits 1.5m below the landscaped Piazza. Sustainable drainage systems (SuDS) are incorporated into the surface water drainage strategy, in accordance with planning requirements, to reduce the impact of urbanisation on watercourse flows. This includes a below-ground storage tank, situated within the 1.5m build-up, and paved over with the existing Yorkstone paving slabs and cobbles to tie in with the rest of the college’s hard landscaping.
The basement extension has been carried out whilst significant works were undergoing elsewhere within the College.
