A significant two-storey extension to an existing Grade II listed hall alongside the Grade I listed church of St John the Baptist, to provide a much larger community hall plus office space, meeting rooms and a café area. A basement storage area has been constructed beneath the footprint of the new extension. The existing stone boundary wall to the adjacent churchyard has been incorporated into the design and is exposed in the café area.
The structure is built within the flood zone of the River Windrush and is designed to protect against future flooding. A contiguous secant pile retaining wall was chosen for the basement construction with an internal concrete lining wall and cavity drain water proofing system. The basement slab was piled to resist uplift from ground water pressure.
Upon appointment and consultation with the contractor it became clear that a top down form of construction could save time on the overall programme. There was enough flexibility within the team and the design that we were able to redesign elements of the steel frame and ground floor to accommodate this alternative sequence of works.
The steel frame superstructure included a steep pitched portal frame to form the new hall which was partly exposed. The existing churchyard wall that formed one side boundary of the site was left exposed in the café space and was also used to support the roof structure over the café. A detailed inspection of the wall and its foundations was therefore required before it could be confirmed that it had sufficient capacity.
The project required close liaison with Historic England and the Church of England’s own Oxfordshire Diocesan Advisory Committee.