Visitor Centre, White Cliffs of Dover van Heyningen & Haward Architects
To reduce construction work on site, the visitor centre was partly prefabricated. It consists of eight rows of six precast concrete columns which slot into concrete sockets in a cast in-situ ground slab. The exterior walls are set back on all sides from the outer row of columns to provide a loggia beneath an overhanging roof; it acts as a covered waiting area, sheltering the building from the weather, and on the south side it shelters the glazed facade from solar gain.
The centre pairs of columns, 152mm square in section, support a barrel- vaulted polycarbonate rooflight which runs the length of the building. These columns are tied with a tubular strut. The outer corner columns are 200mm square in section and are triangulated with stainless-steel tie rods which allow them to span the greater distance and resist wind loads.
The columns were cast with cruciform heads on which rest a series of paired 275 x 100mm Douglas Fir rafters which are bolted to them with exposed stainless-steel fixing bolts. A series of 200 x 100mm purlins rest on the rafters, covered with a ply roof-deck and an Erisco-Bauder turf roof system. On the loggia the columns are encased with brick to the eaves. Where roof drainage is required, one side of the brick encasement is omitted to make a recess for an aluminium rainwater pipe, fixed back to the column.
On the north side, the columns are encased in a breathing wall clad with cedar weatherboard on the outside and a double layer of plasterboard on the inside. On the south side, the columns are set between Douglas Fir mullions, spaced apart from them by 100 x 90mm timber battens clad with ply.