Watergate Farm, North Oxfordshire by James Gorst Architects
James Gorst Architects has completed the first phase of a project set around a courtyard on a farm in north Oxfordshire.
James Gorst Architects
Phase I completed
The work has seen the restoration and conversion of an existing stone barn to become a painting studio, and the construction of a new building to provide a large car port, farm offices, storeroom and workshop, with a staff flat above. A second phase will complete the courtyard, linking the original farmhouse to an adjacent barn to form one long house.
The eastern wall of the studio barn was found to be structurally unsound and was rebuilt in rubble stone. The roof has been carefully uncovered, rotten timbers replaced and repairs stitched in, retaining as much of the original structure as possible — with care taken to maintain the uneven ridgeline.
The barn walls are lined internally throughout with 60mm insulating lime render and the floor laid with a lime wearing screed.
The two large openings have been infilled with oak-clad insulated doors to the outside and a double-glazed unit to the courtyard, made to the largest width possible (3.2m x 4.5m high), behind oak sliding external shutters.
The footprint of the new building follows that of a pre-existing stone barn demolished in the 1970s. Forming the boundary between the meadow and the cultivated garden within, a stone wall wraps around the new building at ground-floor level, while the remainder of the lower floor and the whole of the upper floor is oak-clad over a timber frame.
Within, the utilitarian workspaces of the ground floor have lime-rendered walls and a lime screed floor, while the soffit of the first floor in-situ concrete slab is exposed. The first-floor living spaces are open to the pitched roof, with walls and ceilings entirely clad in oak-faced birch ply. The ply sheets provide bracing to the timber frame and avoid the need for roof ties.
Insulation is Foamglas to the ground-floor slab and masonry walls, with sheep’s wool infill to the timber frame. The complex has underfloor heating supplied by a large ground-source heat pump, with 3km of pipework laid horizontally in an adjoining field.
To ensure the stability of the oak cladding, Trada advised on the timber sections and fixings. The projecting horizontal rails are rebated around vertical timber supports at 400mm centres to which the recessed boarding is fixed, providing a ventilated cavity over a breather membrane.
The oak is left untreated to weather down to a silver-grey, providing tonal affinity with the local rubble stone (a mix of three stones laid in lime mortar) and the Welsh slate roofs.
Engineer Jane Wernick Associates designed the pitched timber roofs of both the studio flat and carport to span between their gables as deep trusses, inclined in the plane of the roof.
Continuous timber elements at the ridge and eaves act as the boom elements of the truss: compression at the ridge and tension at the eaves. Shear forces in the plane of the roof are transferred to the gables by a diaphragm of plywood panels, fixed to rafters and purlins.
The 12m-span carport roof is supported vertically on one edge by a rubble stone wall, while the opposite edge is propped by a series of horizontal steel struts.
Structural engineer Jane Wernick Associates Services engineer Environmental Engineering Partnership Quantity surveyors Baqus Sworn King (to Stage G), Gardiner & Theobald (Stage H+) Conservation consultant Conservation Constructions Timber consultant Trada Main contractor R Durtnell & Sons