Patrick Harrison's flat working details
A new single-storey extension - living and dining area, kitchen and study - has been formed between two boundary walls at the rear of a Grade A-listed building in Edinburgh's New Town. The kitchen and study are covered with a flat roof; living and dining areas are covered by a curved barrel vault flanked at each side by a pitched rooflight which rests on the higher stone boundary walls. A pair of box gutters, set between the vault and the rooflights, projects beyond the gable and terminates in a spout with three stainless-steel chains which direct rainwater into a gulley.
The curved gable of the barrel vault is glazed with a 'half-moon' fanlight above glazed sliding doors and shutters which slide into the wall cavity. The fanlight has an insulated ply shutter with a piano hinge at the base and a cable and pulley at the top which allows it to be raised and lowered. It rests on the top of the beech soffit when not in use.
The barrel vault is formed of curved 203 x 133mm universal beams and insulated timber joists covered with a lead roof with rolled joints. It projects beyond the fanlight, supported on tapered T-sections welded to the beams. The gutter is a continuous pre-formed aluminium extrusion.
The fanlight - three curved, fixed, double-glazed units in a redwood frame - rests on an exposed 200 x 90mm steel channel. The glazed doors and beechveneered ply shutters are set back below it. They slide on floor tracks into a recess between a new outer leaf of stone - reused from an original wall - and blockwork and an inner leaf of studwork and plasterboard.