A retractable glazed roof on mews house
The three-storey mews building has a retractable glazed roof over the living room on the second floor. It maximises the amount of daylight entering the room below and, when open, changes it into a courtyard space; glazed doors and frameless glass walls link it to the roof garden. At night the glazed roof 'modulates artificial light internally and externally on to the roof garden'.
As shown in the assembly diagram, the upper floor is a steel frame set on existing universal beams. The roof structure consists of paired 152 x 76mm parallel flange channels (PFCs) set back-to-back and spaced apart with steel ferrules. The bases of the PFCs are lined with fibreboard to prevent cold bridging.
The retractable glazed roof consists of double-glazed argon-filled panels with an outer sheet of 6mm toughened glass and inner sheet of 6mm solar control glass, set in aluminium mullions. The roof is set in a perimeter frame of insulated steelwork. Code 4 lead flashings seal the junctions between the steelwork, the housing to the motor and worm gearbox, and the solid edges of the roof, which are covered with 20mm twocoat asphalt.
The glazed roof has a 5infinity pitch to avoid rainwater ponding and drains into a gutter which runs along the opening edge.
When the roof is closed the gutter tucks in beneath the overhanging coping to the rear blockwork wall. The coping is dressed with lead, formed to create drips along the edges, and weatherstrips to direct water into the gutter.
As an additional protection, a secondary gutter runs below it, fixed to the blockwork wall.Both gutters drain into a hopper and discharge onto a roof at the rear of the building.