An extension with a rooflight at the ridge
A detached pitched-roof extension provides additional living space to a 1950s brick dormer bungalow, linked to it by a new single-storey, flatroofed entrance lobby. The extension contains two large living spaces, one on each floor, and a study.
The ground-floor living space is designed as a cool summer room with a relatively low ceiling (2,250mm) and large areas of glazing that open out to a sunken, brick-walled courtyard.
In contrast, the upper-floor living space, reached by means of a timber-clad staircase, is light and lofty, with a ceiling that follows the pitch of the roof and rises to a continuous rooflight set along the ridge and raised up on polyester powdercoated aluminium upstands.
The room is additionally lit by a large 'folded' window; the top pane follows the pitch of the roof to meet a lower pane, which extends vertically to just below the eaves.
The extension is clad with an outer leaf of brickwork which rises above the eaves to conceal gutters made of seamless extruded aluminium box-sections with welded corners. They drain to internal downpipes and are covered to prevent blockages. The internal leaf is of timber studwork clad with ply and plasterboard.
The structure is a steel frame of 203 x 203mm UC columns supporting 203 x 203mm UC rafters. On each side the rafters terminate just below the rooflight upstand and are welded to a continuous 230 x 75mm PFC. The rooflight upstand structure - a series of SHS posts and angles - is welded to the top flanges of the PFCs.
The patent-glazed rooflight slopes to one side where slots in the upstand allow rainwater to drain on to the roof.