Projects / Walford Road, N16
REAR MANSARD · HACKNEY
A rear mansard, approved first time
Two rooms and a WC at the back of an 1880s terrace, with both party walls raised.
FIG. 1 · Existing roof space and the rear mansard, same section line. Drag the line, use the arrow keys, or press a button.
The brief
Sunita and James both work from home three days a week and were taking calls from the bedroom. They wanted two rooms in the roof, a study and a spare bedroom, and a WC so nobody had to come downstairs.
What made it tricky
- Height. There was 2.05 m from the joists to the ridge, too low for a rear dormer to give two proper rooms. A mansard lifts the whole back of the roof.
- Planning. The council wanted the front roof slope left exactly as it was, the mansard at the back only, at about 70 degrees, in natural slate, with the windows as dormers within the slope. Niamh drew the rear elevation three times before the application went in.
- Party walls. Both party walls had to be raised to meet the new roof. That meant party structure notices to both neighbours, with two months' notice. One appointed their own surveyor, so there were two surveyors and an award.
What we built
A rear mansard at 70 degrees in natural slate with two timber windows, a flat roof in single-ply membrane with the insulation above the deck, and both party walls raised in matching brick. Inside, a 3.6 m by 3.1 m study, a 3.6 m by 2.8 m bedroom and a WC with a basin, off a small landing at the top of a new straight stair.
Niamh redrew the back elevation three times before the application went in, which felt slow at the time. It was approved first time, and our neighbour's surveyor didn't ask for a single change.
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