Mansard
/MAN-sard/
Also known as: mansard roof, mansard loft, mansard conversion, mansard extension
Definition
A roof form with two slopes on each side - a steep lower slope (typically 70 degrees or more) and a shallower upper slope. The steep lower slope creates usable internal space and is often clad in slate or zinc with dormer windows. Common in London terraced houses as a loft extension form.
In Practice
Mansard loft conversions are popular in London because they maximise usable floor area within the roof. They typically require planning permission as they substantially change the roof's appearance. A mansard to a terraced house often incorporates a flat section at the top, with the steep rear slope in slate or zinc and one or more rear dormers. The structural frame is usually timber or steel sitting on the existing party walls.
UK Building Regulations
Approved Document A - Structure
Mansard loft conversions almost always require full planning permission and a party wall award where the building is terraced or semi-detached. Structural engineer input is essential.
See Also