The determining level of quality associated with the conventional mansard roof structure is its broken slope, with a long, steep lower segment and a reduced and flatter upper slope. This form takes its identify, and name belonging to the French designer Francois Mansart although he did not create it. ln traditional construction, the mansard's double slope rises from the eaves and is applied to each elevation of the building. When applied 1 ( only to opposing elevations, it is sometimes described as a gambrel or gabled mansard.
The term 'mansard' is now utilized rather vaguely to any roof using a steeply pitched major slope. In the case of a mansard loft conversion, a steeply-pitched lower slope is applied to the rear elevation and sometimes to the front as well.
Where it is applied to an urban front elevation this could rise from behind a parapet wall as an edition of a butterfly roof. Since day form usually includes a flat upper slope, it is usually known as a half mansard.
The mansard is a recessive form, with the notion that should be inclined, and it is there- fore successful in lowering the obvious size of a transformed roof space. Properly detailed and correctly implemented, the mansard is most likely by far the most attractive of the styles of loft conversions. ln a variety of inner London boroughs, taking on a mansard- design slope oftentimes a planning necessity especially when facing highway elevations when terraced roofs are modified Note that an alteration of this sort is usually thought to amount to a roof extension rather than a loft conversion with the reason for planning and building control.
Mansard conversions are occasionally placed on the back elevation only, with gables or compartment walls extended upwards to form flank gables As with full-width dormers with masonry flanks above, this approach is most easily used in terraced houses in which the existing party wall parapets pro-ject above the roof slope.
With regard to appearance, the modern flank gable walls are generally raked back to match the pitch angle of the mansard. The mansard slope, that is usually inset from the masonry flanks, is generally clad with slate or tile.