The mansard or mansard roof (also known a curb roof or French roof) is a four sided gambrel-design hip roof defined by two slopes on every one of its own sides with the lower pitch, punctured by dormer windows, at a steeper angle compared to the upper. The steep roof with windows creates an extra floor of habitable space, (a garret), and reduces the total height of the roof for a specified number of habitable stories. When viewed from close proximity to the building the top slope of the roof might not be visible from ground level.
The first known example of a mansard roof is credited to Pierre Lescot on section of the Louvre constructed around 1550. Francois Mansart (1598-1666), an accomplished architect of the French Baroque period, popularized this roof layout in the early 17th century. It became particularly hip during the Second French Empire (1852-1870) of Napoleon III. Mansard in Europe also means the loft (garret) space itself, not merely the roof contour and is frequently used in Europe to mean a gambrel roof.
The characteristics of mansard roof
Two different characteristics of the mansard roof – a double pitch as well as steep sides – occasionally lead to it being mistaken for other types of roofs. Since the upper pitch of a mansard roof is barely observable from the ground, a standard single-plane roof with steep sides could be mistaken for a mansard roof. The gambrel roof design, usually seen in barns in North America, is a close cousin of the mansard. Both mansard and gambrel roofs fall under the general classification of “curb roofs” (a pitched roof that slopes away from the ridge in two consecutive planes). However, the mansard is a curb hip roof, with gradients on all sides of the building, and the gambrel is a curb gable roof, with pitches on just two sides. (The curb is simply a horizontal plank right below where the two roof surfaces join.) The French roof is frequently used synonymously with the mansard but it is additionally defined as an American version of a mansard with the lower pitches bigger and almost perpendicular in proportion to the top pitches.
A major difference between the two, for water drainage and snow loading, is that, when seen from above, Gambrel roofs end in a long, sharp point in the principal roof beam, while mansard roofs always form a roof that is low-pitched.
In Germany and France, no differentiation is made between mansards and gambrels – they’re both called “mansards.” In French, mansarde can be a term for the garret living space, or loft, right within it, or for the type of roof.
The mansard style ensures maximum utilization of the interior space of the loft and provides an easy way to add one or more stories to an existing (or new) building without always requiring any masonry. In many instances, the decorative potential of the Mansard is exploited using concave or convex curvature and using elegant dormer window surrounds.
Since they allowed usable living quarters to be put in the loft, mansard roofs were considered particularly practical. Because this, old buildings were frequently remodeled using mansard roofs.
Currently, mansard style roofs are used for one- and two-story apartment buildings, Neo-eclectic houses, and restaurants.