A mansard or mansard roof (also called a French roof or curb roof) is a four-sided gambrel-style hip roof characterized by two slopes on each of its sides with the lower slope, punctured by dormer windows, at a steeper angle than the upper. The steep roof with windows creates an additional floor of habitable space, (a garret), and reduces the overall height of the roof for a given number of habitable storeys. The upper slope of the roof may not be visible from street level when viewed from close proximity to the building.