Mansart

The mansard roof -- a roof with two slopes on each side, the lower slope steeper than the upper -- takes its name from Francois Mansart (1598-1666), one of the most influential architects of the French Baroque period. Mansart did not invent the double-sloped roof form; examples exist in French architecture from the sixteenth century, and the basic principle was known to medieval builders. What Mansart did was integrate the form into a coherent architectural language, using it so consistently and so elegantly in his designs for chateaux and townhouses that his contemporaries began calling it the mansarde. The architect's name became inseparable from the roof profile he championed, a rare case of an architectural feature being permanently branded by its most famous practitioner rather than its actual inventor.

The mansard roof solved a practical problem with characteristic French ingenuity. Under Parisian building regulations of the seventeenth century, building height was measured to the cornice line -- the point where the wall met the roof. Space within the roof itself was not counted as a full story. The steep lower slope of the mansard roof created usable living space that technically existed within the roof, allowing builders to add an extra floor without violating height restrictions. Tax assessors measured floor area at the cornice; the mansard provided floor area above it. The roof was, in effect, a legal loophole rendered in slate and timber, and it made the architect's name synonymous with Parisian architectural cleverness.

Baron Haussmann's massive renovation of Paris in the 1850s and 1860s made the mansard roof the defining feature of the Parisian streetscape. Haussmann mandated uniform building heights and facade treatments, and the mansard became the standard roof form for the thousands of apartment buildings constructed during his transformation of the city. The silvery zinc-clad mansard roofs, punctuated by rows of dormer windows, gave Paris its characteristic skyline -- that distinctive silhouette of angled rooflines against gray skies that remains the city's visual signature today. A single architect's surname became the name of an entire city's architectural identity.

The mansard crossed the Atlantic during the Second Empire period (1852-1870), when French taste dominated American architecture. Mansard-roofed buildings appeared across the United States, from public buildings and railway stations to private homes. The style became so popular in America during the 1860s and 1870s that it earned its own designation: Second Empire style. Though the fashion eventually waned, mansard roofs remain common in American Victorian neighborhoods and in the visual vocabulary of traditional architecture. Francois Mansart, who died in 1666 without ever visiting the Americas, left his name on buildings he could never have imagined, in cities that did not yet exist when he drew his first roof.