French Second Empire often incorporated elements of other styles, including Eastlake porches and Italian Villa towers. An essential characteristic, however, that distinguishes French Second Empire from other styles is a mansard roof, which is a double-pitched, hip roof with a steep lower slope. Named for Louis Mansart, its French inventor, the mansard roof provides an extra floor where wasted attic space would be. Dormer windows are used to provide light to this floor. Typical houses of the style are square or rectangular in plan, constructed of brick or wood, and have symmetrical facades. Common are multicolored slate or tin-plate roofs, cast-iron roof cresting, quoins, tall first-floor windows, bay windows, projecting central bays, and bracketed cornices.

The style is named for the French Second Empire under the reign of Napoleon III. Under his leadership, Paris was transformed into a city of grand boulevards and monumental buildings that were imitated in Europe and the United States. In this country, French Second Empire first became popular in the 1860s, reaching Cincinnati about 1870. A mansard roof was essentially all that was needed to make a house French Second Empire, and the style was adaptable to houses of many types. Elaborate mansions, urban row houses, and simple cottages are found in both working class and affluent neighborhoods in most parts of the city.