What is a mansard roof? What it looks like, why Paris and Second Empire America are full of them, the tax story, the pros and cons, and how to spot one

Architecture · 4 September 2026

A mansard roof has two slopes on each of its four sides, a lower slope so steep it is almost a wall, usually with dormer windows in it, and an upper slope so shallow it is almost flat and cannot be seen from the street, so that the space under the roof is a full storey with headroom, the attic becoming an apartment; it is named for the French architect François Mansart, who made it fashionable on Paris houses in the 1630s, though it existed before him, on the Louvre of 1550. It was revived in the Paris of Napoleon III and Haussmann in the 1850s, where it gave the apartment house an extra storey above the height the building code allowed, and crossed to the United States as the mark of the Second Empire style of 1855 to 1885, on courthouses, city halls, mansions and the small-town houses that Hollywood has used for haunted ones ever since. Below: the shape, the name, the Paris history, the American style, the difference from a gambrel, the details, the modern mansard, the pros and cons, and the tax story, with the Louvre in the Buildings by style collection and the style in Victorian architecture and American house styles.

The shape

A roof with one slope on each side is a hip roof; a mansard has two, and the lower one is steep, from 60 to almost 90 degrees, and the upper one shallow, 10 to 30 degrees, meeting at a curb or angle that from the street is the top edge of the building. The lower slope is the wall of the top floor, covered in slate, tile, shingles or metal rather than brick, and pierced by dormer windows, the upper slope the roof proper, often flat enough to walk on and hidden behind the curb; the lower slope may be straight, concave, convex or S-shaped, each a variant with a name, the concave "bell-cast" being French and the convex the Second Empire favourite. A mansard on all four sides is the true form; a "mansard" on two sides with gables at the ends is a gambrel, the roof of the Dutch barn. The attic under a mansard is the "mansard" in French, and the word means the room as much as the roof. Mansard roof.

Mansart, the Louvre and Paris

The double-pitched roof appears on the Louvre's Lescot wing of about 1550, by Pierre Lescot, and on 16th-century French châteaux, but it was François Mansart (1598–1666), the architect of the Château de Maisons and the Val-de-Grâce, who used it so consistently on his Paris hôtels that the roof took his name, spelled mansarde in French with an e and mansard in English; his great-nephew Jules Hardouin-Mansart, the architect of Versailles, spread it further. In the 17th and 18th centuries it was the roof of the Paris town house, and in the 1850s and 60s Baron Haussmann's rebuilding of Paris for Napoleon III made it universal: the building code fixed the height of the cornice on a street by the street's width, about 20 m on the boulevards, and allowed a roof above it of a set slope, and a mansard put a whole floor of rooms, and then two, above the cornice inside the permitted roof, the chambres de bonne, the maids' rooms under the slates with their round oeil-de-boeuf windows, which are now the studio flats of Paris. The Louvre's Napoleon III wings of the 1850s, the Gare du Nord, the Opéra and the boulevards are lined with mansards, and it is the skyline of Paris, the grey zinc and slate roofs with their chimneys that every painting of the city shows.

Second Empire America, 1855–1885

The Paris of Napoleon III was the model of the modern city, and after the Paris exhibitions of 1855 and 1867 American architects took the mansard as the newest thing: the Second Empire style, of a symmetrical block with a mansard roof, often a central tower with its own mansard, dormers, iron cresting along the curb, bracketed cornices and tall windows, was the official style of the Grant administration, on the State, War and Navy Building beside the White House (1871–88), the largest office building in the world when built, Boston City Hall (1865), Philadelphia City Hall (1871–1901), the Old Executive Office Building, and courthouses and post offices in every state, and the style of the mansions of the newly rich in the 1870s, from Newport to San Francisco, and of thousands of ordinary houses with a mansard on a square plan. Its fashion ended with the depression of 1873 and the Queen Anne of the 1880s, and by 1900 the mansard was old-fashioned, which is why the Second Empire house became the haunted house: the Addams Family's house of the 1960s show, the Bates house in Psycho (1960), built on the Universal lot from a Second Empire model, and the mansion of every horror film since are mansard-roofed, the roof reading to Americans as gloomy, old and French.

Mansard, gambrel, hip, and the details

• Gambrel. Two slopes on two sides with gables at the ends, the roof of the Dutch Colonial house and the American barn; a mansard has four sides.
• Hip. One slope on each of four sides; a mansard is a hip roof with the lower part steepened.
• Dormers. Every mansard has them, in the lower slope, with arched, pedimented or round heads; without them the attic is dark.
• Cladding. Slate, laid in patterns of colour and fish-scale shapes on American mansards; zinc in Paris; tin and shingle in the country.
• Cresting. Iron railing along the curb between the slopes, a Second Empire flourish, mostly gone.
• Curb. The angle between the slopes, often with a moulding.
• Tower. A central or corner tower with its own steeper mansard and a bulbous or concave roof, the sign of the grander Second Empire house.

The modern mansard

The mansard came back in the 1960s and 70s as the "mansard" of the American suburb, a steep sloped band of shingles around the top of a one-storey shop, bank or fast-food restaurant hiding the flat roof and the air-conditioning, on McDonald's from 1969, Pizza Hut and every strip mall of the decade, a fake mansard with no floor behind it, which architects mocked and which is now a period piece. In cities the mansard is the standard way to add a storey to an old building within height rules, as in Paris still, and in London and New York the "mansard extension" of a terrace house is a planning fight; in the 2000s and 2010s new apartment blocks in Paris, London and Boston were given mansards to fit the street, and the roof has a second life as a zoning device, which is what it was in 1860.

Pros and cons

• For. A whole extra floor of usable space within the height of a roof, with windows; a fashionable and handsome shape; easy to extend upward later by raising the curb.
• Against. The shallow top slope drains badly and needs a good membrane, and is the source of leaks in old houses; the slate lower slope is expensive to repair; snow sits on the flat top; the dormers are cold and the attic hot; and, in Paris, the top floor was for servants for a reason.

Versions and theories

• The tax story. The mansard is said to have been invented to dodge a French tax on the number of storeys below the roof, or a Paris tax on height, the attic not counting; there was no such tax on storeys, and the true story is the Paris height limit, measured to the cornice, under which the mansard added floors legally. In America the same story is told of a tax on "full" storeys, and is equally unfounded.
• Mansart invented it. He popularised it; the Louvre of 1550 had it first.
• Mansard and Mansart. The architect is Mansart with a t; the roof is mansard in English and mansarde in French.
• Second Empire is Victorian. In America the Second Empire is one of the Victorian styles, of the 1860s and 70s, alongside Italianate before it and Queen Anne after; in Britain it barely appears.
• The Bates house is a real house. It is a set on the Universal lot, built in 1959 and moved several times, modelled on Edward Hopper's painting "House by the Railroad" of 1925, of a Second Empire house in Haverstraw, New York, which is real.

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