Hello guys, welcome back to my blog. Have you ever seen those old buildings in Paris where the top floor looks like it is hiding inside the roof? Well that roof is called mansard roof, and today I am going to tell you everything about it.
In this blog I will cover what is mansard roof, its parts, where it come from, its types and the materials people use on it. I will also share the pros and cons, the cost and some real talk from homeowners and roofers on Reddit. If you are thinking to buy a house with this roof or build one, then this blog is for you. So lets get started.
What Is Mansard Roof?
So lets start with the simple meaning. A mansard roof is a four-sided roof where every side has two slopes. The lower slope is very steep, sometimes it look almost like a wall. The upper slope is very low and many times it is almost flat, so you can not even see it from the street.
The mansard roof entry in Encyclopaedia Britannica explains it the same way, two slopes on every side and the lower one much steeper then the upper one. This roof is also called a French roof or curb roof, so do not get confused if you see these names somewhere.
The real magic is in that steep lower slope. Because it goes up almost straight, you get a full room inside the roof instead of a small dark attic. Most mansard roofs also have dormer windows sticking out from the lower slope to bring light inside. I think this is the smartest thing about this roof, you get one extra floor but the house do not look too tall.
Here is a quick look at mansard roof in one table.
| Feature | Details |
|---|---|
| Other names | French roof, curb roof |
| Number of sides | 4 |
| Slopes on each side | 2 (steep lower slope, low upper slope) |
| Named after | French architect François Mansart (1598–1666) |
| Early example | Louvre in Paris, around 1550 (by Pierre Lescot) |
| Most famous style | Second Empire, popular in the mid-1800s |
| Space inside | An attic room, often called a garret |
| Common materials | Slate, metal, asphalt shingles, cedar shakes |
Parts of a Mansard Roof
Before we go deep, I think you should know the main parts of this roof. It will help you a lot when you talk with a roofer or a home inspector.
| Part | What it is |
|---|---|
| Lower slope | The very steep side of the roof. It is almost like a wall, and the top floor rooms are behind it. |
| Upper slope (top deck) | The low part on top. Many times it is almost flat. |
| Curb | The line where the steep slope meets the low slope. A heavy wooden beam sits under it. |
| Dormer windows | Small windows that stick out of the steep slope to bring light inside. |
| Cornice | The fancy edge at the bottom of the roof, often with wooden brackets. |
| Cresting | Decorative iron trim on the top edge, mostly on old Victorian houses. |
Dormers are a big part of the look. Britannica’s article on dormer windows says the word comes from a Latin word for sleeping room, and these windows usually give light to a bedroom. I find this fact very cute, because in a mansard house the top floor is mostly bedrooms only.
On old Victorian houses you will also see patterned shingles, a bracketed cornice and an iron crest on the roof. The Pennsylvania Architectural Field Guide page on Second Empire style lists all of these as common features of this style. Honestly, when I see a house with all these details, it look like a big wedding cake to me.
The upper part is low or flat, so roofers usually treat it like a flat roof. The steep part and the flat part need different materials, and this is a very important point. I will explain it more in the materials section below.
History of Mansard Roof (Where It Come From?)
I really love the history part of this roof, because it has a lot of twists. Let me tell you the story step by step.
It Started in Paris
One of the first known examples is on the Lescot Wing of the Louvre, which architect Pierre Lescot built between 1546 and 1551. So the roof is actually older then the man it is named after.
The name comes from French architect François Mansart, who was born in Paris in 1598 and died in 1666. He did not invent this roof, but he used it so much on his buildings that people started calling it by his name. If you ask me, that is the best marketing anyone can get.
The Tax Story Is Mostly a Myth
You will read on many websites that Mansart made this roof to save tax. I also believed it before. But the popular window tax story is mostly a myth, because the French window tax only came in 1798. That is 132 years after Mansart died, and it did not even exempt mansard windows.
The real reason is more boring but more true. From 1783, Paris had a rule that buildings could only be 20 metres (about 65 feet) tall, and this height was measured only up to the cornice. So the rooms inside a mansard roof did not count. Later in 1902 the rule changed and people could build three or even four floors inside such a roof. Smart, no?
Funny thing is, the same trick was used in the Soviet Union also. Until 1981, a dacha (country house) was allowed only one storey, but the space inside a mansard roof was counted as attic. So people used it to almost double their space.
Haussmann and the Second Empire
The roof became super popular again in the 1850s. Emperor Napoleon III asked Georges-Eugène Haussmann to rebuild the city, and Haussmann’s renovation of Paris ran from 1853 to 1870. The street plan and look of central Paris today mostly comes from this time. This French look is called Second Empire style, after Napoleon III’s empire.
Mansard Mania in America
From France, the style jumped to America. After the Civil War, Americans went crazy for it. The Old-House Journal article on the mania for mansard roofs in America says the style was even nicknamed “General Grant style”, because it was most popular during the presidency of Ulysses S. Grant (1869 to 1877). People even added mansard roofs on small one-storey houses, just to make them look rich. I can understand this, everybody want their house to look fancy.
The Great Boston Fire
But there is a dark side also. On November 9, 1872, a huge fire started in Boston. The Boston Public Library’s post on the Great Boston Fire of 1872 explains that the wooden mansard roofs in that area gave fuel to the flames, and the narrow streets helped the fire jump from building to building. The fire destroyed 776 buildings across 65 acres. After this, Boston’s fire chief John Damrell pushed hard for better building safety codes.
The 1960s and 70s Comeback
The mansard came back again in a new form. Washington State’s historic preservation office has a nice page on the modern Mansard style of 1960 to 1985, which people sometimes called “French Provincial”. Many old downtown shops got a big mansard roof on the front to look modern, and the flat roof behind it was a good place to hide the machines. Some neighborhoods also allowed only one-storey houses, and a mansard helped people sneak in a second floor.
Even McDonald’s introduced its Mansard Roof design in 1969 in Matteson, Illinois. So if you grew up eating burgers in those old McDonald’s buildings with the big sloped roof, you already know this roof very well! I think this is the best part of the story, the same roof went from French palaces to fast food restaurants.
Types of Mansard Roof
Not every mansard roof look same. The main difference is in the shape of the steep lower slope. GAF’s guide on what is a mansard roof explains four main types, and here is my simple version in a table.
| Type | Shape of the lower slope | Good to know |
|---|---|---|
| Straight | Flat and almost vertical | The top slope is often not visible from the street |
| Convex | Bulges outward, a bit like a bell | Gives you the most space inside |
| Concave | Curves inward | Looks very elegant but gives a little less space |
| S-shaped | Curves in at the top, then out at the bottom | Most unique look, less space up top but more down below |
In America, the old Second Empire houses used all of these shapes. The Wikipedia page on Second Empire architecture in the United States and Canada also mentions steep, concave, convex and S-shaped mansard profiles, often with fancy iron cresting on the top edge.
There is one more type I see a lot, the fake mansard. It is just a sloped wall in front of a flat roof, mostly on shops and offices, and there is no real room behind it. If you ask me, the concave one is the most beautiful, it look like a soft wave on the house. But if you want maximum room space, go for straight or convex.
Mansard Roof vs Gambrel Roof vs Hip Roof
People mix up these three roofs a lot, and honestly I was also confused in the beginning. So let me make it simple for you.
A gambrel roof, as Wikipedia explains it, is the barn style roof with two slopes on each side, but only on two sides. The other two ends are flat triangle walls called gables. A gambrel also hangs out over the walls, while a mansard normally does not. Fun fact, the word gambrel comes from a Latin word for a horse’s leg, because the shape looks like the bend in a horse’s back leg.
Fixr’s gambrel roof guide says the lower slope of a gambrel sits at about 60 degrees and the upper one at about 30 degrees. That is why you see it so much on barns and sheds, it gives a lot of storage space on top.
A hip roof is different again. It slopes down on all four sides like a mansard, but each side has only one slope. GAF’s guide to hip roofs says hip roofs are among the most common roof types after gable roofs, and they handle strong wind very well. Interesting thing, GAF even counts the mansard as a kind of hip roof with eight roof faces instead of four.
| Feature | Mansard roof | Gambrel roof | Hip roof |
|---|---|---|---|
| Sides that slope | 4 | 2 | 4 |
| Slopes on each side | 2 | 2 | 1 |
| Gable (triangle) ends | No | Yes, two | No |
| Space under the roof | Almost a full floor | Big | Small |
| Common on | Second Empire houses, city buildings | Barns, Dutch Colonial houses | Many family houses |
| Wind and snow | Flat top is weak for snow | Medium | Very strong |
| Cost to frame | Highest | Lowest of the three | In the middle |
If you want maximum space and a classy look, mansard wins for sure. But if you live in a windy or very snowy place and want low maintenance, I think a hip roof is the smarter choice.
Best Materials for a Mansard Roof
A mansard roof is special because it has two very different parts. The steep part acts almost like a wall, and the top part acts like a flat roof. So you need the right material for each part, otherwise you will get leaks.
Slate
Slate is the classic choice, and honestly the most beautiful one. The National Park Service’s guide to repairing and maintaining historic slate roofs says a good slate roof can last 60 to 125 years or even longer. It also says colorful slate laid in patterns was very well suited to the mansard roofs of the Second Empire style. And because water runs off so fast, the steep slopes of mansard roofs often keep their original slate long after the rest of the roof is replaced. I think this is a big point in favor of slate.
Asphalt Shingles
Asphalt shingles are the cheapest option, but on a mansard they need extra care. The Asphalt Roofing Manufacturers Association has special recommendations for asphalt shingles on mansard roofs and other slopes steeper than 21:12. On such steep slopes the factory glue strip does not stick well, specially in cold or shady areas. So roofers must follow the maker’s nailing pattern and put small dabs of roof cement under the shingles, four dabs under each laminated shingle. ARMA also warns that the space behind a mansard can trap moist air, so it needs proper ventilation.
Metal (Copper, Zinc and Standing Seam)
Metal is a very good choice for the steep faces because it is light and sheds water fast. The Copper Development Association’s design details for copper mansard roofing say most copper mansards use standing seam or batten seam panels.
In Paris, many of those famous grey rooftops are covered with zinc. In December 2024 UNESCO added the skills of Paris zinc roofers to its intangible cultural heritage list, and the AP report on the Paris zinc roof restorers says almost 80 percent of the city’s roofs are covered in zinc. That is a crazy number if you ask me.
Wood and Fish Scale Shingles
Cedar shingles were also very common, specially on the 1960s and 70s mansards. On Victorian houses, people loved fancy shaped shingles like fish scale, diamond and arrow cuts. Old-House Online’s article on decorative shingle patterns on Victorian houses even shows a Second Empire mansard roof with four different shingle cuts on it. These patterns are my favorite part of old mansard houses.
The Flat Top
For the top part you usually need a flat roof membrane, because the slope is too low for shingles. This Old House’s article on what is a mansard roof suggests lightweight materials for a mansard and says to avoid heavy concrete tiles. It also says a white membrane on the top can help keep the house cooler in warm places.
| Material | Best place on the roof | Good to know |
|---|---|---|
| Slate | Steep lower slope | Can last 60 to 125+ years, heavy and costly |
| Asphalt shingles | Steep lower slope | Cheapest, but needs special nailing and hand sealing |
| Metal (copper, zinc, steel) | Steep slope and top | Light, sheds water fast, standing seam is popular |
| Cedar or fish scale shingles | Steep lower slope | Classic Victorian look, needs regular care |
| Membrane (like EPDM or TPO) | Flat top | Needed because the top is almost flat |
Pros of Mansard Roof (Why People Love It)
Now lets talk about the good side. There are some really strong reasons why this roof is still around after almost 500 years.
1. You Get Almost a Full Extra Floor
This is the biggest reason. The steep sides go up almost straight, so the top floor is not a dark attic but a real room. GAF’s article on the modern mansard roof comeback says this style can turn an attic you normally can’t use into proper living space. People are even using it on tiny homes now to get a bigger sleeping loft.
2. Lots of Light and Fresh Air
Dormer windows fit perfectly in the steep slope. More windows means more sunlight and better air flow. Personally I love a bedroom with a dormer window, it feel very cozy.
3. You Can Build Up Instead of Out
In cities where land is very costly, going up is smarter then going sideways. In England, the National Planning Policy Framework chapter on making effective use of land even tells councils to allow upward extensions, including mansard roofs, when they fit the street and the neighbors. I think this shows how practical this old roof still is.
4. Timeless Good Looks
A mansard roof never really goes out of style. The Madison Trust for Historic Preservation’s story on the mansard roof’s 400-year staying power shows it on everything from French chateaux to Gilded Age hotels and even fast food restaurants. A house with this roof always stands out in the neighborhood.
5. The Flat Top Is Useful
The low top part is a handy place for solar panels. On shops and offices, it is also used to hide the AC and other machines from the street.
Cons of Mansard Roof (The Honest Truth)
I will not lie to you guys, this roof has some real problems also. Before you fall in love with it, please read this part carefully.
1. It Costs More
The shape is complex, so it needs more material, more labor and many times scaffolding. I will give you the real numbers in the cost section below.
2. Leaks Around Dormers and Corners
All those windows, valleys and corners mean more places for water to sneak in. If the flashing is not done perfectly, you will see stains on the ceiling sooner or later.
3. Water and Snow Sit on the Flat Top
The top is almost flat, so water and snow don’t run off fast. ARMA’s bulletin on the effects of ponding water on low-slope roofs says water that sits on a roof for 48 hours or more can bend the deck, damage the membrane with ice and even grow algae. It recommends a slope of at least a quarter inch per foot so the roof can drain.
In cold places you also get ice dams, where melted snow freezes at the edge and pushes water back under the roof. The University of Minnesota Extension has a helpful page on protecting your home from rain and ice dams. If you live in a snowy area, please read it before buying a mansard house.
4. Hard to Work On
Roofers can not stand on the steep part, so every repair needs ladders, planks or scaffolding. Also, not every roofer has experience with mansards, so finding a good one can take time.
5. Planning Rules Can Be Strict
In some places you need special permission, specially in historic areas. For example, London’s Tower Hamlets council has design guidelines for mansard roof extensions for only five conservation areas. It also says it has often discouraged mansard extensions in such areas because they can change the historic look of the street.
Here is a quick summary of the pros and cons in one table.
| Pros | Cons |
|---|---|
| Almost a full extra floor | Costs more to build and replace |
| More light from dormer windows | More chances of leaks at dormers and corners |
| Build up, not out | Flat top holds water and snow |
| Classic look that never gets old | Hard and risky to repair |
| Flat top can hold solar panels | Planning rules in historic areas |
What Reddit Homeowners and Roofers Say
I always like to check Reddit before writing about any house topic, because there you get real talk from real people, not sales talk. Here is what I found about mansard roofs.
A Homeowner Asking Before Buying
A homeowner on r/homeowners asked about the pros and cons of a mansard roof because he and his wife were looking at a second home with this roof. That is exactly the question many of you have, so this thread is worth a read.
“Notorious for Leaking”
One reply in that thread simply said mansards are notorious for leaking. Short and direct! Honestly this matches what the roofing experts say also, the dormers and the flat top are the weak points.
Roofers Say Labor Costs More
Over on r/Roofing, a roofer explained why mansard labor costs are higher. He said these roofs are tough to work on, and the crew needs either scaffolding or a ladder and plank setup, and both add labor to the bill.
Six Nails and Hand Sealing
Another roofer in the same discussion said each shingle needs six nails and hand sealing, with the nails going through the common bond area. This is the same idea the asphalt roofing association recommends, which I explained in the materials section. So if a roofer says the normal installation is fine on your mansard, I would get a second opinion.
One Homeowner Switched to Metal
In another r/Roofing thread, a commenter shared their mansard fix. The original shingles were probably fish scale bitumen or cedar shake, then they went with standing seam metal and had no more issues after about ten years. I really like this story, because it shows a good long-term fix.
| What Reddit users said | My take |
|---|---|
| Mansards are notorious for leaking | True when flashing and dormers are not done well |
| Labor costs more, needs scaffolding | Get at least three quotes before you decide |
| Six nails and hand sealing per shingle | Ask your roofer how they handle steep slopes |
| Standing seam metal worked for 10 years | A great option if your budget allows |
How Much Does a Mansard Roof Cost?
Now the question everybody asks me, how much money? I will be honest with you, it is not cheap.
Angi’s guide on mansard roof design, pros, cons and cost says a mansard roof replacement costs around $30,000 on average. It can go anywhere from $10,000 to $60,000 or more, depending on the size, the design and the material. Metal or tile costs more then asphalt shingles, and S-shaped roofs and extra dormers also push the price up.
For new framing, Fixr’s article all about mansard roofs says framing a mansard costs $14 to $31 per square foot, which is about 71 to 75 percent more then a simple gable roof. It also says replacing an average-size mansard costs $2,640 to $4,914 more in labor than a gable roof, because scaffolding is always needed and every shingle must be hand sealed.
| Roof style | Average cost to frame (per sq ft) |
|---|---|
| Mansard | $14 to $31 |
| Hip | $11 to $24 |
| Gambrel | $10 to $21 |
| Gable | $8 to $18 |
| Flat | $5 to $11 |
Fixr also says putting a mansard on a new house costs $9,775 to $22,236 more then a normal gable roof. And if you want to add a mansard only for extra space, compare it with a normal ground-level addition, which Fixr puts at $100 to $300 per square foot. Sometimes building on the ground is cheaper, so do the math first.
These are U.S. numbers from roofing cost guides, and real prices change a lot by city and by year. So always get local quotes from roofers who have done mansards before.
Maintenance Tips to Avoid Leaks
If you already have a mansard roof or you are buying one, these simple habits can save you a lot of money. Most of these tips come from the National Park Service’s guide on roofing for historic buildings, which I found very practical even for normal homeowners.
- Inspect it at least twice a year. Also check it after every big storm. Small problems are cheap, big problems are not.
- Keep the gutters clean. Leaves and dirt fill the gutters in spring and fall, and then water backs up under the roof. Many old mansard houses have built-in gutters hidden in the cornice, so they need extra attention.
- Watch the flashing. The NPS guide says failed flashing is usually a major cause of roof damage. Ask your roofer to check it around chimneys, dormers and the curb line.
- Check the dormers and corners. Places where two roof surfaces meet, and walls like dormer sides, are the danger spots for water.
- Look in the attic after rain or snow. Damp spots or stains on the wood are an early warning. If you see water drops on the underside of the roof, that means poor ventilation.
- Don’t walk on the steep part. Many roofing materials like slate can break if you walk on them, so leave it to the pros with proper ladders.
- Keep the flat top draining. Clear the drains and scuppers so water does not sit there for days.
- Avoid quick tar patches. Caulk and tar patches are only temporary and can make proper repairs harder later.
- Hire a roofer who knows mansards. Before buying a mansard house, I would ask a roofer to inspect it, not only a general home inspector.
Honestly, I think a mansard roof is like a classic car. It looks amazing, but it needs regular love and care to keep running well.
Famous Buildings With Mansard Roofs
Want to see a mansard roof in real life? Here are some famous ones that I really like.
Château de Maisons, France
This one was built by François Mansart himself. The Château de Maisons near Paris was designed from 1630 to 1651, and it is called a prime example of French Baroque architecture. If you visit Paris, I think this is a must for any architecture lover.
Renwick Gallery, Washington, D.C.
The Smithsonian’s page on the architectural history of the Renwick Gallery says it was the first building in the U.S. built just to be an art museum. James Renwick Jr. designed it in 1859 after getting inspired by the Louvre’s newest addition in Paris, with mansard roofs, pavilions and double columns.
Eisenhower Executive Office Building, Washington, D.C.
This big building sits right next to the White House. The White House Historical Association notes that the Eisenhower Executive Office Building was commissioned by President Ulysses S. Grant and completed in 1888, in the Second Empire style with a sloping mansard roof. Today it holds offices for much of the president’s staff.
Philadelphia City Hall
Philadelphia City Hall was built in the Second Empire style from 1871 to 1901. It is the world’s largest free-standing masonry building, and those giant mansard roofs make it look even more grand.
A Painting Called The Mansard Roof
This is my favorite fun fact. In 1923 the painter Edward Hopper made a watercolor called The Mansard Roof, now in the Brooklyn Museum. According to NPR’s story on Hopper’s Gloucester houses, the museum bought it for $100, and that sale was the breakthrough of his career. The real house in Gloucester, Massachusetts is still standing today.
| Building | Location | Year | Why it is special |
|---|---|---|---|
| Lescot Wing of the Louvre | Paris, France | 1546 to 1551 | One of the earliest known mansard roofs |
| Château de Maisons | Maisons-Laffitte, France | 1630 to 1651 | Designed by François Mansart himself |
| Renwick Gallery | Washington, D.C. | Designed 1859 | First U.S. building made as an art museum |
| Eisenhower Executive Office Building | Washington, D.C. | Completed 1888 | Next door to the White House |
| Philadelphia City Hall | Philadelphia, USA | 1871 to 1901 | World’s largest free-standing masonry building |
| The Mansard Roof (painting) | Brooklyn Museum | 1923 | Edward Hopper’s big breakthrough |
FAQs About Mansard Roof
What is mansard roof in simple words?
A mansard roof is a four-sided roof with two slopes on each side. The lower slope is very steep, almost like a wall, and the upper slope is almost flat. Because of this shape, you get a full room inside the roof.
Why is it called a mansard roof?
It is named after the French architect François Mansart (1598 to 1666), who used this roof a lot. Merriam-Webster’s entry for mansard says the word comes from the French word mansarde, and its first known use in English is around 1734.
Is a mansard roof the same as a French roof?
Mostly yes. People also call it a French roof or a curb roof, so all these names point to the same idea.
How much does a mansard roof cost?
A replacement usually costs around $30,000 on average, and it can go from $10,000 to $60,000 or more depending on the size and the material.
Do mansard roofs leak a lot?
They can, specially around the dormers and on the flat top, if the flashing and drainage are not done right. Regular inspection and a good roofer can stop most of these problems.
Can you put solar panels on a mansard roof?
Yes, but mostly on the low upper part. The steep sides are not good for solar panels.
Final Words
So guys, this was all about what is mansard roof. I tried to cover its meaning, parts, history, types, materials, pros and cons, cost, maintenance tips, famous buildings and even what real people on Reddit say about it.
If you ask me, the mansard roof is one of the smartest and most beautiful roof designs ever made. It gives you almost a full extra floor and a classic look, but it needs a good budget and regular care. So if you are planning to buy or build a house with this roof, talk to an experienced roofer first.
Tell me in the comments which type of mansard roof you like the most. And keep on visiting myarchitecturesidea.com for more info like this.
More Helpful Reading
If you want to go deeper, here are some more good reads I found during my research.
- London Assembly investigation into upward extensions and mansard roofs in London
- National Park Service guide to repairing historic wooden shingle roofs
- City of Cincinnati guide to the French Second Empire style
- Buffalo Architecture and History page on Second Empire houses and mansard roofs
- Smithsonian Magazine story on the Renwick Gallery’s mansard-roofed building