What is a Mansard Roof?

A mansard roof is one of the most unique roof styles you’ll find on homes. It gives a home the Tudor or cottage look that sticks out among common roofs in the neighborhood. 

However, this uniqueness also means major differences compared to a hip or gable roof. So, what exactly is a mansard roof, and what do you need to know about it?

For over 30 years, the team at Bill Ragan Roofing has helped homeowners understand the complexities of the roofing industry. That’s why I’ll break down a mansard roof and what makes it unique compared to other roof styles. 

This article answers the following questions:

• What is a mansard roof?
• What are the types of mansard roofs?
• What’s the right roofing material for a mansard roof?
• Does the top portion of a mansard roof require a different roofing material?
• Why is a mansard roof replacement so expensive?

What is a mansard roof?

A mansard roof (also called a French or curb roof) is a double-sloped roof with a vertical, steep pitch on the sides and a flat or low slope roof section on top. Depending on the home, the top story will have the lower section of the roof (on two or all four sides) around it. 

Think of it as the outer walls of your home but with a roof instead of brick or siding. While a mansard roof isn’t 100% vertical, it usually has the steepest pitch a roof can have.

It still needs to come out about two feet from the bottom, then slant up to the ridge to create enough of an angle for water to drain. 

What are the types of mansard roofs?

“Mansard” is the general term for this specific roof style, like a hip or gable roof. However, there are different types of mansard roofs depending on the architectural design of the lower portion (outer walls).

• Straight: The most basic type with an almost vertical lower slope in a straight line and a low-pitched roof on top. 
  
  
• Convex: Unlike a straight mansard roof, the convex style has a lower slope that curves outward like a bell. 
  
  
• Concave: This style of mansard roof is the opposite of convex, with the lower slope curving inward. 
  
  
• S-shape: An s-shape mansard roof’s lower slope is a mix of the convex and concave style roofs. It starts with an inward curve at the top before curving outward as it goes down to the roof line.

What’s the right roofing material for a mansard roof?

Because a mansard roof has such a steep pitch, only certain roofing materials can be installed because of weight. While you can technically use asphalt shingles, I don’t recommend them.

This is mainly due to the weight of shingles and the likelihood of them sliding off if they’re not properly installed. That’s why I recommend synthetic shingles or cedar shake shingles for a mansard roof replacement. 

(Synthetic slate shingles installed on a mansard roof)

Synthetic shingles are a premium roof material made out of an engineered polymer or recycled materials that mimic the look of slate or cedar shake shingles. They’ll be more expensive than asphalt shingles, but they last longer and won’t slide off because they’re lightweight.  

Cedar shake shingles are also a premium material made of natural wood (cedar) materials that are much lighter than asphalt shingles. Like the synthetic shingles, they’ll be much more expensive than asphalt shingles. 

Ultimately, it’ll be up to your budget and the look you want when deciding what shingle to put on your mansard roof. And if you’re adamant about asphalt shingles, make sure to invest in a luxury shingle. 

Does the top portion of a mansard roof require a different roofing material?

Like the mansard roof’s vertical sides need a specific roofing material, so does the top portion. If it’s above a 2:12 pitch (2 vertical units up for every 12 horizontal units out), you should be able to use the same material as you did for the lower part. 

However, anything below a 2:12 pitch or even completely flat requires a water-tight membrane to handle sitting water. Because of this, a mansard roof with a low slope or flat roof pitch on top needs a membrane roof system like EPDM, PVC, or TPO. 

(EPDM on low slope portion of a mansard roof)

You can’t see this portion of the roof, so you’ll need to pick the membrane based on what you want. TPO and PVC usually come in white (or other light colors) and are reflective, which makes it easier to keep the rooms below cooler. 

EPDM is a black rubber membrane that is durable and extremely hard to penetrate. While it’s a slight exaggeration, I like to say it’s a “bulletproof” roof system. 

You can’t go wrong with any membrane roof system, so just pick the one with the functionality you want out of it. 

Why is a mansard roof replacement so expensive?

If you have a mansard roof, be prepared for a very pricey roof replacement. The reason it’s so expensive comes down to the labor, time, and materials required to do it properly. 

(Mansard roof torn off before installation)

The lower portion’s steep pitch means a mansard roof can’t be walked on, so the crew must stand on ladders for the tear-off and installation processes. Not only does this mean moving slower, but the complexity of the process also increases labor costs. 

Then, you have the high material costs from choosing a premium roof system (if you take my recommendation), plus the other roofing components and the membrane roof system (if applicable) for the top portion. All this together makes a mansard roof replacement slow, expensive, and complex. 

How do you find a high-quality roofer for your mansard roof replacement?

Now you know what a mansard roof is and what you need to know about it. At the end of the day, a mansard roof is unique compared to standard roof styles. 

It requires expertise to do correctly, especially ensuring the right materials are installed to ensure you get the most out of your investment. That’s why you need to ask any potential roofing contractor if they’ve worked on mansard roofs in the past. 

But that’s not the only thing you need to look for to ensure you get the best quality roof replacement possible. That’s why I wrote another article with the tips needed to find a great roofer in your area. 

Check out 7 Tips to Find a Great Roofing Contractor to make the best hiring decision for your mansard roof replacement.