Converting the unused and often-overlooked loft in your home could provide you with enough extra space for a study, a play-room for the children, or even a new bedroom and cosy top-floor en-suite. But before you start to imagine all the things you’ll decorate your new home addition with, you first need to decide on which type of loft conversion is right for you. In this post, we discuss dormer vs Mansard loft conversions and the key differences.
What’s a Mansard conversion?
Named after a French Architect known as Francois Mansard, the Mansard loft conversion is usually built to the rear of your property, with a central flat roof, and an end-of-roof angle of 72 degrees. Most commonly found in London, these stylish extensions offer considerable increases in loft space, with the added beauty of Juliette balconies or large Velux windows.
What about a dormer?
A dormer conversion is an extension of your room beyond standard roof limitations. Like the Mansard, they’re generally built towards the rear of the property, but they come with the added benefit of often skipping the need for planning permission. Dormers can also protrude from the property, creating even more space.
We recently discussed the benefits of dormer conversions in built-up, compact cities, like London. You can find out more here.
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Dormer vs Mansard: The key differences
Depending on the size of your space, the complexity of the conversion, and the extend of post-construction installs like white-goods, transforming your loft can cost anywhere from £25,000 – £50,000 or more, so making sure you’ve chosen the right conversion for you is an all-important first step.
There are a few things to consider when planning your conversion, so we’ve broken down some of the key differences between the two types to help you understand which one fits your home and needs.
1. Where you live
Depending on where you live, you could see some benefits or restrictions to both types of conversion. The most important factor here is planning permission.
While dormers tend to stand out a little bit more, they can often skip the need for planning permission, where Mansards will nearly always require it. And, even if you’re happy with a planning application, in cities like London, you might face restrictions on the type of conversion you’re allowed to undertake.
2. The type of roof
Whether it’s for aesthetic reasons, more space, or – like your location – for planning restrictions, there are a number of differences that set these two conversion types apart.
Dormer conversions with a protruding extension tend to stand out a little bit more from street level, and as they heavily rely on the slope of your existing roof on one side, can offer less overall space. Mansard conversions offer much more in terms of head-height space, and they can look a lot sleeker from the ground, but they require planning permission.
3. How you want to use your loft
If you’re converting your loft, you’re most likely going to want as much space as possible. When it comes to usable square footage, the Mansard is going to win here.
Generally, you’ll find more area above head height with a Mansard conversion, but if you’re looking to convert on a budget, a dormer still offers plenty of space for a bedroom, and maybe even an en-suite, at a slightly lower cost. Plus, if you extend the dormer with a protruding window, you can flood the room with light while expanding your room.
4. Your budget
As is the case with any home improvement project, cost plays a big part in the decision making process.
The cost of a conversion can vary depending on a whole range of factors, from job complexity to the small, post-conversion details like fittings. When comparing Mansard and dormers, you’ll often find a dormer conversion to be slightly less expensive than a Mansard. Dormers usually start at around £45,000, while a Mansard is roughly £50,000. You can find out more about the costs of conversion here.
Guiding you every step of the way
While we hope to have answered some of the questions you might have surrounding the differences, benefits, and downsides with dormer and Mansard conversions, we know that you’ll probably have more. But don’t panic, we’ll be able to help you through the entire process, providing you with clear and precise information on how you can transform your loft, and make the most of your unused space.
Our initial visit and quotes are free. If you’re ready to start planning your next home improvement project, contact us today. Let’s create the space you’ve been dreaming of.
Related post: Pros and Cons of Different Loft Conversions
What is a Mansard Loft Conversion Really Like in Practice?
A Mansard loft conversion is more than just an upgrade to your roof. It transforms how your home looks, feels and functions. Unlike other types of loft conversion, a Mansard changes the entire shape of your roof structure, creating a near-vertical wall at the rear and a horizontal roof on top. The result is a much larger, more open internal space that feels like a proper new floor rather than just an attic room.
The design is especially suited to terraced houses and period homes found throughout London and other busy cities. If your property has a sloped roof at the back, a rear Mansard loft conversion can help you unlock maximum space. While it will require planning permission, the payoff is usually worth it in terms of increased living space and property value.
How Much Does a Mansard Loft Conversion Cost?
A typical mansard loft conversion cost starts at around £50,000, though this figure can change based on the size of your property, the complexity of the build, and the finish you choose. Things like plumbing, insulation, skylights, staircases and roof windows can all affect the final price.
While the cost might be higher than a dormer loft conversion, the extra space you gain with a Mansard makes it a worthwhile investment. You’re not just paying for an attic room, you’re adding a whole new level to your house. That could mean a large double bedroom, a home office, or even multiple rooms with a bathroom.
If you’re considering a double Mansard loft conversion, the cost will naturally be higher. But this option gives you the opportunity to reshape both the front and rear slopes of the roof, offering symmetrical design and even more square footage.
Benefits of a Mansard Conversion for Growing Families
One of the main reasons homeowners choose a Mansard loft conversion is because they need more space but don’t want to move. If you love your home, your street, and your local area, it makes sense to stay put and simply extend upwards.
A Mansard loft is ideal for families that are expanding or need separate living areas. Whether it’s a new master bedroom, a teenage retreat, or a playroom that keeps the clutter out of the main living space, this type of loft extension gives you the flexibility to plan your home around your life.
You also get better head height and more usable floor space compared to small dormers. So if you’re after something that feels like a true extension and not just a conversion, a Mansard is often the better choice.
Does a Mansard Loft Conversion Need Planning Permission?
In most cases, yes. A Mansard conversion changes the shape of the roof significantly, so it usually falls outside permitted development rights. That means you’ll need full planning permission for a Mansard.
While this might sound like a barrier, it’s something we help you manage from day one. At SimplyEasy Refurbs, we take care of the drawings, the paperwork, and all the communication with your local authority. Once planning is approved, we also make sure your project meets all current building regulations. These cover things like fire safety, insulation, access, and structural support.
Even if the process takes a bit more time, it ensures that your loft conversion is safe, legal, and built to last.
What is the Difference Between a Mansard Roof and Other Roof Types?
A standard pitched roof slopes on both sides and often creates a triangle shape that limits head height inside the loft. A dormer loft conversion works within this existing roof slope by building a box-shaped dormer that sticks out, offering some extra space and light.
A Mansard roof, however, reshapes the rear slope into a near-vertical wall with windows or doors. This allows for maximum internal space and clean lines from the street. Some homeowners even opt for a mansard roof extension with Juliet balconies or a small roof terrace, depending on their layout and planning approval.
Compared to a dormer, the Mansard gives you more consistent ceiling height, better insulation options, and a sleek external look.
Mansard Loft Conversion Ideas That Maximise Space
If you’re unsure what to do with all that new space, there are plenty of mansard loft conversion ideas to consider. Many homeowners choose to add a full-sized bedroom with built-in wardrobes and storage. Others go for a home office with a view, especially since remote work is now more common.
A popular choice is turning the loft into a luxury master suite, complete with en-suite bathroom, Velux windows, and clever lighting. Some even use their extra living space for a studio, a guest suite, or a quiet reading nook tucked under the flat roof.
If you’ve got a semi detached home with enough room at the front and back, a double Mansard loft conversion could give you space for multiple rooms, including a bathroom and landing. With the right design, your new loft level could feel like it was always part of the home.
Choosing the Right Loft Conversion Specialist
A Mansard conversion involves extensive structural work, so choosing the right loft conversion specialist is crucial. You’ll want a team that understands local planning policies, knows how to work with older buildings, and can guide you through everything from drawings to handover.
At SimplyEasy Refurbs, we don’t just build lofts. We support you at every step. We’ll walk you through your options, explain your loft conversion project in plain English, and handle the heavy lifting with your local council.
We also know how to make the most of existing roof shapes, ensuring your new loft space is safe, stylish, and functional. And if you’re wondering whether your roof structure is suitable for a Mansard extension, our team can carry out a free site visit and tell you exactly what’s possible.
Is a Mansard Loft Right for You?
If you’re after more than just a room with a sloped ceiling, and you want a proper floor with full-height walls and lots of light, a Mansard loft could be perfect for you. It offers the biggest return in terms of usable space, flexibility, and value.
Yes, you’ll need planning permission for a Mansard. And yes, the initial loft conversion cost may be higher. But the results speak for themselves. Whether it’s a stylish master suite, an extra bedroom for the kids, or a calm work-from-home zone, a Mansard gives you more space to live the way you want.
