What are the benefits of a mansard loft conversion?

This loft type is one of the most effective ways to gain usable headroom and extra living space, whether that’s for a bedroom, bathroom, office, play area or something different. Offers more usable space than other loft types. Blends well with period architecture. Often preferred by planning officers in London and the Home Counties over rear dormer conversions.

How much does a Mansard Loft Conversion Cost?

The cost of a Mansard loft conversion is approximately £40,000 – £80,000+ depending on your location, the full requirements of the project and the specification and finishes desired. For a free, personalised quote, get in touch with our specialist team.

What is the difference between a Mansard and Rear Dormer Loft Conversion?

A rear dormer loft conversion keeps most of your existing roof structure and simply extends the back slope outward to add more headroom and space. It’s usually cheaper, quicker, and can be less disruptive. A Mansard loft conversion is a bigger structural change that alters the entire roof profile, essentially creating a full extra story of your home with better height and more room overall. Because of this, Mansards tend to offer the most space and design flexibility but often cost more and usually require planning permission, whereas rear dormers sometimes fall under permitted development.

What is the difference between a Mansard and Velux Loft Conversion?

A Velux conversion keeps the existing roof shape and adds roof windows, making it the least disruptive option. A Mansard conversion, on the other hand, involves significant structural changes to maximise space and headroom.

Mansard Loft Conversion | The Loft Room

What is a mansard loft conversion?

A Mansard loft conversion is a type of extension that changes the shape of your roof for maximum internal space for a far larger usable living space. It involves altering the slope of one side of the roof to create a flat roof, with a slight downward pitch for drainage, and an almost vertical 72 degree inward-sloping wall where the windows are housed in small dormers.

The Mansard conversion is typically built at the rear of the property but can sometimes be added to the front, subject to local planning policies and neighbouring precedents, and is a popular choice for period properties and loft conversions in cities like London.

This Mansard roof design is named after 17th-century French architect François Mansard and is known for its elegant, space-enhancing structure.

Key Features of a Mansard roof

Most popular on period properties and homes in urban areas.
Ideal for semi-detached and terraced houses, especially where space is limited.
Maximises space in character lofts while maintaining their architectural style
If your property has Permitted Development rights, you can build under a Certificate of Lawfulness. If not, planning permission will be required.

Other Types of Mansard Loft Conversions

L-shaped Mansard loft conversion
Double Mansard loft conversion
Mansard loft conversion with Dormer
Mansard loft conversion with roof terrace

There are various other loft types available so we’d always recommend looking over our full range of options or contacting our team to discuss the most suitable type of loft conversion for your property.

Benefits of a mansard loft conversion

This loft type is one of the most effective ways to gain usable headroom and extra living space, whether that’s for a bedroom, bathroom, office, play area or something different.

Offers more usable space than other loft types.
Blends well with period architecture.
Often preferred by planning officers in London and the Home Counties over rear dormer conversions.

To better understand the pros and cons of a Mansard Loft Conversion, check out our blog.

      EXCELLENT  
   Based on 407 reviews 
    
 
 
 
   
 
 
      Posted on Google  
   
   Sarah-Jane Westlake 
 28 October 2026
 
 
 Trustindex verifies that the original source of the review is Google. Eddie, our main contractor, and his labourer Damian were an absolute joy to have on-site. Their professionalism, manners, and attention to detail were exceptional. Eddie’s workmanship is top-tier, and the speed and efficiency with which he executed the project were incredibly impressive. We absolutely love our new loft space, and the sheer quality of the construction delivered by Eddie and his brilliant on-site team completely earned this top rating.
If we were judging solely on The Loft Room side, this would have been closer to a 4-star review. Communication with the head office was sometimes a little haphazard, and there were some unexpected plumbing extras from early bathroom decisions that could have been made clearer by sharing an indicative plumbing "extras" cost upfront. We also received some inaccurate guidance from The Loft Room on paint quantities for the new bedroom and en-suite, which left us with far too much paint that couldn't be returned and the "free" decoration incentive was disappointing due to a poor finish and surly decorators.
Ultimately, though, a build is only as good as the person executing it. Eddie’s fantastic management, swift pace, and flawless execution completely outshone other frustrations. We couldn't be happier with the final result.
  
 
     Posted on Google  
   
   Sam Kemp 
 21 October 2026
 
 
 Trustindex verifies that the original source of the review is Google. Dragos and his team did a great job for us. They provided a complete end to end service from design, architecture and planning permission, full loft construction and decorating.
Early on in the project, with the support of Dragos, we decided to make a fundamental change to the design. They took this in their stride with no material change to the cost.
The team were considerate, skilled, polite and reliable throughout the project.
I would thoroughly recommend The Loft Room to anyone considering a loft extension or major alteration.
  
 
     Posted on Google  
   
   Iain Russell 
 19 October 2026
 
 
 Trustindex verifies that the original source of the review is Google. From the moment we spoke to Maggie, we felt The Loft Room was the right company for us. The whole admin team (Maggie, Melissa, Helen and Ciara) are warm and friendly, and super efficient.

Dave and Ashley (and Charlie) have done a fantastic job converting our loft. We have wholeheartedly trusted Dave’s expertise with him having completed 42 lofts previously. We are absolutely delighted with the results so far.  The tradespeople that have been over have been excellent: Mark and Kasper - the roofers, Stuart - electrician, Justin - plasterer, Dave - painter etc.

We did get some lower quotes from other companies, but we think there’s a strong case of ‘you get what you pay for’ with The Loft Room. The whole process was surprisingly smooth and unobtrusive - we just hadn’t expected that from a loft conversion. We would definitely recommend The Loft Company.
  
 
     Posted on Google  
   
   Richard Jones 
 19 October 2026
 
 
 Trustindex verifies that the original source of the review is Google. Really happy with the finished loft conversion! The team was very friendly, professional, and respectful of our home throughout the project. While it took a little longer than initially expected, we put it down to the extreme heat of the summer we just had. The quality of the final build makes it well worth it—would recommend!
  
 
     Posted on Google  
   
   Henry 
 6 October 2026
 
 
 Trustindex verifies that the original source of the review is Google. We recently had a rear dormer completed by The Loft Room, which also involved lowering the ceilings throughout the first floor.

The efficiency and quality of the work carried out are the main reasons we’ve given five stars. We felt the administrative and communications side of the process could have been better, but ultimately the most important thing for us was the quality of the build, and in that respect we were extremely happy.

The team on site were excellent and always treated the house as our home rather than simply a building site. They were respectful, tidy and a pleasure to have around throughout the project.

Dragos has been a joy to work with and brought a huge amount of calm, experience and knowledge to the project. Lulian, on site, was the ultimate professional. Nothing was ever too much trouble, and the quality of his workmanship was excellent.

Overall, we’re really pleased with the end result and wouldn’t hesitate to recommend The Loft Room based on the quality of the work and the team we had on site.
  
 
     Posted on Google  
   
   Ruth Gibbons O'Brien 
 2 October 2026
 
 
 Trustindex verifies that the original source of the review is Google. We are so happy with our new loft space and have been really impressed with The Loft Room from start to finish.

Communication throughout the project has been excellent. Marius and his team worked incredibly hard to meet deadlines while taking great care and pride in their work. Helen in the office, along with Marius, were always on hand to keep us updated on progress and talk us through the different choices and options available.

It was also really helpful having a clear contract in place detailing exactly what was included in the agreed costs. This made budgeting much easier and meant there were no unexpected or surprise costs along the way.

We can’t wait for the final touches to be completed so we can start enjoying our family’s new space. Thank you to the whole team for all your hard work — we’re really happy with the result!
  
 
     Posted on Google  
   
   Alex Moon 
 28 September 2026
 
 
 Trustindex verifies that the original source of the review is Google. The loft room team were great. John was very respectful, and kept us informed on progress. Going the extra mile to make our new space amazing. They really managed to maximise the floor space to create a great sized master bed and en-suite.
  
 
     Posted on Google  
   
   Calum Millar 
 26 September 2026
 
 
 Trustindex verifies that the original source of the review is Google. Recently had a dormer loft conversion completed by Ash and Alfie of The Loftroom.

From design all the way through to finishing the construction the team have been great. Quality of the work is outstanding, kept informed and updated all throughout the build, and always consulted about the specifics.

Highly recommend.
  
 
     Posted on Google  
   
   Chris Talbot 
 25 September 2026
 
 
 Trustindex verifies that the original source of the review is Google. We are delighted with our new loft conversion by The Loft Room. The whole process went incredibly smoothly, from the planning stage all the way through to decorating.

A huge thank you to Vio, who led the team on our project. Vio and the team’s hard work and dedication has transformed our house. Vio kept everything running on track, maintained a high standard of work, and was always a pleasure to deal with. He and his team treated our home with respect and made sure the details were done right. And also, a special mention to all in the office whose excellent communication kept us in the loop throughout.

We would heartily recommend The Loft Room to anyone looking to do a loft conversion. Thanks guys!

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Exterior finish options

To ensure that your Mansard conversion compliments the original property, we match all exterior finishes to what is present as best as possible. The exterior finish of your Mansard loft conversion can either be brick, tile or slate hung. The tile or slate will be chosen on site so that they match the existing roof as close as possible. If you decide on brick, the brick used will be the equivalent of the existing brickwork. Other external finishes such as fascia’s, soffits, gutters and windows will also be matched as close as possible with the rest of the property.

Will you need planning permission?

If your property has permitted development rights, you can build a Mansard conversion under a Certificate of Lawfulness. This certificate means that, as long as you build within the council’s guidelines, you do not need to wait for the application to be approved before work commences.

If you do not have permitted development rights, you will need to obtain planning permission. With planning permission, you cannot start work until it has been granted. Once a planning application is received by your council, it usually takes around 8 weeks for a decision to be made.

Here at The Loft Room, we will ascertain exactly which permission is needed and will submit the relevant applications on your behalf to obtain the correct approval.