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.
Mansard loft

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.

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Ben Chadwick profile picture
Ben Chadwick
22 August 2026
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We have just had our loft completed by the loft room. They were really easy to work with, took care of all the paperwork. They were great at communicating all the stages and their response time was excellent. Adrian was our builder and he was fantastic. Super thorough, reliable, fast, tidy and often gave us suggestions when we were unsure. The whole project was finished in about 6weeks! We wouldn’t hesitate to recommend The Loft Room to anyone. Many thanks!
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Ken O'Neill
19 August 2026
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We are so happy we decided to go ahead with The Loft Room. Everyone we met from our initial consultation with Paul to Lulian and his team and Helen and Melissa in the office have been great. We were especially impressed with the hard work of Lulian and his team even through the heatwave. They were friendly and professional and always ready to answer any questions we had. Thanks to Lulian for suggesting bigger Velux windows - they are amazing! All the trades involved were great - we will definitely use them again in the future. The work was completed on time and we are really happy with it. We would certainly recommend The Loft Room.
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jasmine zohdy
17 August 2026
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We used the loft room for our loft extension and are very pleased with the results. We were lucky enough to have Adrian and Andre build the dormer, the whole experience was excellent from start to finish. The work was completed incredibly quickly, yet the quality remained consistently high throughout. Adrian brought great ideas to the project that genuinely improved the final design, and he kept everything neat and tidy every single day. All the trades they works with — electrician, roofer, plumber and more — were equally reliable and skilled. There were no delays at any stage; each team arrived exactly when needed and kept the project moving smoothly. The administration side Helen and Mellisa was also superb, with clear updates and communication about progress and next steps. A very professional service all round.
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Amy Dobson
6 August 2026
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Off the recommendation of friends we engaged the Loftroom to refresh and extend our existing loft conversion, adding new insulation, skylights, a new shower room and additional bedroom. We have never done major work to a property before so benefited greatly from loft room supporting us start to finish with planning, designs and all the various trades needed. Our team lead Marius was excellent from start to finish. Him and his team were incredibly hard working, working quickly and to a very high standard. We were really impressed especially given they worked through multiple heat waves !!Their advise and guidance during the build was invaluable (see skylight in shower room!). We wouldn’t hesitate to recommend Marius and the wider loft room team (who were very supportive every step of the way) to anyone looking to complete a loft conversion or improve an existing one.
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Andrea Guerra
4 August 2026
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We recently completed a loft conversion with The Loft Room, adding two generous rooms, a bathroom and a proper landing, and we are delighted with the result. The new floor feels like a natural part of the house rather than an addition, and the quality of the finished space is excellent. A special mention must go to Dave, who managed the project with patience, kindness and a genuine commitment to getting things right. Building work inevitably brings challenges and changes along the way, but Dave was consistently approachable, practical and willing to find solutions. He took real pride in the work and cared about the final outcome, which made a significant difference to us. The whole team worked incredibly hard in our home, and we are very grateful for what they created. It was a major project for our family, and the additional space has genuinely transformed how we can use and enjoy the house. We would happily recommend The Loft Room and especially Dave.
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Brooke Owusu-Bempah
27 July 2026
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Getting a loft conversion done is a big decision. We were honestly quite nervous about it, especially given the investment involved and the number of horror stories you hear about building projects going wrong. Thankfully, our experience with The Loft Room was the complete opposite. From day one, the whole process was handled brilliantly. Everyone we dealt with, from the office team through to the various tradespeople who worked on our home, was professional, friendly and incredibly well organised. What impressed us most was that our loft was completed in just 9 weeks, and the quality of the workmanship never felt rushed. A special mention has to go to Ashley C. He wasn't just the team leader overseeing the project. He was the lead carpenter and the driving force behind the entire build, coordinating all of the contractors, managing the day-to-day work, and making sure everything stayed on track. More than that, he felt like a genuine partner in the project. He understood that we had a budget to work within, took the time to listen, offered great ideas to maximise the space, and always made us feel completely comfortable and informed. His communication was exceptional throughout. No question was ever too small, no concern was ever brushed aside, and he was always happy to walk us through things, sometimes more than once when we needed reassurance. Having someone like Ashley on site every day made what could have been a stressful experience feel surprisingly straightforward and enjoyable. Every contractor who came into our home was polite, respectful and highly skilled. There wasn't a single issue throughout the build, and it was obvious that everyone took pride in their work. In fact, by the end of the project, it was genuinely a little sad to see the team finish. Ashley had become such a reassuring and professional daily presence that we'll genuinely miss seeing him and the crew around. We're now at the final decorating stage and can't wait to move into and enjoy our beautiful new space. We've been talking about our experience to anyone who'll listen, recommending The Loft Room to neighbours and friends, and proudly showing people the transformation. If you're considering a loft conversion, we honestly couldn't recommend The Loft Room highly enough. They've completely exceeded our expectations in every way. 10/10 for quality, professionalism, communication and customer service. And if you're lucky enough to have Ashley C. leading your build, you'll be in extremely safe hands. He played a huge part in making our project such a success.
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Harry G
20 July 2026
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We had our loft conversion completed by The Loftroom Teddington at the start of the year, and we're absolutely delighted with the finished result. The extra space has made such a difference to our home, and the quality of the work has been excellent. A big thank you to Ash, who did a fantastic job and was always friendly, hardworking, and happy to answer any questions we had each morning (and throughout the day!). We'd also like to thank Paul, who was great from our very first interaction, as well as Melissa and Helen in the office, who kept everything running smoothly, and Rich, who regularly popped in during the build to check on progress. As with any building project, there were a few small niggles, but these were dealt with quickly, professionally, and efficiently. It was reassuring to know that the team stood by their work and were committed to making sure everything was right. Overall, we've had a really positive experience from start to finish and wouldn't hesitate to recommend The Loftroom Teddington to anyone considering a loft conversion. Thank you to the whole team!
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nick davis
17 July 2026
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Marius and his team were punctual, quick and clean and did a good job on our loft extention. Would recommend them.
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A Z
15 July 2026
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Many thanks to Paul, Melissa, Helen, Maggie and our project manager Mihai! The whole team is great, and the tradespeople they used are highly professional and do excellent work. Thank you for delivering my project right on schedule and with fantastic results.
Mansard Loft External

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.

FAQs

Call us now for a FREE no-obligation quotation on 0800 002 9291

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