What is a mansard loft conversion?

Find out more about the popular mansard loft conversion
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Mansard loft conversions - the basics

A mansard loft conversion involves taking a traditional sloped roof and then extending one side so that it’s almost vertical at the walls and horizontal on top. Whilst this requires the most construction work of any type of loft and changes the structural integrity of the roof entirely, the end result is a drastic increase in space that is almost the equivalent of adding a full extra floor to the house due to the near verticality of the walls.

The roof can be extended this way on just one side of the house, or on multiple sides, with some people opting to have a roof that has been fully extended as a mansard conversion.

How is a mansard loft conversion done?

A mansard loft conversion can be performed on detached, semi-detached, and terraced houses. The more sides of the roof that are available means more sides that can be transformed. A mansard loft conversion nearly always requires planning permission though due to how it affects both roof shape and structure, and thus doesn’t fall into the realms of permitted development as some other types of loft conversion.

A mansard loft conversion effectively involves putting a ‘hinge’ in the centre of the of the roof slope, and then extending it outwards until the hinge approaches a 90° angle so that you have a wall internally that’s almost vertical.

The primary reason for undertaking a mansard loft conversion is that it creates the most space of any loft conversion, maximising what’s available in your property. As mentioned above, it’s versatile too – it can be performed on several slopes of the roof, or just extend a single one in a way that means you can have a mansard conversion but use the other part of your roof as a roof light loft conversion.

They’re also great aesthetically. A hip-to-gable loft conversion provides almost as much space at a smaller overall cost, but is significantly less attractive externally. A mansard loft conversion looks far more natural and can be designed in a way that fits the existing building style.

Are there any downsides to a mansard loft conversion?

The main issue with a mansard loft conversion is that it’s the most disruptive to your house and its structure. This means more work, and ultimately means higher costs. It needs high amounts of architectural input, and the build process is both more intense and longer than any other type of loft conversion.

In addition to this, a mansard loft conversion nearly always requires planning permission due to how it affects the exterior of the house from street level, even if the conversion is only performed on the back of the house.

Overall, a mansard loft conversion easily adds an extra entire storey to your house, but it’s increased cost and disruption can put some people off.

Should I get a mansard loft conversion?

For many, a mansard loft conversion is going to be the best choice. It’s the ultimate package, providing more space than any other type of loft conversion whilst maintaining an aesthetically pleasing and attractive exterior to your house. Whilst these benefits come at an increase in costs and the time it takes to complete the loft conversion, for many it’s worth it. For most of us, we’ll only ever get one loft conversion done throughout our lives, so it can be worth going for the best.

If you’re unsure about which type of loft conversion your should get, or whether a mansard loft conversion is right for you, consider getting in touch with Unique Build. We provide a free consultation and quote to get you started on building your dream loft. We’ll visit your home at a time that suits you, answer any questions you have about getting a loft conversion, and providing you with a great value quote.

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