Mansard
A mansard loft conversion rebuilds one or both roof slopes as a near-vertical wall with a flatter roof on top. It creates the most space of the common conversion types and is often seen on terraced houses in towns and cities. Because it changes the shape of the roof significantly, a mansard normally needs planning permission, and it is usually the most expensive type of conversion.
What to Know About Mansard
- Usually creates the most floor space of the common conversion types
- Near-vertical walls give more full-height space across the room
- Often used on terraced houses where other types are limited
- Space for an en-suite or storage, depending on the design
- Normally needs planning permission and costs the most
Price Guide
£50,000–£120,000
Typical UK range, last reviewed September 2026. A guide, not a quote.
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Frequently Asked Questions
Do mansard conversions need planning permission?
Normally, yes. A mansard significantly rebuilds the roof, which usually goes beyond what permitted development allows. You or your designer would apply to the local planning authority; your architect or builder can prepare the drawings. Better Lofts does not make planning applications.
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