Do I need planning permission for a loft conversion?
A clear answer plus the volume limits, design rules, and conservation-area exceptions for UK loft conversions.
Permitted development limits (England)
Under General Permitted Development Order (GPDO) Class B, most loft conversions don't need planning permission if they meet ALL these:
- Volume added is less than 40m³ for terraced houses
- Volume added is less than 50m³ for semi-detached or detached houses
- No part of the extension is higher than the highest part of the existing roof
- No extension extends beyond the plane of any existing roof slope facing a highway (front)
- The extension is set back at least 200mm from the eaves
- Materials look similar to the existing house
- No verandas, balconies or raised platforms
- Side-facing windows have obscure glazing and are non-opening (or opening parts are at least 1.7m above floor)
- Roof pitch matches the existing where possible
When you DO need planning permission
- Volume exceeds the limits above
- Property is in a conservation area, AONB, National Park, the Broads, or World Heritage Site
- Property is listed (always need listed building consent regardless)
- Property has had permitted development rights removed (Article 4 direction or planning condition)
- It's a flat or maisonette (permitted development doesn't apply)
- You're adding a front-facing dormer visible from the street
Building Regulations always apply
Even if you don't need planning permission, Building Regulations always apply to a loft conversion. Structural calculations, fire safety, insulation, stairs, and electrical work all need to be approved by Building Control or an Approved Inspector.
Lawful Development Certificate
If you're sure your conversion is permitted development, it's still worth applying for a Lawful Development Certificate (LDC). This is a formal council document confirming the work didn't need planning. Costs about £100–£200 and is invaluable when you sell — buyers' solicitors often ask for it.
Official sources
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Frequently asked questions
Velux-only conversions (no dormer or roof extension) almost always fit within permitted development as the roofline doesn't change. Always confirm with your council.
Side or rear dormers are usually permitted development if they meet the volume limits. Front-facing dormers visible from the highway always need planning.
Often goes over the volume limit and exceeds permitted development. Plan for full planning application.
All loft extensions in conservation areas need full planning — permitted development is removed.
Related
Last reviewed: May 2026 · This information is general guidance and not legal advice.
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