Dormer, hip-to-gable or mansard: which loft conversion?
The roof decides most of it. Terraces and semis with a pitched rear roof usually suit a rear dormer. Semis and detached houses with a hipped (sloping) side roof suit a hip-to-gable conversion, usually with a rear dormer. Terraces where neighbours already have mansards, or where you want the most space, suit a mansard. A rooflight conversion is cheapest but needs enough head height already.
How do the main types compare?
| Type | Best for | Pros | Cons | Typical cost |
|---|---|---|---|---|
| Rooflight | Tall roofs | Cheapest, quickest, roof shape unchanged | Least floor space with full head height | £30,000 to £45,000 |
| Rear dormer | Terraces and semis | Lots of usable space, often permitted development | Boxy look from the rear | £50,000 to £65,000 |
| Hip-to-gable | Semis and detached with hipped roofs | Unlocks space in hipped roofs | New gable changes the side view | £60,000 to £80,000 |
| Mansard | Terraces, city streets | Almost a full extra storey | Usually needs planning, costs most | £65,000 to £85,000 |
Which adds the most space?
A mansard gives the most, followed by a full-width dormer and a hip-to-gable with dormer. A rooflight conversion adds the least floor area with full head height.
Which is quickest to get approved?
In England, rooflight, rear dormer and hip-to-gable conversions are often permitted development, so a lawful development certificate (optional) is usually all that is needed on the planning side. Mansards usually need a full planning application.
Related projects
This guide is general information about building work in the UK, not legal or tax advice. Rules change, so check the current position for your property with the council, HMRC or a qualified adviser before relying on it.