A loft conversion is one of the best-value ways to add a bedroom without losing garden. The right type depends on your roof, your budget and what the planning rules allow.
The main loft conversion types
- Rooflight (Velux) — the cheapest; windows sit flush in the existing roof slope.
- Dormer — a box that projects from the roof to add headroom and floor space.
- Hip-to-gable — replaces a sloping hip end with a vertical gable wall, common on semis and ends of terraces.
- Mansard — the most extensive, reshaping the roof for maximum space; usually the most likely to need planning permission.
The planning angle
Many loft conversions are permitted development within volume limits — broadly 40m³ for terraced houses and 50m³ for detached and semi-detached — but front-facing dormers, mansards and homes on designated land often need planning permission. Always check before you build.
See permitted development rights explained for the loft limits, and consider a Lawful Development Certificate as proof. To picture the result first, Unformed’s Building Works render shows the dormer or gable on a photo of your actual roof.
This guide is general information, not legal or planning advice. Planning rules change over time and are applied differently by each local planning authority (LPA). Always confirm the position with your council before starting work. Unformed’s Planning Review gives an AI-assisted risk assessment of a scheme but does not guarantee any planning outcome.