Loft conversion in Merton

Common across Wimbledon, Colliers Wood and Morden under permitted development outside the protected areas. In the Wimbledon conservation cluster and the planned Edwardian Article 4 streets, dormer form is decided through a full application. Building regulations always apply.

Common across Wimbledon, Colliers Wood and Morden; the John Innes and Wimbledon conservation areas decide dormer form via a full application.

Rear dormers are a staple on unconstrained Victorian and interwar roofs. In the higher-scrutiny conservation areas, roof form and materials are closely controlled; rear-facing dormers that follow the street pattern have a better record than box forms or front alterations. The Article 4 planned streets pull roof changes into planning even where a homeowner might otherwise expect a certificate-only route.

Permitted development (GPDO Class B) allows roof enlargements up to 40m³ on terraced houses and 50m³ on semis and detached — enough for a substantial rear dormer — provided nothing projects beyond the roof plane of the principal elevation, materials are similar, and dormers sit back from the eaves. Class B is excluded in conservation areas.

In conservation areas the route is a full application, and roof form decides it: rear mansards with traditional slate and proportioned dormers have a strong record on Victorian terraces; box dormers and front-facing alterations are the classic refusals. Article 4 directions (Muswell Hill is the local example) pull roof works into planning control even where conservation policy alone might not.

Whatever the route, building regulations approval is always required — fire escape, stair geometry and floor structure — and a Lawful Development Certificate is cheap insurance on PD schemes.