Loft Conversion Planning Permission London — Do You Need It?

Permitted Development Rights for Loft Conversions

Most loft conversions in England fall under Permitted Development (PD) rights — which means you can build without submitting a full planning application, as long as you stay within defined limits.

The PD rules for loft conversions (under Class B of the General Permitted Development Order 2015) allow:

- Up to 50m³ additional roof space for detached and semi-detached houses - Up to 40m³ for terraced houses - No extension beyond the existing roof ridge - No extension at the front of the house that would be visible from a highway - Side-facing windows must be obscure-glazed and non-opening below 1.7m height - Materials to be similar in appearance to the existing house

When You DO Need Full Planning Permission

Conservation Areas: If your property is in a designated Conservation Area, you cannot add a rear dormer or hip-to-gable extension under PD. All roof alterations in Conservation Areas require full planning permission from the Local Planning Authority (LPA).

Article 4 Directions: Many London boroughs have removed PD rights for residential properties via Article 4 Directions. This is particularly common in the following boroughs: Islington, Hackney, Tower Hamlets, Southwark, Lambeth, Wandsworth, Hammersmith & Fulham, Camden, Kensington & Chelsea, and Westminster. If your property is in one of these boroughs, assume full planning is required and check with the LPA before proceeding.

Listed Buildings: Any Listed Building requires Listed Building Consent for any alteration — regardless of whether it falls within PD limits.

Prior Approval: For some loft conversions under PD, you may need to apply for Prior Approval from the LPA (for certain Class B works). This is a lighter-touch process but still requires submission.

How to Check

The quickest way: search your address on the Planning Portal (planningportal.co.uk) and check Article 4 Directions for your area. Alternatively, call SuperBuilder — we have extensive experience navigating planning in every London borough and will advise on your specific property.

Building Regulations — Always Required

Even if no planning permission is needed, Building Regulations approval is mandatory for every loft conversion. This covers structural integrity, fire escape routes, thermal insulation, and sound proofing between the conversion and the floor below. SuperBuilder handles all Building Regulations submissions as standard.

Call 0800 530 0853 for expert planning advice specific to your London property.