Permitted Development Rights in London: What You Can Build Without Planning Permission

Under Part 1, Class A of the General Permitted Development Order (GPDO 2015), a London homeowner can extend to the rear of their property without planning permission, subject to the following conditions: For a detached house in London: single-storey rear extension permitted to a maximum depth of 8m from the rear wall of the original dwelling, maximum height of 4m at the ridge (3m at the eaves). Two-storey or above: maximum 3m depth from the rear wall of the original dwelling. For a semi-detached or terrace house in London: single-storey rear extension permitted to a maximum depth of 6m from the rear wall of the original dwelling. Two-storey: maximum 3m depth. Important caveats for London terraces: the depth measurement is from the rear wall of the original dwelling as built (not as extended by previous works). If the property has previously been extended, the remaining PD allowance is reduced. The extension must not cover more than 50% of the garden area. The extension must not be higher than the existing property's eaves height on the side elevation nearest to a boundary with another property. Materials must be similar in appearance to the existing house. No verandas, balconies, or raised platforms on the extension. Larger Home Extension Scheme (Prior Approval): single-storey rear extensions to greater depths than the standard PD limits (up to 8m for detached, up to 6m for terraces and semis) are possible under the Larger Home Extension Scheme via a Prior Approval application to the London Borough. The Prior Approval process involves notifying neighbours and giving the London Borough 42 days to consider the application — neighbours can object, and the Borough can assess the impact on amenity. Note: many London Borough planning policies in conservation areas have Article 4 Directions that restrict rear extension PD rights — check with the London Borough before relying on PD.

Under Part 1, Class B of the GPDO, London homeowners can extend into the roof space of their property without planning permission, subject to: Volume limits: for a detached house: maximum 50 cubic metres of additional roof space. For any other house (terrace, semi-detached): maximum 40 cubic metres. The volume is measured from the highest point of the ridge of the original roof to the relevant parts of the loft structure being altered — this is not always straightforward to calculate and professional guidance is recommended. No extension beyond the plane of the existing roof slope on the principal elevation (the elevation facing the highway). Rear dormers: a rear dormer can be added within the PD volume limits — it must not be higher than the existing roof ridge. Side dormers: side dormers are not permitted development (they would be visible from the street). Materials: similar in appearance to the existing house. No verandas, balconies, or raised platforms. Conservation area considerations: in London conservation areas, rear dormers are generally PD (not visible from the street), but hip-to-gable conversions and front dormers are not PD — a planning application is required. Article 4 Directions in some London conservation areas remove all Class B PD rights, requiring planning permission for any roof extension. Pre-application check: the volume calculations for a London Victorian hip-to-gable conversion are complex. Always confirm PD compliance with a planning consultant before starting works — a Certificate of Lawful Development (proposed) provides certainty that the works are lawful without requiring a full planning application.

Under Part 1, Class E of the GPDO, London homeowners can build outbuildings (garden offices, sheds, garden rooms, summer houses, greenhouses) within the curtilage of their dwelling without planning permission, subject to: Location: outbuildings must be in the rear garden (not forward of the principal elevation) or to the side of the house (but only where the outbuilding is more than 20m from any highway). For London terrace properties, outbuildings must be in the rear garden only — there is no side garden in most cases. Height: single-storey outbuildings: maximum 4m height (pitched roof) or 2.5m if within 2m of the boundary. An outbuilding with a 2.4m wall height and a shallow pitched roof entirely within 2m of the boundary: not PD (exceeds 2.5m limit). Maximum eaves height 2.5m for any outbuilding. Area: outbuildings must not, when combined with any other outbuildings, swimming pools, or other structures, cover more than 50% of the garden area. Habitable rooms: an outbuilding that will be used as a separate sleeping accommodation (a self-contained annex or granny flat) is not PD — it requires planning permission as a change of use. Outbuildings in conservation areas: in London conservation areas, Article 4 Directions often remove PD rights for outbuildings on the rear curtilage — planning permission may be required even for a small garden office. Check with the London Borough.

London has hundreds of conservation areas covering large proportions of many inner London Boroughs — including Kensington, Chelsea, Islington, Hackney, Wandsworth, Richmond, and many others. In conservation areas, the general rules are: Standard PD rights apply to rear extensions and rear loft works (subject to the general limits). However, many London Boroughs have made Article 4 Directions removing specific PD rights in conservation areas. Common PD rights removed by Article 4 Directions in London conservation areas: Cladding of the exterior of a dwelling with stone, artificial stone, pebble dash, render, timber, plastic, or tiles (Part 1, Class A condition — materials). Window and door replacement on the principal elevation: any change in the appearance of front-elevation windows or doors may require planning permission. Front garden hardstanding: covering more than 5m² of a garden with non-porous materials, or any amount of garden on the principal elevation visible from a highway, may require planning permission in conservation areas. Dormer windows on the principal elevation. Roof extensions visible from the street. Key practical advice for London conservation area homeowners: before starting any external works (extension, roof works, cladding, windows, external structures), check the Article 4 Direction for your specific London Borough and street. A pre-application consultation with the council will clarify what requires planning permission.

The Certificate of Lawful Development (CLD) is one of the most useful tools available to London homeowners who want certainty about whether their proposed works are PD: What a CLD does: a CLD is issued by the London Borough as a formal legal confirmation that a proposed development is lawful (as PD, or as a use that requires no permission). A CLD is a planning certificate, not a permission — it confirms what is already lawful. When to use a CLD: where there is any uncertainty about whether a proposed extension, outbuilding, or roof conversion falls within the PD limits; where the property is in a conservation area with Article 4 Directions and the homeowner needs certainty about what requires planning permission; where the homeowner intends to sell the property and wants to provide written confirmation that works were lawful. Cost of a CLD application: application fee: £258 (£129 for permitted development works, doubled for most PD applications — confirm with the specific London Borough). Application time: 8 weeks (same statutory period as a planning application). Professional fees (planning consultant or architect to prepare and submit the CLD): £800-£2,500. The CLD is not required to build under PD — London homeowners can build without it. But it provides certainty, protects against enforcement action, and is valuable when selling the property. Practical summary: PD rights are a minimum standard — a London Borough can restrict them via Article 4 Direction, but cannot grant more than the PD rules allow. Always check the specific Article 4 Directions for your London Borough and street before relying on PD for a significant project.