Permitted Development Checklist for London Home Extensions

PD rights may be restricted or removed entirely for:

Listed buildings: No PD rights for any works affecting the external appearance. All works require Listed Building Consent.

Conservation areas: PD rights are limited for extensions in conservation areas. Extensions that are visible from the highway (front, side, or visible-from-road rear) are restricted. In many London conservation areas, side extensions require planning permission. Confirm with your borough.

Article 4 Direction areas: Many London local authorities have removed PD rights for specific types of development by Article 4 Direction. Common examples include removal of C3→C4 HMO change rights, and removal of householder extension PD rights in certain areas. Check your specific address on your borough's interactive planning map.

Flats and maisonettes: No PD rights at all for flats and maisonettes. All works require planning permission.

New-build properties where PD rights were removed by condition: Some new developments have planning conditions removing permitted development rights. Check the original planning permission for your property if it was built after approximately 1960.

If any of the above apply, stop here and apply for planning permission.

For a standard house (not flat, not listed, not in a conservation area, not subject to Article 4 Direction removal of PD rights):

Size:

• Extension depth from the original rear wall does not exceed 3m for a semi-detached or terraced house
• Extension depth does not exceed 4m for a detached house
• OR
• Under the Larger Home Extension Scheme (prior approval route), depth up to 6m (semi/terraced) or 8m (detached) — prior approval from the local authority is required but is not the same as full planning

Height:

• Maximum height of the extension does not exceed 4m
• If within 2m of the rear boundary, maximum eaves height does not exceed 3m
• For a flat roof, maximum height does not exceed 3m overall if within 2m of the boundary

Width (if side element is included):

• Extension does not extend beyond the side wall of the house
• If the extension includes a side element, the combined extension does not exceed half the width of the original house

Materials:

• Materials match the existing house in appearance, as far as practicable

Windows and doors:

• Any upper-floor side windows are either obscure-glazed or positioned so the bottom of the glazing is more than 1.7m above floor level (to prevent overlooking neighbours)

Other:

• Extension does not include a veranda, balcony, or raised platform
• The roof of the extension is not a balcony or accessible terrace

Two-storey rear extensions face stricter limits:

• Extension depth does not exceed 3m from the original rear wall
• Extension is no closer than 7m to the rear boundary
• Materials match the existing house
• Upper floor windows facing the side boundary are obscure-glazed or 1.7m+ above floor level
• Eaves and ridge height do not exceed the main house

Side extensions are the most restricted category:

• Property is not a semi-detached house on a corner plot visible from the highway (these are typically not PD)
• Property is not in a conservation area (side extensions are often not PD in conservation areas)
• Extension is single-storey only
• Extension is set back from the front wall of the house by at least 0.5m
• Maximum height of 4m
• Maximum width does not exceed half the width of the original house

Outbuildings (garden rooms, garages, workshops) have their own PD rules:

• Not in front of the principal elevation of the house
• Maximum height of 2.5m if within 2m of a boundary; 4m for a pitched roof or 3m for other roof forms if more than 2m from the boundary
• Total area of outbuildings plus extension does not exceed 50% of the original curtilage (garden) area
• Not used as a separate dwelling

Under the Larger Home Extension Scheme, you can build a larger extension than the standard PD limits — up to 6m for semi-detached and terraced houses and 8m for detached houses — without full planning permission, provided:

• You notify the local authority before starting work
• The authority consults neighbours
• No objections are raised within 21 days that the authority considers material

This is a prior approval process — it is not automatic, but it is not a full planning application either.

If any item on the checklist is unclear:

1. Contact your local authority planning department's pre-application advice service
2. Commission a planning consultant to provide a lawful development certificate (LDC) — a formal written confirmation that your proposal is PD. This is not the same as planning permission but provides legal certainty and is bankable for future buyers

A Lawful Development Certificate for a standard rear extension typically costs £100–£250 in council fees plus any agent or professional fees.

Never assume your extension is PD without checking. Starting works that turn out to require planning permission can result in enforcement action, enforcement notices, and the requirement to demolish the work.

rcbGroup reviews the PD position of every extension project at the pre-construction stage and advises on the appropriate route before design is finalised.