Do You Need Planning Permission? Permitted Development Rules by London Borough
By the Golbik GBS team · Blog
The first question for almost every extension or loft conversion in London is whether it needs planning permission. The answer depends on the type of property, the size of the project and, very often, the street you live on. This guide explains the national rules and how they play out in the boroughs where we work.
Key takeaways
- Many house extensions and loft conversions can be built under permitted development, without a planning application.
- Permitted development does not apply to flats and maisonettes, and is restricted in conservation areas.
- Article 4 directions can remove permitted development rights on specific streets.
- A Lawful Development Certificate confirms in writing that a project is permitted development.
- Each London borough has its own conservation areas and local guidance, so the same project can be treated differently.
Permitted Development: The National Rules
Permitted development rights allow certain work on houses without a planning application, as long as the conditions are met. The most relevant ones are:
| Project | Permitted development limit | Main conditions |
|---|---|---|
| Single-storey rear extension | 3 m (attached house), 4 m (detached) | Max 4 m high; materials similar to the house |
| Larger rear extension (prior approval) | 6 m (attached), 8 m (detached) | Council notifies neighbours and can object |
| Side extension | Single storey, up to half the width of the house | Not allowed in conservation areas |
| Loft conversion | 40 m³ (terrace), 50 m³ (semi/detached) | Not on the roof slope facing the street; not in conservation areas |
| Flats and maisonettes | No householder permitted development rights | Planning permission needed |
When You Will Need Planning Permission
- The house is in a conservation area and the work affects the roof, front or side.
- An Article 4 direction has removed permitted development rights on your street.
- The property is a flat or maisonette.
- The project goes beyond the limits, such as a wraparound or two-storey extension.
- The building is listed, which also needs listed building consent.
- An earlier planning condition removed permitted development rights.
Planning in the Boroughs We Work In
The national rules are the same everywhere, but conservation areas, Article 4 directions and local design guidance vary from borough to borough:
| Borough | Areas | What to look out for |
|---|---|---|
| Lambeth | Clapham (most of SW4), Streatham, Brixton | Conservation areas around Clapham Old Town and the Common |
| Wandsworth | Clapham Junction, Battersea, Balham, Tooting | Conservation areas between the Commons; strong local guidance on rear extensions |
| Hammersmith & Fulham | Fulham, Hammersmith | Many conservation areas; mansard roofs judged street by street |
| Kensington & Chelsea | Chelsea | Most of the borough is in conservation areas; many listed buildings and Article 4 directions |
| Southwark | Dulwich, East Dulwich | Dulwich Estate Scheme of Management needs its own consent alongside planning |
| Merton | Mitcham, Wimbledon, Colliers Wood | Fewer conservation areas outside historic centres such as Mitcham Cricket Green |
| Sutton | Wallington and Carshalton, Sutton | Much of the inter-war housing is outside conservation areas; Carshalton Village is protected |
Planning Is Only One of Three Approvals
- Planning permission or permitted development – what you can build.
- Building Regulations – how it is built: structure, fire safety, insulation, drainage, electrics.
- Party Wall Act – agreement with neighbours for work to shared walls. See our Party Wall guide.
For design options, read our guides to extension types and loft conversion types, or see all the areas we cover.
Frequently Asked Questions
How far can I extend without planning permission in London?
Under permitted development, a single-storey rear extension can go up to 3 metres on a terraced or semi-detached house and 4 metres on a detached house. Through prior approval, this can be up to 6 and 8 metres, subject to the council consulting the neighbours.
Do flats have permitted development rights?
No. Flats and maisonettes do not have householder permitted development rights, so extensions, loft conversions and most external changes to flats need planning permission.
What is an Article 4 direction?
An Article 4 direction is a decision by the council to remove some permitted development rights in a specific area, often in conservation areas. Where one applies, work that would otherwise be permitted needs a planning application.
Is a Lawful Development Certificate compulsory?
It is not compulsory, but it is strongly recommended. It is the council’s formal confirmation that the work is lawful, and buyers’ solicitors often ask for it when you sell.
Not Sure What Applies to Your House?
Golbik GBS builds extensions and loft conversions across London and can help you understand the likely planning route before you commit to a design. Contact us to arrange a survey.
Related Guides
- Full House Refurbishment in London: Stages, Permissions and Timeline
- Loft Conversion Types for London Homes
- Side-Return, Rear or Wraparound Extension?
- Planning a Kitchen Renovation in a London Home
- Bathroom Renovation in London: Wet Rooms, Waterproofing and Safety Zones
- Does Your London Home Need Rewiring?
- Upgrading Heating and Plumbing in an Older London Home
- Party Wall Agreements in London: A Homeowner’s Guide
- Extending a 1930s Semi in Sutton, Wallington and Mitcham
- Consumer Unit (Fuse Box) Upgrades Explained
- Renovating a Victorian Terrace in South West London
- How to Choose a Builder in London
