Permitted development rights are the reason most London house extensions and loft conversions never go near a planning committee. They are also the source of most expensive mistakes, because the rights that apply to a semi in Bromley may not apply to the same house in a Camden conservation area. This guide sets out what the national rules allow for a house in England, then the three ways London removes them.
What are permitted development rights?
Permitted development (PD) rights are a national grant of planning permission set out in the Town and Country Planning (General Permitted Development) (England) Order 2015. If your project meets every condition of the relevant class, it already has planning permission and you do not need to apply. The rights attach to a “dwellinghouse”, which means a single house. Each class has limits on size, height, position and materials, and each can be switched off locally.
“Permitted” does not mean “unregulated”. PD work still needs Building Regulations approval, still triggers the Party Wall etc. Act 1996 where it touches a shared wall or foundation, and still has to respect leasehold covenants and rights of light.
What can I build under PD on a London house?
The three classes that matter for most householders are Class A (extensions), Class B (roof) and Class E (outbuildings).
| Class | What it covers | Key limits (England) |
|---|---|---|
| A | Rear and side extensions | Rear: 3 m deep (terraced or semi), 4 m (detached); 6 m / 8 m via larger home extension prior approval. Max height 4 m; eaves max 3 m within 2 m of a boundary. Side: single storey, max half the width of the original house. Materials similar in appearance. |
| B | Loft conversions and roof extensions | Extra roof volume of 40 m³ (terraced) or 50 m³ (semi and detached). No dormer on the principal elevation fronting a highway. Not available in conservation areas or Article 4 areas. |
| E | Outbuildings and garden rooms | Max 2.5 m high within 2 m of a boundary; otherwise 4 m dual-pitched or 3 m other roof. Max 50% of the curtilage. Incidental use only, not a bedroom. |
Class A and Class E allowances both count against the same 50% curtilage cap. Class B volume is measured against the original roof, so a house in Waltham Forest with an existing dormer has already spent part of its 40 m³.
Where are PD rights removed in London?
There are three mechanisms, and London uses all three more heavily than most of England.
Property type
Flats and maisonettes have no householder PD rights at all. This catches a large share of London homes: converted Victorian houses in Lambeth and Haringey, purpose-built maisonettes in Southwark, mansion blocks in Westminster. If you own a flat, every extension and every dormer needs a planning application.
Designations
- Conservation areas remove Class B roof extensions entirely and tighten Class A: no side extensions, no cladding, no larger home extension route. London has hundreds of conservation areas; inner boroughs such as Camden, Islington and Kensington and Chelsea are covered extensively.
- Listed buildings need listed building consent for almost everything, and PD rights are effectively irrelevant.
- Other designated land (National Parks, Areas of Outstanding Natural Beauty) also restricts PD, though this rarely affects London homes.
Article 4 directions
An Article 4 direction is a council order removing specific PD classes in a defined area. It is the mechanism that varies most from borough to borough and street to street.
What is an Article 4 direction?
A council can make an Article 4 direction where it believes PD would harm local character or, in the case of Class MA, the supply of business space. The direction names the classes it removes and the area it covers. Once in force, the work in question needs a planning application even though it would be PD elsewhere.
Patterns we see across London, all of which you should verify on the council’s constraints map:
- Many boroughs remove Class A rear extensions and Class B roof alterations within conservation areas, so that even modest changes are assessed on design.
- Several central boroughs, including Westminster, Camden, Islington and Tower Hamlets, have Article 4 directions removing Class MA office-to-residential rights in central and town-centre locations.
- A number of boroughs have removed the right to convert a house into a small House in Multiple Occupation (Class L) across the whole borough.
- Some directions are decades old and map to specific streets or estates rather than whole areas.
Article 4 directions do not change what you can build; they change which process you must follow. A rear extension that would be PD in Ealing may need an 8-week householder application (£528; verify before applying) three miles away in a Kensington and Chelsea conservation area.
Do flats and maisonettes have PD rights?
No. Householder PD (Classes A to H of Part 1 of the Order) applies only to dwellinghouses. A flat or maisonette owner must make a full planning application for an extension, a dormer or, in some cases, a new window. Leaseholders also need the freeholder’s consent, which we recommend securing before drawings are commissioned. Some limited PD exists for blocks as a whole (for example, upward extensions under Part 20), but those rights belong to the building owner and come with their own prior approval process.
Does PD mean I can skip Building Regulations?
No. Planning and Building Regulations are separate systems. PD removes the need for planning permission; Building Regulations still apply to structure, fire safety, thermal performance, drainage, ventilation and access. You will still need a Building Regulations drawing package and either the council’s building control team or a registered building control approver to inspect the work. On a typical London extension or loft the Building Regulations package adds 110–140% of the planning fee and takes 3–5 weeks to prepare.
How do I prove my project is lawful?
Apply for a Lawful Development Certificate (LDC). It is a formal decision by the council that your proposed work is PD, issued after the same 8-week period as a planning application and for half the fee: £264 for a proposed development. If work has already been done, an LDC for an existing use or development costs £528 and requires evidence of when it was built.
We recommend an LDC on every PD project in London, because Article 4 coverage, previous extensions and boundary measurements are all points where a confident assumption can be wrong, and the certificate is what your buyer’s solicitor will ask for. We issue LDC drawings 2–3 weeks after the measured survey and submit within 2 working days of your sign-off.
Related services
- Permitted development and LDCs: PD assessment, drawings and Lawful Development Certificate submission.
- House extensions: rear, side and wraparound extensions under PD or full planning.
- Loft conversions: Class B dormers and full-planning lofts.
- Outbuildings and garden rooms: Class E structures and LDCs.
- Borough guides: Camden and Lewisham.
- Get an instant estimate for a PD assessment.
