For London homeowners planning an extension, loft or garden room
Permitted Development Rules in London: What You Can Build Without Planning Permission
Sviatoslav JerdetchiiCEO & Founder of Craftex. Updated , 8 min read
The short answer
Permitted development is planning permission granted by national law for set types of work to a house: rear and side extensions, loft conversions, rooflights, porches, outbuildings and driveways. In London the rights are the same as anywhere in England, but they are cancelled more often: by a flat, a conservation area, a listed building or an Article 4 direction.
- A house can have a single-storey rear extension of 3 m (4 m if detached), or 6 m (8 m) with a prior approval, and a loft of 40 m³ (50 m³) without an application.
- Flats and maisonettes have no householder rights at all. Conservation areas lose lofts, side extensions, cladding and two-storey rear extensions.
- Building Regulations and the Party Wall Act still apply. A lawful development certificate is the only paper that proves the work was permitted.
Permitted development rules are national law that grants planning permission in advance for set works to a house. If your project fits one of the listed classes, you can build without a planning application. For a London house that covers a rear or side extension, a loft, rooflights, a porch, a garden room and a driveway.
The catch is the word house. Flats have none of these rights. A conservation area removes several. A listed building, an Article 4 direction or a condition on an old permission can remove the rest.
In our experience the expensive mistake is not a refusal. It is a scheme drawn before anyone checked the address. This guide sets out the limits and the questions that decide whether they still apply to you. Want it checked now? Book a site visit and we will do it for free.
What permitted development is
The rules sit in one document: the Town and Country Planning (General Permitted Development) (England) Order 2015. Schedule 2, Part 1 of that Order lists the works a homeowner may do to a house. Each class has limits, and work that breaks one limit needs a planning application for the whole project.
The first test is the building. The Order's definition of a dwellinghouse excludes any building containing one or more flats, and any flat in such a building. A maisonette counts as a flat. So a converted house split into two flats has lost its householder rights, and so has a purpose-built block.
Three more things remove rights before you look at the limits:
- Article 2(3) land. Conservation areas, National Parks, areas of outstanding natural beauty and World Heritage Sites. In London that means conservation areas, which cover a large share of inner London streets.
- Listed buildings. Any alteration or extension that affects the character of a listed building needs listed building consent, whatever the Order says.
- Article 4 directions and conditions. A council can withdraw a class for a street or a borough. A planning permission for a new house or a conversion can carry a condition removing the rights too.
The permitted development rules, class by class
Each class below is quoted from Schedule 2, Part 1 of the Order as in force in November 2026. The figures are national. London has no extra allowances and no London-only cuts, only more land where the cuts apply.
| Class | What it covers | Main limits |
|---|---|---|
| A | Extensions and alterations | Single-storey rear 3 m (4 m detached), 4 m high; two storeys 3 m deep and 7 m from the rear boundary; side single storey, half the width |
| B | Roof enlargements (lofts, dormers) | 40 m³ terrace, 50 m³ other; not above the ridge; not on the front slope facing the street |
| C | Other roof alterations (rooflights) | No more than 0.15 m above the roof plane |
| D | Porches | 3 m² floor, 3 m high, 2 m from a highway boundary |
| E | Outbuildings and garden rooms | Half the garden; eaves 2.5 m; 4 m dual-pitched, 3 m flat, 2.5 m within 2 m of a boundary |
| F | Hard surfaces | Over 5 m² at the front must be porous or drain to the garden |
| G | Chimneys and flues | No more than 1 m above the roof |
| H | Antennas | Two at most, none over 1 m |
Class A: extensions
A single-storey rear extension may project 3 m beyond the original rear wall, or 4 m on a detached house, up to 4 m high. Within 2 m of a boundary the eaves must stay under 3 m. Nothing may rise above the existing roof, and nothing may go in front of the principal elevation.
A larger single-storey rear extension of 6 m, or 8 m on a detached house, is also permitted, but only after a prior approval. You notify the council, and it writes to the adjoining owners, who have 21 days to object.
If nobody objects, or the council approves, you may start. If the council says nothing for 42 days, you may start anyway.
Two-storey rear extensions are tighter: 3 m deep at most, and no closer than 7 m to the boundary opposite. Side extensions must be single storey, under 4 m high and no wider than half the original house. All extensions together, including earlier ones, may cover no more than half the land around the original house.
Materials must look similar to the existing house. Upper-floor side windows must be obscure-glazed and fixed shut below 1.7 m. No balconies, verandas or raised platforms are allowed under any class.
Class B and C: lofts and roofs
A loft enlargement may add 40 m³ to a terraced house or 50 m³ to any other house, measured against the original roof. The new roof may not rise above the existing ridge or extend beyond the slope that faces the street.
Dormers must be set back 0.2 m from the eaves, as far as practicable, and use similar materials. Class B does not apply on article 2(3) land at all.
Rooflights fall under Class C and may stand no more than 0.15 m proud of the roof. That is why a conservation-area loft usually keeps rooflights and loses the rear dormer.
Class D to H: porches, outbuildings and the rest
A porch may have a floor of 3 m² and a height of 3 m. It must sit 2 m or more from a boundary with a highway.
An outbuilding under Class E must be single storey and used for a purpose incidental to the house. A study, gym, store or pool room qualifies; a bedroom or a self-contained flat does not. It may not stand forward of the principal elevation.
Eaves are capped at 2.5 m. The overall height is capped at 4 m with a dual-pitched roof and 3 m otherwise. Within 2 m of a boundary the cap is 2.5 m.
On article 2(3) land it may not sit between a side wall and the boundary. There is no Class E right in the curtilage of a listed building.
A new front driveway over 5 m² must be porous or drain to a lawn or bed. A flue may rise 1 m above the roof, but in a conservation area it may not sit on a street-facing wall or slope.
Where the rights stop in London
London is where permitted development most often fails, and for four reasons.
- Flats and maisonettes. No householder class applies. Every extension, dormer or garden room on a flat needs an application.
- Conservation areas. These are article 2(3) land. Class B goes entirely, so no loft enlargement. Class A loses side extensions, two-storey rear extensions and cladding. Class E loses buildings at the side. A plain single-storey rear extension usually survives.
- Listed buildings. The Order does not override listed building consent, and outbuildings lose their class altogether.
- Article 4 directions. A council can remove any class for a defined area. Boroughs use them for conservation areas, for HMOs and for office-to-flat conversions. Our guide to Article 4 directions in London lists the ones we have verified borough by borough.
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Proving it: the lawful development certificate
Permitted development is self-assessed. Nobody at the council signs it off unless you ask. The way to ask is a lawful development certificate under section 192 of the 1990 Act. The council must issue it if the work would be lawful. The lawfulness is then conclusively presumed unless the facts change before you start.
The certificate matters twice. It protects you from an enforcement notice if an officer later measures the extension differently. And it answers the buyer's solicitor when you sell. Since 25 April 2024 the enforcement time limit in England is ten years from completion. An unverified extension is a question on the sale for a decade.
What permitted development does not cover
Three regimes sit outside planning and apply whether or not you needed permission.
- Building Regulations. The GOV.UK guidance is blunt: Building Regulations approval is different from planning permission, and you might need both. An extension, a loft and any structural opening need approval and a completion certificate.
- Party Wall etc. Act 1996. Work to a shared wall, building at the boundary or digging below a neighbour's foundations needs a notice. The Act is separate from planning.
- Leases and covenants. A freehold house with a restrictive covenant, or a long leasehold house, may need the freeholder's consent as well.
If the rights have gone: the householder application
When a class fails, the route is a householder planning application. The fee for a single house is £528. The council judges the design against its local plan rather than the Order's fixed figures. That cuts both ways. A well-designed 4 m extension in a conservation area is often approved where a 3 m box would have been permitted.
Our planning consultancy and planning permission team prepares householder applications for the schemes we will build. The drawings submitted are the drawings priced. If the application is refused, the same team handles the appeal.
Commercial permitted development in one paragraph
Commercial buildings have their own classes in Part 3 of the Order. The one investors ask about is Class MA. It turns offices, shops and other Class E uses into flats with a prior approval rather than a full application.
Since 5 March 2024 there is no floorspace cap and no vacancy test. The building must have been in Class E use for two years and must not be listed. Our permitted development for conversions service covers that route; this guide stops at the house.
How we check and build it
We have designed and built London extensions, lofts and refurbishments as one team since 2016, with construction in-house. The permitted development check comes first and costs nothing. Send us the address and the idea. We come back with what can be built without an application, what needs one, and a price for the works.
Our home renovation and refurbishment projects start from £100,000. This is for an extension, loft and refurbishment done together, not a single small job. If that is your project, book a site visit and we will walk the house with you.
Before you commission drawings
- Confirm the building is a house, not a flat or maisonette.
- Check the conservation area map and the Article 4 register for the address.
- Read the planning history: any condition removing permitted development rights.
- Measure from the original house, not from an earlier extension.
- Decide whether to apply for a lawful development certificate before you start.
- Budget for Building Regulations, a party wall surveyor and the structural design.
