Permitted Development in London: What You Need to Know

Permitted Development (PD) rights allow you to build without full planning permission, but in London they are rarely straightforward. The capital's historic streets and dense housing mean that assuming you have automatic rights can be a costly mistake.

Permitted Development (PD) rights are a homeowner's best friend. Granted by Parliament, these rights allow you to perform certain types of building work and changes of use without having to apply for full planning permission from your local council.

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When it may be permitted development

These are the common features that keep a project on the simpler route.

Rear Extensions: Single-storey extensions up to 3m for a terraced or semi-detached house, or 4m for a detached house (potentially more under the Larger Home Extension prior approval scheme).
Loft Conversions: Up to 40 cubic metres of additional roof space for terraced houses, and 50 cubic metres for detached and semi-detached houses.
Porches: Under 3 square metres and below 3 metres in height.
Outbuildings: Single-storey garden rooms or sheds that take up less than 50% of the curtilage and are not used as primary sleeping accommodation.

When planning permission is more likely

These are the usual triggers that push a scheme beyond straightforward PD rights.

Flats and Maisonettes: Do not have standard Permitted Development rights for extensions. You will almost always need full planning permission.
Conservation Areas: If your home is in one of London's hundreds of Conservation Areas, your PD rights are heavily restricted — roof extensions (dormers) and side extensions are generally not permitted under PD in these zones.
Article 4 Directions: A local council can issue an Article 4 Direction to remove specific PD rights in an area to protect local character. Many London boroughs (like Islington, Southwark, and Richmond) use these extensively to control changes to property frontages or HMO conversions.
Previous Developments: Your PD allowance is based on the 'original house' as it stood on 1 July 1948 (or when it was built, if later). If a previous owner already used up the volume allowance, you cannot add to it under PD.

What CanUBuild checks

Faster answers before you speak to an architect or builder

The tool is designed to answer the first question most homeowners have: is this worth pursuing, and what is most likely to block it?

Address-Level Constraints: We check whether your property is in a Conservation Area, is Listed, sits in a Flood Zone, or is affected by an Article 4 Direction — each of which can remove or restrict your standard Permitted Development rights.

Nearby Planning Precedent: We pull real approved and refused planning applications close to your address, so you can see what the council has accepted on comparable streets before you commit to a scheme.

Permitted Development Eligibility: Based on your property type and the constraints at your address, we assess whether your project is likely to fall within PD rights — or whether a full planning application will be needed.

FAQ

Questions people ask before starting a project

Can I use Permitted Development for a London flat?

No. Flats and maisonettes do not have standard Permitted Development rights for extensions. You will almost always need full planning permission.

Do Conservation Areas remove my PD rights?

Yes, they heavily restrict them. In most London Conservation Areas, works like roof extensions (dormers) and side extensions are not permitted under PD and require a full planning application.

What is an Article 4 Direction?

It is a tool used by local councils — like Islington, Southwark, and Richmond — to remove specific PD rights in an area to protect local character, for instance controlling porch changes or HMO (House in Multiple Occupation) conversions.

Should I get a Lawful Development Certificate?

Yes. Even if you are 100% certain your project falls under PD, an LDC is a legal document confirming your build was lawful, which is essential for future remortgaging or selling the property.

Next step

Check your property before paying for drawings

Search for the address, choose your project type, and get a planning feasibility answer based on permitted development rules, constraints, and local precedent data.

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