Planning a home extension in London? It can feel overwhelming, but knowing your rights could save you months of waiting and a lot of money.
Permitted development rights let you make certain changes to your London home without full planning permission, as long as you stick to specific rules and size limits. The government set up these rights so homeowners can extend and improve their properties within set boundaries.
London’s got its own set of challenges, so the rules aren’t always clear-cut. Conservation areas, Article 4 directions, and the policies of different boroughs can all affect what you can actually build.
Plenty of homeowners find out too late that their project doesn’t qualify for permitted development rights in London because of local restrictions they didn’t know about.
This guide gives you the lowdown on extending your London home under permitted development. You’ll get the exact measurements for different types of extensions and learn how to avoid mistakes that could halt your project.
Key Takeaways
- Permitted development lets you build extensions within specific size limits without planning permission applications
- London’s conservation areas and Article 4 directions can restrict or remove your permitted development rights entirely
- You must still comply with building regulations and obtain the proper certificates even under permitted development
Understanding Permitted Development Rights in London
Permitted Development Rights allow London homeowners to make specific home improvements without full planning permission. This streamlines the renovation process and helps cut costs and delays.
These rights come with strict criteria that you need to understand before starting anything.
What Are Permitted Development Rights?
Permitted Development Rights (PDR) are legal allowances that let you carry out certain building work without applying for full planning permission. Parliament sets these rights—not your local council.
The scheme became permanent in 2015. It covers specific types of home improvements like extensions, loft conversions, and some structural changes.
Key areas covered by PDR include:
- Single and two-storey rear extensions
- Loft conversions with dormers
- Side return extensions
- Outbuildings and garden structures
- Some changes of use
You still have to meet strict size limits, height restrictions, and boundary distances. Rules differ across England’s devolved nations, and London has its own specifics.
Conservation areas and listed buildings come with extra restrictions that might limit your permitted development rights a lot.
How Permitted Development Differs from Planning Permission
Permitted development follows pre-approved guidelines, while planning permission needs individual assessment by your local authority. The processes and requirements aren’t the same.
Permitted Development:
- Pre-defined size and height limits
- Automatic approval if you meet the criteria
- No neighbour consultation needed
- Faster implementation (sometimes immediate)
- Lower costs
Planning Permission:
- Case-by-case assessment
- Detailed drawings and statements required
- Public consultation period
- 8-12 week decision time
- Higher fees
If you’ve already extended your property to the max allowed, you can’t use permitted development rights again. Previous extensions count towards your total allowance.
Borough variations can really impact your rights, so you need to do your homework before starting anything.
Key Advantages of Permitted Development
Time Savings: You can start work right away once you confirm your project fits PDR rules. No waiting around for council decisions or neighbour objections.
Cost Reduction: Permitted development means no planning application fees and fewer professional costs. You spend less on planning consultants and architectural submissions.
Reduced Paperwork: The process is lighter on documentation than full planning applications. You just need to make sure you’re compliant with the guidelines.
Certainty: PDR gives you clear boundaries for your project. If you meet the rules, you’re good—no guessing what the council will say.
Privacy: No public consultation, so neighbours can’t formally object if your project complies with permitted development.
You still have to comply with Building Regulations for things like structural safety and energy efficiency. Professional guidance is still a good idea for complex projects to make sure you’re not missing anything important.
Essential Permitted Development Rules for London Homeowners
London homeowners have to follow specific size limits, design standards, and boundary restrictions when using permitted development rights. Some projects will still need full planning permission, no matter what.
Size and Scale Limitations
Permitted development rules set strict size limits for extensions and conversions in London. The idea is to stop overdevelopment but still let people improve their homes.
Single-storey rear extensions can go up to 6 metres from the original rear wall for terraced and semi-detached houses. Detached houses get up to 8 metres.
Two-storey extensions are capped at 3 metres for terraced houses and 6 metres for detached ones. The extension can’t go over 4 metres at the eaves.
Loft conversions can’t increase the roof height by more than 150mm. If you add side windows, they need obscure glazing below 1.7 metres from the floor.
| Extension Type | Terraced/Semi | Detached |
|---|---|---|
| Single-storey rear | 6m | 8m |
| Two-storey rear | 3m | 6m |
| Side return | 3m | 6m |
Volume calculations matter too. You can’t add more than 40 cubic metres to terraced houses or 50 cubic metres to detached and semi-detached ones.
Design and Materials Requirements
Materials used in permitted development projects need to match or complement your existing home. This keeps the neighbourhood looking cohesive and avoids visual messiness.
Roof materials should look like the existing roof in colour and texture. Clay tiles or slate work well for classic London homes.
Wall materials need to blend in with your current external walls. If your house is brick, use similar bricks and pointing styles.
Windows and doors should keep to similar proportions and styles. UPVC windows might clash with period properties or homes in conservation areas.
Boundary treatments like fences or walls shouldn’t go above 2 metres. For front boundaries, the limit is 1 metre unless you’re adding gates or openings.
Your extension can’t stick out beyond the principal elevation facing the road. That way, extensions don’t take over the street scene.
Restrictions on Curtilage and Boundaries
Your property’s curtilage—the area right around your house—sets the limits for what you can build under permitted development. These boundaries affect where and how big your extension can be.
Side boundaries need minimum distances. Single-storey extensions have to be at least 1 metre away, and two-storey ones need 7 metres from any boundary.
Rear boundaries also matter. You can’t build on more than 50% of the original curtilage area around the house.
Neighbouring properties put limits on your rights too. If your extension is over 4 metres high, you can’t build within 2 metres of the boundary.
Shared walls in terraced homes mean you need party wall agreements even with permitted development. This protects your neighbours from structural headaches.
Garden size is important for calculations. Permitted development uses the original garden size, not the current one after previous extensions or outbuildings.
When Full Planning Permission Is Required
Some situations mean you need full planning permission no matter what. These rules protect London’s character and help avoid inappropriate development.
Conservation areas come with extra protections. Lots of permitted development rights are removed, especially for extensions visible from the street.
Listed buildings can’t use permitted development rights for most changes. If your property is Grade I, Grade II*, or Grade II, you’ll need listed building consent.
Flats and maisonettes follow different rules. Most permitted development rights only apply to houses, not flats.
Commercial properties that mix with residential use may lose permitted development rights. The main use of the property decides what rules apply.
Previous extensions count toward your allowance. If you’ve already used up your permitted development rights, you’ll probably need planning permission for more work.
Article 4 directions can remove permitted development rights in certain areas. Many London boroughs use these to control building in sensitive spots.
Permitted Development for Single-Storey Rear Extensions
Single-storey rear extensions can go up to 6 metres for terraced and semi-detached houses, or 8 metres for detached homes under permitted development rules. If you want to go larger, there’s a neighbour consultation process before you can start building.
Depth and Height Limits
Single storey rear extensions have to stick to specific size limits to qualify as permitted development.
Standard depth limits:
- Terraced and semi-detached houses: 6 metres max
- Detached houses: 8 metres max
The extension can’t be taller than the existing house’s eaves or roof. You need to use materials that match or complement your current building.
Permitted development rules also enforce the 50% coverage rule. All buildings in your garden—including extensions and outbuildings—can’t cover more than half your total garden area.
The original house area doesn’t count toward this 50% limit, but existing extensions, sheds, and other structures do.
Consultation and Prior Approval Scheme
Extensions that go beyond 3 metres for terraced or semi-detached homes, or 4 metres for detached houses, need the larger single storey rear extensions neighbour consultation scheme.
You have to apply for Prior Approval before you start building. It costs £96 and usually takes up to 6 weeks for a decision.
The consultation involves:
- Notifying adjoining neighbours
- 21-day consultation period
- Council assessment of neighbour objections
If your extension would cause too much harm to neighbours—like blocking light, invading privacy, or being overbearing—the council will refuse Prior Approval.
Smaller extensions under these size limits skip Prior Approval, but you still need to meet all other permitted development rules.
Guidelines for Side Extensions under Permitted Development
Side extensions under permitted development rights have strict width and height limits set by the government. Where you build the extension also matters—a lot—so you’ll need to check boundaries and existing structures to be sure you qualify.
Width and Height Restrictions
Your side extension can’t be taller than the highest part of your house’s roof. That includes any ridge lines or roof peaks.
The eaves on the extension need to stay below your house’s existing eaves. Eaves are basically where the roof meets the outside wall.
Width limitations include:
- Maximum 50% of your original house width on terraced properties
- No width restrictions for detached houses
- Keep the extension in proportion to the rest of the house
Permitted development rules also say your extension must stay below your neighbour’s sight lines. That’s mainly to protect their light.
If your extension is big, ground coverage becomes a factor. You can’t cover more than 50% of your garden with buildings.
Project Placement Criteria
The whole side extension has to sit within your property boundary. Nothing can stick out past your legal land limits.
Setback requirements specify:
- At least 1 metre from any boundary in most cases
- 2 metres from the rear boundary for two-storey extensions
- Different rules if you’re in a conservation area
Permitted development for side extensions depends on your property type. Terraced homes get stricter limits than detached ones, which honestly makes sense.
You can’t build within 20 metres of a classified road—so, no extensions right up against A-roads or motorways.
Your extension must connect directly to your house. Detached outbuildings count as something else entirely in planning terms.
Windows that face neighbours need careful thought. You don’t want to fall foul of planning rules by overlooking someone’s garden.
Two-Storey Rear Extensions: What is Permitted?
Two-storey rear extensions under permitted development face tough limits on depth and height, plus rules about obscured glazing for neighbour privacy. The rules are stricter than for single-storey extensions, so you’ll need to plan carefully to get it right.
Maximum Depth and Height
Two-storey rear extensions can only go 3 metres out from your original rear wall. That’s a lot less than the 6-8 metres allowed for single-storey builds.
You need a minimum 2-metre gap between each side wall of your extension and your property boundary. For terraced homes, this rule pretty much makes two-storey extensions impossible, and it’s still tricky for semi-detached properties.
Height restrictions include:
- Extension can’t be higher than your house’s tallest roof point
- Eaves must stay below your house’s existing eaves
- You can only build the extension at the rear of the property
You can’t push your total building coverage over 50% of your curtilage. That includes all existing extensions and outbuildings, not just the new bit.
Obscured Windows and Privacy Conditions
First-floor windows in your two-storey extension that overlook neighbours need to be obscure glazed. You can’t swap them out for clear glass unless you get planning permission.
Any window facing a neighbour needs to be non-opening unless the lowest opening part is at least 1.7 metres above the floor. That’s to stop people peering into next door’s garden.
Side-facing windows? The rules are even tighter under permitted development. You can’t add new ones or make existing ones bigger without consent.
Privacy requirements apply to:
- Balconies and raised platforms
- Roof terraces or viewing areas
- Any external staircases
Those features aren’t permitted development, no matter the size or spot. They always need full planning permission.
Limits, Exceptions, and Article 4 Directions in London
Article 4 directions can remove permitted development rights in some areas across London. If you’re in one of these zones, you’ll need planning permission for changes that might normally be allowed.
Areas with Restricted Permitted Development Rights
London boroughs use Article 4 directions to control development in sensitive spots. Councils can set these up for whole boroughs or just certain neighbourhoods.
Conservation areas almost always have Article 4 restrictions. It’s about protecting historic buildings and the look of the area.
In places with lots of housing demand, councils often block office-to-residential conversions. They want to keep commercial space and manage housing growth.
Some boroughs try to protect family homes from being split into bedsits or HMOs (houses in multiple occupation). Residents can even push their council to adopt Article 4 directions to stop this.
High streets and business districts might restrict converting shops to flats. That way, they keep local shopping and jobs alive.
You can check your council’s Article 4 directions online. Just search your council’s name and “Article 4” for the details.
How Article 4 Directions Affect Your Project
If Article 4 directions are in place, you’ll need planning permission for certain work that would usually be permitted. It doesn’t mean you can’t do your project—it just adds another hoop to jump through.
You have to submit a full planning application for any restricted work. That means drawings, supporting documents, and paying application fees.
Expect the process to take longer. Most planning applications run 8-13 weeks before you get a decision.
Key implications for your project:
- Extra costs for fees and possibly professional help
- Longer timelines due to the formal process
- Potential refusal if your plans don’t match local policies
- Neighbour consultation is part of the process
The council will decide based on housing needs and the area’s value. They have to weigh up your plans against their own objectives.
It’s worth checking for Article 4 restrictions before you start planning. That way, you don’t waste time or money on redesigns later.
Navigating Building Regulations and Legal Certificates
Even if your project falls under permitted development, you still need to meet building regulations for safety and structure. Getting the right certificates protects your property’s value, especially if you want to sell later on.
Building Regulations Compliance
Building regulations apply to most construction work, no matter if you have permitted development rights or planning permission. These rules make sure buildings are safe and sound.
You need to submit a building regulations application before you start on extensions, loft conversions, or anything structural. The application covers structural integrity, insulation, fire safety, and drainage.
Two application routes are available:
| Application Type | Best For | Timeline |
|---|---|---|
| Full Plans | Complex projects, extensions | 5-8 weeks approval |
| Building Notice | Simple internal work | Start after 2 days |
Your local council’s Building Control team will inspect at key stages. They’ll check foundations, structural work, and do a final sign-off when you’re done.
Building control officers keep an eye on safety and quality during the build. Once everything passes, you’ll get a completion certificate.
Lawful Development Certificates
A Lawful Development Certificate (LDC) gives you legal proof that your permitted development project follows planning law. You don’t have to get one, but it’s a smart move to protect your investment.
Certificate types include:
- Proposed LDC: Confirms planned work is permitted before you start
- Existing LDC: Proves completed work is lawful
It’s wise to apply for a proposed certificate before starting anything controversial or borderline. You’ll need detailed drawings, specs, and evidence that your plans fit permitted development rules.
Local planning authorities usually take eight weeks to decide on LDCs. They have to issue the certificate unless they can show your work doesn’t qualify.
The certificate really helps if neighbours object or if planning enforcement comes knocking down the line.
Selling Your Property after Works
When you finish building work, it changes your property’s value and how easily you can sell it. Buyers and mortgage lenders want to see proof that all the construction meets regulations and planning requirements.
You need to show building regulations completion certificates for any structural work, extensions, or conversions. If you don’t have these certificates, sales can get delayed, offers might drop, or buyers may even walk away.
Essential documentation includes:
- Building regulations completion certificate
- Planning permission documents (if required)
- Lawful Development Certificate
- Warranties for materials and workmanship
If you’re missing certificates, you can apply for regularisation through your local authority. This process asks for retrospective approval and might mean invasive inspections or extra remedial work.
Understanding regulatory requirements early prevents expensive modifications and delays during construction.
Frequently Asked Questions
London homeowners often run into confusion about extension size limits, building regulations, and the difference between permitted development and planning permission. Getting your head around these things helps you manage your home improvement project more smoothly.
What are the size limitations for outbuildings under permitted development rights in London?
In London, outbuildings have to meet certain height and coverage rules under permitted development rights. Single-storey outbuildings can go up to 4 metres high if they have a dual-pitched roof, or 3 metres with any other roof.
The total area covered by all buildings can’t be more than 50% of your garden as it was in 1948 or when first built. This includes your house, existing outbuildings, and anything new you want to add.
If your outbuilding is taller than 2.5 metres, you need to keep it at least 2 metres from any boundary. If it’s closer, you have to keep the height under 2.5 metres.
Outbuildings can’t be used as separate living accommodation with sleeping, cooking, and washing facilities. That would need full planning permission, not just permitted development rights.
How do permitted development rights differ from planning permission?
Permitted development rights let you do certain types of building work without submitting a full planning application. These rights are automatic permissions set by Parliament.
Planning permission means you have to submit detailed plans to your local council. They’ll check your proposal against local policies and might consider objections from neighbours.
Permitted development has strict size and design limits, so you’ve got to follow them exactly. Planning permission gives you a bit more flexibility but usually takes longer and costs more.
If your project meets all the permitted development requirements, you can start work right away. With planning permission, you’re looking at 8-12 weeks for approval, and there’s always a chance they’ll say no.
What are the maximum dimensions for an extension without planning permission?
Single-storey rear extensions can go out 8 metres from the original house for detached homes, and 6 metres for all others. Maximum height is 4 metres, or 3 metres if you’re within 2 metres of a boundary.
Two-storey rear extensions are capped at 3 metres from the original rear wall. The extension can’t be taller than your house and you need to use matching materials.
Side return extensions can fill the space between your house and boundary, but they usually can’t go above single-storey height. If you want a multi-storey side extension, you’ll probably need planning permission.
All extensions have to stay within 50% of the land around the original house, counting any outbuildings. This is based on your property boundary as it was in 1948 or when first built.
Can you explain the General Permitted Development Order (GPDO) and its implications for property extensions?
The General Permitted Development Order gives a national grant of planning permission for certain types of building work, so you don’t need local council approval. Parliament sets these rights through national laws, not local policies.
The GPDO spells out detailed requirements for extensions, like dimensions, materials, and design. You have to follow every rule to use these automatic permissions.
Sometimes London boroughs take away permitted development rights in certain areas using Article 4 Directions. You’ll see this a lot in conservation areas, where councils want to protect the local character.
The GPDO changes from time to time, expanding or tweaking what’s allowed. Recent updates have made some extensions bigger and added things like new storeys to existing buildings.
What building regulations must be adhered to when constructing an extension under permitted development?
All extensions need Building Regulations approval, whether you use permitted development rights or get planning permission. Building Regulations cover things like structural safety, fire safety, and energy efficiency.
You’ll have to submit Building Regulations applications to your local council or an approved inspector. They’ll check your plans and visit the site at different stages of construction.
Some key areas include foundation design, wall insulation, window specs, and electrical safety. Extensions also need to meet current thermal performance standards and, where needed, accessibility rules.
Your builder should notify Building Control at stages like foundation excavation, wall construction, and completion. If you don’t get the right approvals, you might have trouble selling the property later on.
Does the use of permitted development rights affect the requirement for Building Regulations approval?
Permitted development rights and Building Regulations are completely separate requirements for extension projects. Using permitted development rights doesn’t mean you can skip Building Regulations approval.
Building Regulations set construction safety and technical standards. Permitted development deals with planning and design rules.
You’ll need to comply with both systems for any extension project. The approval processes don’t overlap and run on their own timelines.
Building Regulations approval usually takes about 5-8 weeks. Permitted development rights kick in right away if you meet all the criteria.
Some tiny projects, like a small porch or a conservatory, might not need Building Regulations approval. This exemption applies no matter if you use permitted development or get planning permission.