Permitted Development Rights for Extensions

Extend Your Home Without Planning Permission

Many homeowners in the UK can build extensions without applying for planning permission, thanks to Permitted Development (PD) rights. However, these rights come with specific conditions and limitations.

This guide covers the key rules for different types of extensions under PD rights. Always remember that these are general guidelines - your property may have additional restrictions if it's listed, in a Conservation Area, or has had PD rights removed.

Last Updated: April 2025

This guide reflects current regulations for England as of April 2025. Rules in Wales, Scotland, and Northern Ireland may differ. Always check with your local planning authority for the most up-to-date information specific to your area.

Types of Extensions Under Permitted Development

Under PD rights, you may be able to build the following types of extensions:

Rear Extensions
Side Extensions
Two-Storey Extensions
Front Extensions

Rear Extensions

Single-storey rear extensions are the most common type of household extension under PD rights. Their permitted size depends on your house type:

House Type	Standard PD Allowance	Larger Homes Scheme
Detached house	4 meters	8 meters
Semi-detached or terraced	3 meters	6 meters

Note: The "Larger Homes Scheme" (formerly known as the "Prior Approval" or "Neighbour Consultation Scheme") requires you to notify the council, who will consult your adjoining neighbors. If they object, the council will assess if the extension would have an unacceptable impact.

Diagram showing permitted development limits for rear extensions

Diagram showing maximum rear extension depths under PD rights

Key Limitations for Rear Extensions:

Maximum height of 4 meters for single-storey extensions
If within 2 meters of a boundary, maximum eaves height of 3 meters
Cannot cover more than 50% of the land around the original house
Materials should be similar in appearance to the existing house
No verandas, balconies, or raised platforms

Practical Tip

When measuring the "original house," remember this means the house as it was first built or as it stood on July 1, 1948 (if built before this date). Any previous extensions must be counted in your "50% of land" calculation, even if they were built by previous owners.

Side Extensions

Side extensions are an excellent way to add width to your home under PD rights, often used to create wider kitchens, utility rooms, or garages.

Key Rules for Side Extensions:

Single storey only
Maximum width: no more than half the width of the original house
Maximum height: 4 meters
Maximum eaves height: 3 meters (if within 2 meters of a boundary)
Cannot be on the side that faces a highway (usually the front, but for corner plots, this would include the side road)

Diagram showing permitted development limits for side extensions

Side extension maximum width limitations under PD rights

Common Side Extension Projects:

Garage Conversion + Extension

Converting an existing garage and extending it to create a larger kitchen/family room.

Utility/WC Extension

Adding a narrow side extension for a utility room, downstairs toilet, or pantry.

New Integral Garage

Building a new garage to the side of the house under PD rights.

Common Pitfall

When calculating the "half-width" rule, measure the width of the original house, not including any previous extensions. For terraced houses, measure from the center of the party wall to the outer edge of the opposite wall.

Two-Storey Extensions

Two-storey (or first-floor over existing) extensions can also qualify for PD rights, but have stricter limitations than single-storey extensions.

Key Rules for Two-Storey Extensions:

Maximum projection beyond the rear wall: 3 meters
Minimum distance from boundary: 7 meters
Roof pitch should match the existing house
Cannot include a balcony, veranda, or raised platform
Side-facing windows above ground floor must be obscure-glazed with openings 1.7m above floor level
Must be in matching materials

Diagram showing permitted development limits for two-storey extensions

Two-storey extension rules under PD rights

Important Consideration

Two-storey extensions cannot be used on the side of a property that faces a highway. They're mainly suitable for extending to the rear, and only when your property is at least 7 meters from the rear boundary.

Popular Two-Storey Configurations:

Kitchen extension with bedroom above: Extending your kitchen/dining space with an additional bedroom or bathroom above
First-floor addition: Adding a storey above an existing single-storey element (like a garage)
Rear two-storey extension: Adding depth to both ground and first floors simultaneously

Front Extensions

Extensions to the front of properties (facing a highway) generally have the most restrictions under PD rights.

Limited PD Rights

Full extensions to the front of your house typically require planning permission. The PD rights here are limited to small additions like porches.

Porches Under PD Rights:

Maximum external floor area: 3 square meters
Maximum height: 3 meters
No part can be within 2 meters of a boundary adjacent to a highway

Diagram showing permitted development limits for porches

Porch dimensions allowed under PD rights

While full front extensions typically need planning permission, here are some options that may be possible under PD rights depending on your property's specific situation:

Potential Front PD Projects:

Bay windows: Adding or extending bay windows (as long as they project less than 1 meter)
Infilling recessed areas: Filling in recessed areas at the front that don't extend beyond the main front wall
Front extension on non-highway side: If your front doesn't face a highway (uncommon, but possible), normal side extension rules apply

Design Consideration

Even when a front extension requires planning permission, modest, well-designed additions that match the character of your property and street scene are more likely to be approved. Consider using an architect for front extensions that require planning permission.

General Restrictions for All Extensions

Regardless of the type of extension, these general restrictions apply to all extensions under Permitted Development rights:

Size Limits

Cannot cover more than 50% of the land around the original house
Maximum height limitations as detailed in each section
"Original house" means as built or as it stood on July 1, 1948

Appearance

Must use similar materials to the existing house
Roof pitch should match the existing house for two-storey extensions
No verandas, balconies, or raised platforms

Excluded Properties

Listed buildings
Properties where PD rights have been removed
Flats and maisonettes (no PD rights for extensions)

Location Restrictions

More limited PD rights in Conservation Areas
More limited PD rights in Areas of Outstanding Natural Beauty
More limited PD rights in National Parks

Building Regulations

While Permitted Development exempts you from planning permission, you will still need to comply with Building Regulations for any extension. These ensure your extension meets standards for:

Structural integrity
Fire safety
Ventilation
Energy efficiency
Electrical safety
Accessibility

You can apply for Building Regulations approval through your local authority building control department or through private approved inspectors.

Learn More About Building Regulations

Party Wall Considerations

If your extension involves building on or near a boundary with a neighbor, you may need to follow the Party Wall Act 1996 procedures. This typically involves:

Serving notice on your neighbors (usually 1-2 months before work begins)
Getting written agreement from them
Appointing a surveyor if agreement can't be reached

Party wall agreements are separate from both planning and building regulations processes.

Note

This guide focuses on England's Permitted Development rights. Regulations in Wales, Scotland, and Northern Ireland have similarities but important differences. Always check with your local planning authority for region-specific guidance.

Extension Measurements

Use our calculators to help determine if your extension qualifies under PD rights:

Extension Inspiration

A modern glass rear extension within PD limits

Side extension with perfectly matched materials

Get Confirmation

Always consider applying for a Lawful Development Certificate to confirm your extension qualifies under PD rights, especially before starting work.

Learn About LDCs

Expert Extension Advice

Maximize Your PD Rights

"Consider building to the maximum permitted height when extending to the rear. The difference between a 3m and 4m height might give you room for dramatic ceiling heights, roof lights, or feature lighting."

- Sarah Williams, Architect

Budget Wisely

"Always include a 10-15% contingency in your extension budget. Unexpected issues like poor ground conditions or drainage requirements often appear once work begins, especially with older properties."

- David Chen, Quantity Surveyor

Neighbor Relations

"Even though PD rights don't legally require neighbor consultation, taking time to discuss your plans can prevent disputes. Consider how your extension affects their sunlight, privacy, and views."

- Emma Clarke, Planning Consultant

Think About Light

"Consider roof lights, light wells, or internal glazing for extensions. Adding an extension can make existing rooms darker, but thoughtful design can actually improve natural light throughout."

- James Taylor, Interior Designer

Common PD Extension Mistakes to Avoid

Ignoring Previous Extensions

Many homeowners forget to account for extensions built by previous owners when calculating the 50% land coverage rule.

Solution: Research your property's planning history through your local authority or check old deeds and surveys.

Using Different Materials

Extensions must use materials "similar in appearance" to the existing house to qualify under PD rights.

Solution: Match bricks, roof tiles, and other visible materials as closely as possible to the original house.

Misunderstanding "Original House"

The "original house" means as first built or as it stood on July 1, 1948, not as you purchased it.

Solution: Check historical records or consult with a planning professional if you're unsure about your property's original state.

Ignoring Building Regulations

Assuming PD rights mean you don't need any approvals at all is a costly mistake.

Solution: Always apply for Building Regulations approval for your extension, even when it qualifies under PD rights.

FAQs About Extensions Under PD Rights

Can I build a two-storey rear extension under PD rights?

Yes, two-storey rear extensions can be built under PD rights, but with stricter limitations than single-storey extensions:

Maximum projection of 3 meters beyond the rear wall (compared to 4m/8m for single-storey)
Must be at least 7 meters from the rear boundary
Roof pitch must match the existing house
Materials must match the existing house
Side-facing windows above ground floor must be obscure-glazed and non-opening below 1.7m from floor level

Two-storey extensions generally have more impact on neighbors' light and privacy, which is why the rules are more restrictive.

How do I measure the "50% of land around the original house" rule?

The "50% rule" refers to the total area of land around the original house (as it was first built or as it stood on July 1, 1948) that can be covered by extensions and outbuildings.

To calculate this:

Determine the total area of your property's curtilage (the land within your property boundaries, including the house)
Subtract the footprint of the original house (not including any later extensions)
The result is the "land around the original house"
Your total extensions and outbuildings cannot cover more than 50% of this area

Remember to include ALL extensions and outbuildings in your calculation, including those built by previous owners and existing structures you plan to keep.

Can I build my extension right up to the boundary with my neighbor?

Yes, you can build right up to the boundary under PD rights, but with height restrictions:

If within 2 meters of a boundary, the maximum eaves height is restricted to 3 meters
The maximum overall height within 2 meters of a boundary is generally 4 meters for a single-storey extension

Additionally, you'll need to consider:

Party Wall Agreement: If building on or very close to a boundary, you'll likely need to follow the Party Wall Act procedures
Foundation Design: Your foundations might need to extend onto your neighbor's land, which requires their consent
Maintenance Access: Consider how you'll maintain the external wall in the future

While legally possible, building right up to a boundary can sometimes create practical issues and neighbor disputes. Consider leaving a small gap if feasible.

Do PD rights apply to flats and maisonettes?

No, flats and maisonettes do not have PD rights for extensions. Permitted Development rights for extensions only apply to houses (detached, semi-detached, and terraced).

If you own a flat or maisonette and want to extend it, you will need:

Full planning permission from your local authority
Permission from the freeholder/landlord
Potentially, agreement from other leaseholders in the building
Compliance with the terms of your lease, which may prohibit alterations

Additionally, most external alterations to flats (including adding balconies or changing windows) also require planning permission.

What is the "larger homes scheme" for rear extensions?

The "Larger Homes Scheme" (previously called the "Prior Approval" or "Neighbor Consultation Scheme") allows for larger single-storey rear extensions under PD rights:

Up to 8 meters for detached houses (instead of the standard 4 meters)
Up to 6 meters for semi-detached and terraced houses (instead of the standard 3 meters)

To use this scheme:

Submit a "prior approval" application to your local authority
The council will notify your adjoining neighbors
If neighbors object within the 21-day consultation period, the council will assess whether the extension would have an unacceptable impact on their amenity
The council will then either grant or refuse prior approval

The scheme costs a small application fee (less than a full planning application) and is designed to give neighbors a say while still simplifying the process compared to full planning permission.

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Use our interactive tools to check your permitted development rights and get started on your home improvement project with confidence.

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