Permitted Development Guide and Process

Permitted development rights are a national grant of planning permission for specified types of work. Where every relevant condition and limitation is met, a separate planning application may not be required. The rules are detailed, property-specific and easy to misapply, so “permitted development” should be demonstrated rather than assumed.

This guide explains the usual householder permitted development checks and process in England, including prior approval and lawful development certificates. It is general information rather than project-specific planning or legal advice.

What is permitted development?

The Town and Country Planning (General Permitted Development) (England) Order 2015, as amended, grants planning permission for defined classes of development. Householder rights can cover certain extensions, roof alterations and outbuildings, but only where the proposal and property satisfy all applicable rules.

Permitted development does not mean unregulated development. Building Regulations, structural design, Party Wall matters, listed-building controls, protected trees, restrictive covenants and other legal requirements can still apply.

When permitted development rights may not apply

Do not rely on standard extension measurements until the property’s status has been checked. Rights may be limited or unavailable where:

• The property is a flat, maisonette or another building rather than a house.
• The house was created through certain permitted-development changes of use or new-dwelling rights.
• A planning condition removed permitted development rights.
• An Article 4 direction removes a particular right in the area.
• The site is in a conservation area or other protected land where additional restrictions apply.
• The building is listed or the work affects its special interest or setting.
• Earlier extensions or outbuildings have already used part of the permitted allowance.
• The proposed use is not genuinely incidental to the house.

Greater Cambridge Shared Planning’s restriction map can identify conservation areas, listed buildings, Green Belt, protected trees and Article 4 directions for Cambridge City and South Cambridgeshire. The property’s decision notices and planning history should also be checked.

Understand the “original house”

Many permitted development measurements are taken from the “original house”: the house as it stood on 1 July 1948, or as first built if it was constructed after that date. A previous owner’s extension can therefore reduce the amount available now, even if it is not obvious from current plans.

The rules can also assess an existing and proposed enlargement together. A new part should not be judged in isolation from earlier additions.

Common householder examples

The examples below are useful screening points, not a complete eligibility test. Check the current Order and official technical guidance against measured drawings.

Single-storey rear extensions

Under the standard Class A limits, a single-storey rear extension can extend up to four metres from the original rear wall of a detached house or three metres for another house, subject to all other conditions. The total height cannot exceed four metres. If an extension is within two metres of a boundary, its eaves cannot exceed three metres.

A larger single-storey rear extension may reach up to eight metres for a detached house or six metres for another house where the larger-home-extension prior approval process is available. This route is not available on certain protected land or sites, and all the other permitted development rules still apply.

Side extensions

A side extension relying on Class A must be single storey, no more than four metres high and no wider than half the width of the original house. Additional restrictions apply on designated land. A proposal extending forward of the principal elevation, or a side elevation that fronts a highway, will normally fall outside the right.

Extensions of more than one storey

A rear extension of more than one storey is subject to tighter limits, including a maximum three-metre projection from the original rear wall and separation from the rear boundary. Upper-floor side windows must meet obscure-glazing and opening restrictions. Side extensions of more than one storey require householder planning permission.

Loft and roof alterations

Certain roof enlargements may be permitted subject to volume, height, position, materials and window conditions. Common maximum additional roof-space allowances are 40 cubic metres for a terraced house and 50 cubic metres for a detached or semi-detached house, including relevant earlier roof additions. A roof enlargement cannot simply be assumed lawful because it stays within the volume allowance.

Outbuildings

Certain single-storey buildings within the curtilage of a house can be permitted when they are for a purpose incidental to enjoying the house and meet limits on siting, height and total land coverage. Separate living accommodation, a new dwelling or primary residential accommodation is not automatically authorised as an incidental outbuilding.

The permitted development process

1. Define and measure the proposal

Prepare accurate existing and proposed drawings. Record the extension’s projection, width, eaves and ridge height, distance from boundaries, roof alterations and proposed materials. Rules of thumb are not enough where a few centimetres can change the planning route.

2. Confirm the building and land status

Establish that the property is a qualifying house and identify its curtilage. Check whether it is listed, within a conservation area or other designated land, affected by a Site of Special Scientific Interest, or subject to another relevant designation.

3. Research the planning history and local restrictions

Review previous approvals and conditions, including permissions issued when the house was built. Check for an Article 4 direction and compare historic plans or evidence to establish the original house and cumulative additions.

4. Test every condition and limitation

Assess the complete proposal against the current permitted development class. Check coverage of the original curtilage, position relative to principal and highway-facing elevations, height and eaves, boundaries, materials, windows and exclusions such as balconies or raised platforms.

5. Identify whether prior approval is required

Some permitted development rights require an application to the local planning authority before work begins. Prior approval allows the authority to assess only the matters specified for that right. It is not the same as a full planning application, and it does not remove the need to comply with every other limitation.

6. Use the larger-home-extension process correctly

For a qualifying larger single-storey rear extension, the local planning authority notifies adjoining neighbours and considers the impact on their amenity if an objection is made. The statutory determination period is 42 days from a valid notification. Work must not start until the authority confirms that prior approval is not required, grants prior approval, or the statutory period passes without a decision, subject to the exact legal procedure.

A “prior approval not required” notice does not confirm compliance with every Class A rule. The dimensions, property status and all other conditions still need to be correct.

7. Consider a proposed lawful development certificate

A proposed lawful development certificate is a formal decision that the precisely described work would be lawful for planning purposes at the date of the application. It is not always mandatory, but it can provide valuable evidence for the build, future sale, remortgage and property records.

The applicant must provide clear plans and enough factual and legal information for the authority to decide the question. Planning merits are not assessed: the question is whether the specified proposal would be lawful.

8. Complete the other approvals

Confirm the Building Regulations route, structural calculations, Party Wall position, sewer or utility consents, freeholder approval and any ecological or tree requirements. Permitted development is only a planning route.

9. Build exactly to the accepted or certified drawings

Changes in height, projection, window position, roof form or use can take work outside the permitted right or certificate. Review proposed variations before they are built and keep the decision, certificate, drawings, calculations, inspection records and completion information together.

Permitted development, prior approval and a lawful development certificate

• Permitted development is the national planning permission granted by legislation when the proposal meets its conditions and limitations.
• Prior approval is an advance application required by particular permitted development rights so the authority can consider specified impacts.
• A lawful development certificate is formal evidence that a precisely described existing or proposed development is lawful for planning purposes.

One does not automatically replace another. A larger home extension can require prior approval and must also comply with the underlying permitted development rules; a lawful development certificate may then provide additional formal evidence.

Planning permission may be the better route

Permitted development is not necessarily the best design brief. A householder planning application may allow a proposal better suited to the property, even if it falls outside permitted development limits. Compare design quality, internal layout, cost, neighbour impact and planning prospects rather than forcing every project inside a numerical allowance.

See our separate Planning Permission Guide and Process for the full application route.

Before asking a builder to price permitted development work

• Provide measured existing and proposed drawings.
• Provide the prior approval notice or lawful development certificate where applicable.
• Identify the planning evidence used to establish the original house.
• Provide Building Regulations drawings and structural calculations when available.
• Confirm who is responsible for every remaining approval and specialist design.

Use our builder’s quotation guide to compare scope, exclusions, allowances and responsibilities consistently.

How Prestige fits into the process

Prestige can use confirmed planning information and current drawings to turn the proposal into a clear construction scope and itemised quotation. We do not assume a project is permitted development because it is described that way; the customer or appointed planning professional remains responsible for confirming the lawful route unless our written quotation expressly includes that service.

What we need to quote

• Property address and brief
• Current drawings
• Planning, prior-approval or lawful-development documents
• Preferred start window and budget range

Request a Quote and upload any plans, prior approval notice or lawful development certificate available.

Frequently asked questions

Do I need to tell the council about permitted development?

Not always. Some rights can be exercised without prior contact, while others require prior approval or notification. A proposed lawful development certificate can provide formal confirmation even where it is not compulsory.

Does a neighbour objection stop permitted development?

Ordinary permitted development is a legal test rather than a neighbour vote. Under the larger-home-extension process, adjoining neighbours are consulted and the authority considers amenity if an objection is received.

Can permitted development be used in a conservation area?

Some rights remain but additional restrictions apply, and local Article 4 directions can remove particular rights. Check the exact property and proposal rather than assuming all work is prohibited or permitted.

Do permitted development extensions need Building Regulations approval?

They commonly do. Planning and Building Regulations for extensions are separate, and a lawful planning route does not confirm structural safety, insulation, fire safety, drainage or other compliance requirements.

Is a lawful development certificate worth obtaining?

It is often useful where substantial building work is proposed or future evidence may be important. The decision should reflect the project, risk and advice from the appointed planning professional.

Official permitted development resources

• GOV.UK: permitted development rights for householders technical guidance
• GOV.UK: when planning permission is required
• GOV.UK: lawful development certificates
• Greater Cambridge planning restrictions map
• Planning Portal: extension limits and conditions

More on planning, costs and contracts in our building guides.

Last reviewed: 30 August 2026. This guide applies to England. Permitted development legislation and local restrictions can change; check the current official guidance and obtain appropriate professional advice before relying on a right or starting work.