Can I Build an Extension?
UK Planning Permission Guide
Thinking about extending your home? You may be able to build an extension without applying for full planning permission, but it depends on your property, the type of extension and the planning rules that apply.
Before spending money on architectural plans or builders, it is worth checking the planning history and restrictions affecting your property.
Check your property's extension potential with Planning Scan.
Do I Need Planning Permission for an Extension?
Not every house extension requires a full planning application.
Some extensions can be built under permitted development rights, provided they meet the relevant requirements and limitations. If your proposed extension falls outside those rules, you may need to apply for planning permission.
The requirements can depend on:
- The size of the extension
- How far the extension projects from the house
- The height of the extension
- Where it is positioned
- Whether it is single or two storeys
- Previous extensions to the property
- Whether permitted development rights have been removed
- Whether the property is in a conservation area
- Whether the building is listed
Because every property is different, checking the planning position for your particular house is important.
Can I Build an Extension Under Permitted Development?
Permitted development rights allow certain types of home improvement to be carried out without making a full planning application.
However, an extension must meet specific conditions and limitations to qualify.
Restrictions can apply to the size, height and position of an extension, as well as the amount of development that has already taken place at the property.
Certain properties and locations can also have additional restrictions.
If your proposed extension does not meet the permitted development requirements, you may need to apply for planning permission.
Can I Build a Rear Extension?
Rear extensions are one of the most common ways to add extra living space to a home.
Depending on the property and the proposed size and design, a rear extension may be possible under permitted development or may require planning permission.
Before deciding what you can build, it can be useful to check your property’s planning history and look at similar rear extensions that have been approved nearby.
Can I Build a Side Extension?
Side extensions can also be possible under permitted development in certain circumstances.
The planning requirements can be more restrictive depending on the size, height and position of the proposed extension.
Looking at previous applications on your street can provide useful local planning context, particularly if neighbouring properties have already been extended.
Can I Build a Two-Storey Extension?
Two-storey extensions can have different planning considerations from single-storey extensions.
Factors such as the height, position, distance from boundaries and relationship with neighbouring properties can all be relevant.
If you are considering a two-storey extension, researching previous applications for similar properties in your area can help you understand the local planning history.
What Could Stop Me Building an Extension?
There are several reasons why an extension may require planning permission or face additional restrictions.
Conservation Areas
Properties in conservation areas can be subject to additional planning controls. The location of your property should therefore be checked before assuming that permitted development rights apply in the usual way.
Listed Buildings
Listed buildings have additional protections. Depending on the proposed work, listed building consent and planning permission may be required.
Previous Development
Previous extensions and alterations can affect what further development is possible under permitted development rights.
Planning Restrictions
Some properties have restrictions that limit or remove permitted development rights.
Neighbouring Properties
The effect of a proposed extension on neighbouring properties can also be relevant when a planning application is assessed.
Check Your Property's Planning History
One of the best ways to research a proposed extension is to see what has already happened at your property and nearby homes.
Previous planning applications can show:
- Extensions previously proposed
- Extensions that were approved
- Applications that were refused
- Previous planning decisions
- Similar developments nearby
- Planning activity on your street
A previous approval does not guarantee that your extension will be approved, but it can provide useful local planning context.
Check Your Extension Potential
Every property is different, so what has been approved elsewhere does not automatically mean the same development will be approved at your property.
Use the Planning Scan Extension Planning Checker to investigate your address, previous planning applications, nearby extensions and relevant planning information.
Enter your address and get the planning picture for your property in seconds.