Do you need planning permission for an extension?

If you're thinking about planning permission, you will also need to consider building regulation standards. As with planning, there are guidelines for what can be done without the need to apply for approval.

At Everest, we have an expert team that manages planning permission for you and we've created a guide for what you can and can't do when building an extension.

This guide has been updated to include the new Building Regulations Part O and Part F 2022.

Do you need planning permission for an extension? (Updated for 2023)

The short answer is that you DON'T need planning permission for an extension if you build within your permitted development rights.

Most of the restrictions that don't fall under permitted development are for work to the front of a house, next to a road or near a boundary.

You DO need planning permission for an extension if:

All extensions:

• More than half the land around the 'original house' is to be covered (this includes any other buildings)
• The extension is forward of the front or side of the 'original house' that faces onto a highway
• Materials used are not similar to the existing house (not applicable for conservatories)

1. Higher than the highest point of the roof
2. The eaves and ridge height are higher than the existing house (single-storey and two-storey)
3. The eaves height is more than 3 metres, if within 2 metres of the boundary.
4. Addition of verandas, balconies or raised platforms

Side extensions:

1. More than single-storey or over 4 metres
2. Wider than half the width of the 'original house'

Building regulation approval is required on any work.

You MAY need permission if you live in a listed building, designated area or fall under an Article 4 Direction.

Rear extension single-storey:

1. Extends beyond the rear of the 'original house' by over 6 metres (semi) or 8 metres* (detached house)
2. More than 4 metres in height

Rear extension two-storey:

1. Extends beyond the rear of the 'original house' by over 3 metres or...
2. ...is within 7 metres of boundary opposite rear wall
3. Side-facing windows are not obscure-glazed and can open (unless the opening part is 1.7 metres from the floor of the room)
4. Roof pitch does not match existing house

*If the development is between four and eight metres to the rear of the property, then you must adhere to the neighbour consultation scheme and you have to contact your local planning office.

Conservatories, orangeries and bay windows are all treated as extensions for planning permission purposes:

Do I need planning permission for a conservatory?
Do I need planning permission for an Orangery?
Do I need planning permission for a bay window?

What is The Party Wall Act?

In addition to building regulations, you also need to know about the Party Wall Act 1996. The act is mainly to avoid disputes between neighbours and to help find resolve between two parties.

Under the Act, you're required to give notice to a neighbour in the following situations:

• If you're building or excavating on, or near to the boundary of a neighbour
• If you're working on a wall that separates your property from your neighbours

You do need to adhere to the Act separate to planning permission and building regulations. We recommend reading about the Party Wall Act here.

What is the neighbour consultation scheme?

In May 2019, the government made permanent the temporary rules for the size of extension that you can build under permitted rights.

If building a single-storey extension of more than four metres up to eight metres from the back of your house (for a detached house, six metres for semi-detached) you have a duty to inform your neighbour. Known as the neighbour consultation scheme.

Halfway between permitted rights and planning permission, the neighbour consultation scheme is a way to keep control of the bigger developments and avoid neighbour disputes.

Instead of speaking to your neighbour directly, you must contact the local planning office and they consult with your neighbours about your development. If your neighbour objects with a fair reason, the planning office can stop your permitted development.

Note, this is only for large extensions over four metres and you can still build up to four metres without having to go through this process.

If you're thinking of adding roof lights or adding new windows to your extension read about when you need planning permission and building regulations for windows here.

More information

• Read a more detailed explanation on the technicalities of permitted development rights for householders here.
• Read more information about building regulations here.
• The information provided above is taken from government guidelines at from the Planning Portal and Gov.uk and is a guide only and is not a source of legal information.

Information is correct at time of publication: Updated January 2023.

Planning rules are subject to change. Always seek approval from your local planning authority before starting any building work.

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