Do I need planning permission for my extension?

The short answer is – not necessarily. There are in fact a number of different building works that you can carry out without needing planning permission. You can, in fact, build quite a lot without needing it. Mainly projects fall under “permitted development rights”.

What are Permitted Development Rights?

This is a general planning permission given by Parliament, which means that you don’t need to apply for planning permission.

There are some limits to this, however. For example, if you live in:

• a Conservation Area
• a National Park
• an Area of Outstanding Natural Beauty
• a World Heritage Site or
• the Norfolk or Suffolk Broads
• A listed building.

Then your permitted development rights are different.

Single Storey Extensions

Surprisingly, you can build a single storey extension without planning permission, as long as you adhere to a set of caveats. Under Permitted Development, you can build a single storey extension as long as:

• The extension does not sit forward of the principal elevation
• The materials are similar
• The eaves aren’t higher than 3m, and no more than 4m in height otherwise (if it is within 2m of any boundary)
• It’s no more than 4m in depth (detached house) or 3m in depth (semi-detached or terrace) (for rear extensions)
• The width of the extension is not be greater than half the width of the original dwelling (for side extensions). Side extensions are not permitted on Article 1(5) Land (e.g. AONB, Conservation Areas)

There are more caveats that you should familiarize yourself with before you go ahead with your project. You can find them on the planning portal website.

These restrictions also apply for conservatories and orangeries.

Two Storey Extensions

Two storey extensions are often more efficient than building a single storey extension, and they can often completely transform the way that you use your home.

You can build a two-storey extension under Permitted Development, but more often than not you will need planning permission.

Planning permission will be required if:

• The extension covers more than half the area of land surrounding your home
• It extends towards a road
• It increases the overall height of the building
• It extends more than 6m from the rear of an attached house
• It extends more than 8m from the rear of a detached house
• It is taller than 4m
• It is more than half the width of your house
• It uses different materials to those of the original house
• includes a balcony or raised veranda

You may also have to consider the party wall act if your extension includes a boundary wall.

Generally, you should get in touch with your local planning authority and discuss your plans before any work begins. A qualified surveyor should also have a good idea of what falls under planning permission.