Planning Permission for Extensions: Do You Need It?

Location, location, location

The first thing to check is whether your home is a listed building, falls within a conservation area or is within a national park. If any of these refer to you then PD rights don’t apply and you will need planning permission for extensions to be built onto your home.

Some newer housing developments have also had PD rights removed, so don’t automatically assume you’re safe – although you should have been told if this is the case when you originally bought the property.

Size is everything

The most important thing to think about when working out whether you’ll require planning permission is the size of what you want to build.

A single-storey extension is the most common development allowed without permission, but there are a number of requirements to meet:

If you live in a terraced or semi-detached property you can extend out 3m from the original rear elevation or 4m if your house is detached. This limit has been increased to 6m if it’s an attached house and 8m if it’s detached as long as the work is finished by 30 May 2019, but the local authority must be notified and neighbours given the chance to view the proposals and make any objections.

The extension must not exceed more than 50 per cent of the total area of the land around the original house.

The height of the eaves must not be higher than 3m and the highest point of the roof must not be over 4m, or higher than an existing adjoining roof if this is lower.

It must not be built wider than the existing house.

For a side extension, it must be single-storey and the width must not be greater than half the width of the original house.

There are other requirements to consider so it’s certainly worth double checking with your builder or architect who should have a more thorough understanding of the rules around planning permission for extensions.

These criteria mean that on the whole, conservatories can generally be built without applying for planning permission as they’re usually within the dimensions specified above.

Transforming the existing space

Transforming an under-used space into another room is certainly something to think about if you’ve got that option, and it could be far less hassle – and much cheaper – than a proper extension.

You might be considering turning your garage into a new room. This wouldn’t require planning permission as long as you aren’t increasing the overall size of the building.

Similarly, some loft conversions can be carried out without permission. Dormer windows are allowed if they don’t sit higher than the highest part of your existing roof or extend forward of the roof plane on the principal elevation.

Blend in

Under PD rights, any extension you build should use similar materials to those used in the original house and shouldn’t stand out too obviously.

Remember, you can decorate it however you please inside, so make sure to play it safe when it comes to the external aspects if you don’t want to go through the process of getting full planning permission for extensions.

Double the trouble

Just because you want a two-storey extension doesn’t mean you automatically need planning permission, but extra criteria do apply.

You can only build a two-storey extension under PD rights if it is at the back of your house, and it cannot exceed 3m in depth or be within 7m of the rear boundary. Again, speak to your builder or local authority for extra information about planning permission for extensions.

House vs flat

If you live in a flat and want to add an extension you need planning permission, regardless of whether your proposals fulfil the rest of the criteria above.

However, if you live in a top floor flat and want to convert your loft, you may be able to do that without permission as long as you aren’t extending the roof space in any way.

Remember to double check that the roof space is yours, especially if you aren’t the freeholder of the property.