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Planning Permission for Extensions

When isn’t planning permission required?

Planning permission may not be required for your extension if the changes you are making are within the rules of permitted development.

If you’re not in a conservation area, don’t have a listed building or you’re not in an area of outstanding natural beauty then you probably have permitted development and as long as your house is quite original and unmodified, then you’re allowed to make various minor changes to your house without planning permission. However, you should still submit it and get a certificate of lawfulness.

Most things actually require planning permission and we would suggest that you always submit to get planning permission or a certificate of lawfulness. The reason for this is if you start building something, then typically your neighbors will inform the local authority. This happens very, very frequently – you’d be surprised. A lot of neighbors think it’s their civic duty to do this and then, you’ll have an issue with the enforcement team in the local authority.

Even if you think it’s permitted development and you don’t submit to get the certificate of lawfulness, again your neighbors will see you building something and think you don’t have planning permission because they’ll go online to see if you’ve got planning approval.

So you may well be permitted to build your extension, but unless there’s any record on the council’s website, then the enforcement team will be called. They won’t know whether it’s permitted development or not, and will request that you either put in a planning application or certificate of lawfulness.

Permitted development on a single storey extension is six meters from the original rear of the house if it's a terraced or semi-detached property (3-6 meter extensions are subject to the Neighbour Consultation Scheme)

What single storey extensions are exempt from planning permission?

Permitted development covers a rear single storey extension as long as the extension does not extend beyond the rear wall of the original house by more than eight metres if it’s a detached property or no more than six metres for any other house. However, larger single-storey rear extensions are subject to the Neighbour Consultation Scheme. This means that for a single-storey rear extension between 4-8 metres for a detached house or 3-6 metres for a semi-detached/terraced house, your Local Planning Authority will need to be informed of the proposed work via a ‘Prior Approval’ application and your extension is subject to approval.

You can also add a side extension up to half the width of the original house under permitted development.

What multiple storey extensions are exempt from planning permission?

Under permitted development, you can add a double storey rear extension on a semi-detached property of up to three meters on the ground floor and up to three meters on the first floor, but all of the extensions need to be two meters away from each boundary. If they’re touching any other extensions, then they probably won’t be covered by permitted development.

We would suggest that you need to seek planning permission on this, but you can achieve a first floor rear extension on a semi-detached property or even a terraced property under permitted development. A terraced property does tend to be a bit narrower though so it is more difficult.

For a double rear extension on a detached property, you can do up to three meters on the ground floor and up to three meters on the first floor. If you were just doing the ground floor, you could go up to four meters, but if you’re doing the double, it’s three and three.

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Do conservatories require planning permission?

Conservatories still need planning permission, but you can also do them under permitted development. They need to accord with the same rules of three meters maximum on a semi-detached, and there’s also a height restriction of three meters across all permitted development rear extensions.

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Does a summer house/granny annex require planning permission?

A summer house/granny annex can be achieved under permitted development and they can be quite a generous size in the rear garden. You could also build a pool house or a hobby room under permitted development. However, the installation of toilets and kitchens isn’t necessarily covered by permitted development so if it’s to be a self contained unit, then you may need to get planning permission.

Additionally, local authorities are always mindful that a self-contained building could be a separate dwelling and that would be unlawful and would not achieve planning approval or permitted development. If it’s ancillary to the use of the house, then that’s a different story. It’s a fine line of does it have a kitchen and a bathroom – if it doesn’t have a kitchen that it’s definitely ancillary to the house. But what the council’s looking to avoid is the homeowner potentially renting the building out as a separate dwelling.

Do I need planning permission for a garage?

Yes, it’s a structure that will either be in front of your house, beside the house or to the rear of the house. It will affect your property, your neighbors and the wider community so planning permission will be required.


If you have any questions about whether you need to apply for a certificate of lawfulness (if the work’s covered by permitted development) or you need to apply for planning permission, go ahead and book a free call below with Yoop.


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