ePrivacy and GPDR Cookie Consent by Cookie Consent Do you need planning permission for an extension?

Do you need planning permission for an extension?

5 min read
Oct '25 • by Heather

Quick summary

In most cases, you do not need planning permission if your extension is within certain limits: for example, rear extensions up to 3m if attached or 4m if detached, side extensions taking up less than 50% of land and width of the original house, and two-storey extensions that don't exceed 50% of the house’s width or land size. These rules mainly apply to houses, not flats, maisonettes, or listed buildings, which usually require permission. If your project exceeds these limits, or if you live in a flat or listed building, you'll need to apply for planning permission, which typically costs around £100-£206 and takes about 8 weeks.

If you are looking to extend your home, you’ve no doubt been thinking about planning permission. Namely whether or not you will need it, the rules you’ll need to follow and how much it will all cost.

Our in-house planning experts have produced this updated guide…

Do you need planning permission? Maybe not.

Whether or not you can extend your home without planning permission will depend on your permitted development rights. These rights, created by the government, allow homeowners to extend without a planning application as long as their project adheres to the following strict set of guidelines.

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