Understanding Planning Permission and Extensions

When it comes to house extensions, a lot of people don’t think they’re going to need planning permission. It’s just building on your home so it’s okay, right? Well, usually this is the case, but there are still rules and regulations you need to know about. Find out if you need planning permission on your extension or if you’ve got the green light to go ahead

Single-Story House Extensions

If you’re planning on building a single-story house extension without planning permission, you might want to check these guidelines first. You’ll be fine if your extension extends no further than three metres on a semi-detached on terraced home, and four metres for a fully detached house.

However, you can’t go three metres above ground level for your eaves, and the roof of your extension shouldn’t be higher than four metres (or higher than your houses roof if it’s lower than this). You’re also going to need planning permission if your extension is going to be wider than the existing property, or the depth is more than six metres (semi-detached and terraced) or eight metres (detached). However, this depth will need approval from your neighbours and your design proposals should still be sent to your local council.

You should also be aware that all extensions to your property collectively, including sheds and outhouses, shouldn’t cover more than half of the land outside your house.

Two-Story House Extensions

For two-story house extensions, there are definite rules you need to follow. Your extension must be no more than two metres within a boundary, and no more than seven metres of an opposite boundary. You’ll also need to apply for planning permission if your home extension goes beyond three metres of both floors of the existing property.


If you’re planning an extension to your home porch, you’re going to have to apply for planning permission for designs that are larger than three metres squared. You can’t build your porch to be higher than three metres and you need to stay two metres within your boundary.

Permitted Development Rights

If your home lies within a conservation area, a national park or is a listed property, unfortunately none of the Permitted Developments rights above will stand. This is the case for some more recent housing estates too, so be sure to find out if your property has the usual Permitted Development rights or not.

By using one of our Bluelime Home Design architects, we can make sure your extension remains within all the strict Planning Development rights and will help you get all the planning permission you need. It’s a lot less stressful with our team! We provide a number of extension services, so be sure to check them all out.

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