Do I Need Planning Permission for My Extension?

Planning permission can feel like one of the most confusing parts of extending your home — but it doesn’t have to be. Whether or not you need it depends on the size, design, and location of your extension, as well as the type of property you live in.

Here’s a simple guide to help you work out what applies to your project.

Planning permission is formal approval from your local council that allows you to carry out certain types of building work. It’s designed to make sure developments are safe, suitable for the area, and don’t impact neighbours unfairly.

Many home extensions fall under what’s known as Permitted Development Rights. This means you can build certain types of extensions without applying for planning permission — as long as your project follows a specific set of rules.

You might not need permission if:

• Your extension is at the rear of the property.
• It doesn’t exceed the height or size limits.
• Materials are similar to the existing house.
• It doesn’t face a road.
• The property isn’t in a conservation area or listed.

Rear single-storey extensions, for example, can often be built under Permitted Development — but only up to a certain size (e.g. 3m for a semi, 4m for a detached house).

You’ll likely need planning permission if:

• Your extension is larger than what’s allowed under Permitted Development.
• It’s at the front of your house or side-facing a road.
• Your home is in a conservation area, national park, or is listed.
• The design is significantly different from the existing building.
• You’ve already used up your Permitted Development allowance with previous extensions.

Every council can interpret things slightly differently, so it’s always worth checking before you commit.

That’s where we come in. At Plan My Extension, we offer simple, fixed-fee planning packages and can let you know early on whether planning permission is needed. If you do need it, we’ll prepare all the drawings and submit the application on your behalf — no jargon, no stress.

Even if your extension qualifies as Permitted Development, you can apply for a Lawful Development Certificate to confirm this in writing. It’s not required, but it’s a smart move — especially if you plan to sell your home later.

Planning permission isn’t always needed, but it’s essential to check early. With the right advice and clear drawings, the process doesn’t have to be a headache. For more information reach out to our team today.