If you happen to be thinking about expanding your place a bit – for another bedroom, a bigger kitchen, or just for breathing space – you’ve likely been considering a pretty essential question: what is the maximum amount of extension that I can do on my house without planning? It is a fair thing to worry about, particularly in the UK where planning regulations may at times seem like one big maze.
The silver lining is that yes, there are plenty of homeowners who can indeed extend their homes without having to go through the entire planning permission – all thanks to permitted development rights. However, these rights also entail their sets of conditions and limitations where you need to be well conversant with before going out to make any plans.
Understanding Extension Limits Without Planning Permission
There are many home improvements in the UK that don’t demand a full planning application. You might not have to apply for planning permission if your extension matches the criteria outlined for permitted development rights.
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It is important to realise, though, that these allowances are not perfect for everyone. Factors like the kind of property you have, its surroundings, and the layout of your extension play a role in what you can build.
Whether or not you can extend your house without planning permission is based on how close your plans are to the requirements set by the GPDO.
What Are Permitted Development Rights for Extensions?
Permitted development rights are basically a set of rules that let homeowners do some types of projects on their property without having to get planning permission first. These rights allow you to make many changes around your home, like building up in the loft, adding a porch, putting up a shed, or even building an extension.
For a single-storey rear extension, current rules say homeowners can build an extra space out back as long as it does not go past four metres for detached houses, eight metres for semi-detached or terraced houses, or six metres in a conservation area.
- 6 metres for a semi-detached or terraced house.
- 8 metres for a detached house.
It must be noted that you need to get approval from the council in advance if your building design goes above 4 metres (for semi-detached or terraced) or 3 metres (detached). This is to make sure nearby neighbours get informed and that the extension doesn’t cause any problems for them.
Permitted development doesn’t apply if your property is a flat or a shared house, or if it’s in a special place like a Conservation Area, a National Park, or in an Area of Outstanding Natural Beauty. In these cases, you usually need to get full planning permission before you can start building or changing anything on the property.
Rear Extension Rules for Detached and Semi-Detached Houses
The size that a rear extension can have varies depending on what kind of property it is. Detached properties are allowed more flexibility with development.
- Detached houses may be extended by a maximum of 8 metres to the rear.
- Semi-detached and terraced houses have additions up to 6 metres to the back.
The limits only cover single-storey extensions. You are only allowed to extend a two-storey rear extension to 3 metres beyond the rear wall of the original house. For this type of work, it is usually necessary to get full planning permission.
Moreover, the extension should never occupy more than half of the land that existed around the house when it was built (or in 1948). This means any sheds or outbuildings you have as well as other extensions.
Side and Wrap-Around Extensions: What’s Allowed?
Side extensions are a usual choice for expanding properties located at the end of a terrace or next to a semi-detached house. As long as it follows these conditions, you have the right to build a side extension under permitted development.
- No more than 4 meters high
- No more than half of the original house’s width
Combining rear and side extensions into an L shape often makes the whole project larger and more difficult, so it may not be possible under permitted development rules. You usually have to get planning permission for these extensions when they make big changes to the home or have an impact on nearby buildings.
This means, if you’re wondering how big of an addition I can make in a wrap-around style without needing planning, the answer is very small. You should expect that your local authority will require full planning approval for this type of project.
Height and Roofline Restrictions to Keep in Mind
How high a property can be is one of the main things that matters in permitted development. The highest allowed height for single-storey extensions is 4 metres. Where an extension is within 2 metres of a boundary, the highest point of the eaves must be no more than 3 metres off the ground.
If you extend your house upward with a second level, both the roof slope and maximum height have to be the same as those of your current house. If your extension grows past the front or highway side of your home, you will need permission from the planning office. The restrictions exist to help ensure that the extension fits well with the existing properties nearby. Plants help you settle arguments with your neighbours.
When You Need Prior Approval Even Without Full Planning
Even if a proposed project fits the allowed development, some still ought to get permission from the local council. Because of this, you need to tell your council and neighbors before building a big single-storey rear extension.
Once you submit well-developed plans, you receive notice that you can start the extension without going through full planning permission. You won’t need as long or as many details for a spot application, but a certain type of extension does require you to take this step.
If you begin the project without required permission, the authority may take action against you and make you take it apart—therefore, you should find out from the local authority what’s needed beforehand.
