How Big Can a Garage Be Without Planning Permission

In the UK, many garages can be built without planning permission under what's known as permitted development rights. These rights allow homeowners to make minor changes or additions to their property without needing full planning approval. But to avoid needing permission, the garage must follow strict rules on size, height, and placement.

So, how big can a garage be without planning permission? If it’s a detached garage, it must be no taller than 4 metres with a pitched roof, or 3 metres for any other roof type. If it’s within 2 metres of a boundary, the maximum height is reduced to 2.5 metres. The structure must be single-storey and not cover more than 50% of the total land around the original house. The floor area also needs to stay within reasonable domestic use — typically under 30 square metres to avoid Building Regulations in some cases, though that doesn’t replace the need to meet planning rules.

Size is one of the most important factors in whether your garage needs planning permission. It’s not just about the footprint but also the overall height and how much space the structure takes up compared to the rest of the land around your house.

If you go too big — either in terms of square footage or height — the garage may no longer qualify as permitted development. A common mistake is assuming that just because the garage is for personal use, the size doesn’t matter. But if it dominates the garden or exceeds height limits, the council may see it as an overdevelopment, triggering a formal planning process.

Even if the garage fits the limits, anything that looks overly large or out of proportion for your property might draw attention — especially if neighbours raise concerns.

Where you place your garage can be just as important as how big it is. Under permitted development, the garage must not be forward of the principal elevation — that means it can’t be in front of your house or between the house and the main road. This rule protects the look of neighbourhoods and streets.

If your garage is within 2 metres of a boundary, the maximum height drops to 2.5 metres regardless of the roof type. That rule exists to prevent overbearing structures right up against neighbouring fences or walls.

In conservation areas, National Parks, or if your home is listed, even small garages might need planning permission depending on visibility and impact. And if your property has had previous extensions or additions, you’ll need to make sure your garage doesn’t push you over the total allowable development limit.

So while size is critical, location can make or break whether you need to submit a planning application.

Many homeowners think it’s just about square metres, but the reality is more layered. When we ask “how big can a garage be without planning permission?”, we’re really talking about a combination of size, height, location, and intended use. You could build a relatively large garage and stay within the rules, or a small one that still needs permission if it's in the wrong spot.

What catches a lot of people out is the 50% rule. You can’t cover more than half the land around the original house with outbuildings — that includes all extensions, sheds, summer houses, and the garage itself. If your garden’s already busy with other structures, even a modest garage could push you over the line.

Then there’s the height trap. If the garage is near a boundary — and “near” means within two metres — your height limit shrinks to just 2.5 metres, no matter the roof type. That’s lower than most people expect, and it can rule out pitched roofs or overhead storage without needing planning.

Even if you stay within the rules, it’s not always black and white. Councils still have the right to step in if they believe your garage will have a negative visual or environmental impact, particularly in densely built-up areas, conservation zones, or if the garage is visible from the road and looks oversized. You don’t have to be breaking the law to get a visit from the planning office — just raising eyebrows can be enough.

Also, don’t forget Building Regulations. Planning permission and building control are separate. Even if you don’t need permission, you might still need to meet structural, fire safety, drainage, and electrics standards — especially if your garage is over 30 square metres or attached to the house.

Another factor is usage creep. A garage intended for parking or storage that slowly evolves into a gym, studio, office, or sleepover spot might start off fine but cross into planning territory if it changes how the space is used long-term. Councils pay attention to how outbuildings are actually being used — not just what you say on day one.

Bottom line: planning permission isn’t always needed, but that doesn’t mean it’s hands-off. Getting your garage size and setup right from the start saves you from retroactive approvals, disputes with neighbours, or costly rebuilds if something goes wrong.