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Are you dreaming of the concrete sectional garage, but the usual permission war is slightly bothering you? Or are you planning for the garage, but don’t know how big can a building be without planning permission?
Building permissions exist in most countries and usually, there is something that defines when you need one and when you don’t. So far I’ve heard about the size and foundation types from some foreign friends.
That being said, do take this as a general guide and check your local authorities if these things hold true. The only thing you can trust is the bureau that handles these things in your country or city.
Also, as I’m a poor concrete worker, there is no legal advice. Just your regular wondering on what might or might not need a permit. So if you have building ideas you will have a bell ringing that you need to ask somewhere can you do it.
Types of garages
So you have 2 choices here. You either build your own garage walls and roof or buy a prefab garage. Both have their good sides and you have to think about what you prefer if you decide to build one.
Traditional garage building
Traditional garage, if build apart from the house, is a concrete slab and walls and roof build on top of it. What it means is that from start to finish, you measure everything, cut the pieces, and slowly build your project.
It’s a lot of work, but this way you get everything right. You’re not building from ready-made parts so there’s nothing else to miss than building materials.
An experienced builder will have no trouble building like this. For a beginner, there will be lots of question marks.
Prefab garage building
A prefab garage is a ready-made garage kit that is build of premade parts at the site. Prefab garage planning permission should not be any different from other planning permissions.
That is because you would need to build a foundation for it so it would be a new building on your property. These types of permissions are usually quite exact on when they apply and when they don’t.
Now prefab garage comes in ready parts. Some might have some structures ready to build, depends on who you buy from and how they deliver.
Some prefab garages might come in little pieces even and then you have to build it from scratch from ready-made parts. Nothing wrong with that if you have instructions and everything is there in a sensible order.
It’s a good way for beginners to build as everything is there for them, no shopping needed. Instructions tell you what to do.

How big can a garage be without planning permission
Now, finally, let us get to the part about why you are here. How big can I build a garage without planning permission?
In the UK it seems you can build 15 square meter garage or smaller without planning permission. Provided it’s not attached to the house.
You can build 30 square meters or smaller if it is attached. In the latter case, it needs to be built with non-flammable materials and you need to have a 1-meter distance from walls and fences.
In the US I don’t even try as the permits needed change from place to place and often reflect local issues. I recommend you to check from local authorities what you can and cannot do without a permit.
These minimum garage size building regs can be applied to concrete sectional garages as well I guess. The material shouldn’t matter as the size is the defining factor and placing.
Do you need planning permission to convert a garage
Another thing that might interest us is can we convert a garage without planning permission. Sometimes we just run out of living space as kids grow up and we need new solutions.
Usually, if the garage is not built larger or there is no mention in the former planning permission, you can convert it. If there is a mention that it should be a garage, you need to apply for removing that condition.
This is again the UK as they seem to have lots of information available. But, as stated before, most cities and such control buildings in a way that some sort of permissions are needed most of the time.
It doesn’t hurt to ask if something can be done. Sometimes you get the green light straight away and sometimes you might have to ask for permission.
Asking for more info doesn’t hurt
I see it this way. If you’re making changes inside your house that don’t endanger anyone in the house, they have little reason to stop you.
They don’t have anything invested and if it doesn’t change outwards appearance too much, neither does anyone else. Of course, there is always that one neighbor, but those shouldn’t have much weight in this sort of decision-making.
So if it’s a concrete, prefab, or wooden garage planning permission, check the size and see if you need one. Remember to measure your vehicles if it’s for car storage so you won’t run out of space.
7 years rule
I run into something called the planning permission 7-year rule. It seems to mean that authorities can’t do anything about buildings that would need planning permission, but were built without.
Now, this might seem nice on the paper if you can hide your changes that would need permission for 7 years. You do have to remember that these things can come back to haunt you.
Imagine if at one point you want to sell your property, but can’t get clean papers because of that. There is something that is built, but it’s without a permit. No one going to sign that.
So if you follow shortcuts, you have to think of will they come back to bite you.
Lean-to garage planning permission
I wanted to add lean-to garages here as they might seem a bit confusing. That is because they might not have a concrete base, but only pillars and some roofs over the open area. Now, what’s the deal with that?
Apparently, in the UK you can build up to 4 metres in height, 4 metres length in detached home / 3 metres in a terraced home. You can’t build it higher ground than the rear surface of your property and not on public territory.
That seems like a good area for open-air car storage. It’s good if you have winters and hate to scratch windows. The roof will stop them from freezing and you don’t have to clean your car from snow that much.
For me, that is enough for a car. I like my garages as hobby workshops.
Conclusion
You should have a sort of answer on “Do I need planning permission for a concrete sectional garage” now. You shouldn’t if you build small enough.
If it’s good for you when it’s small, then you can build one, but if you dream of bigger things maybe proceeds with one. If you get the green light you can build what you need.
If you’re wondering do I need planning permission to extend the garage you can also refer to local guidelines. My guess after reading about it would be that you do if you cross the limits that are set.
But again, I have no legal knowledge and I like to exploit those who are in deciding place at things like this. That’s why they are there.
When it comes to building, most often I like to think that I will probably sell my house someday. For that reason, I try to keep everything so that it passes inspection.
I know I can do most of the things myself, but for certain things, it’s good to have others install them. That way I can get a stamp on my paper when it’s time to shift who is responsible if a hazard happens.
Also, if you’re interested in concrete flooring, check out this guide on doing epoxy garage floors. It might serve well in your project.
Another option could be this bounce house guide, but for pavilion tent, if you wish some kind of cover for the weather, but don’t want a log cabin or garage.