So, you’ve got a big home improvement idea, you’ve got a builder, and you’ve got the budget. But have got planning permission?
Well, the good news is that you may not actually need formal permission. You can now do many extensions, conversions and renovations under permitted development laws instead.
Sound promising? Then let’s quickly go through these laws and see if they could help you.
What are permitted development laws?
Basically, they’re a way to shorten the sometimes costly and time-consuming planning process.
They allow you to improve or extend your home if:
- the work meets certain standards
- your home isn’t extended beyond certain size limits.
In other words, they’re there for when full planning would be, in the words of the government website, ‘out of proportion with the impact of the works carried out.’
The result? You could be admiring your newly improved home sooner with an even bigger smile across your face.
What standards do you need to meet?
The precise standards are decided by parliament, rather than your local authority, so they vary slightly in England, Scotland, Wales, and Northern Ireland.
But the general idea is to protect the neighbourhood, local amenity, and the character of your area. This means your improvements must be in keeping with the rest your street.
What’s more, your project can’t impact your neighbour’s home. For example, you can’t build anything that blocks all their light or invades their privacy.
Other things you can’t do include:
- breaking party wall agreements
- ignoring tree preservation orders
- breaching restrictive covenants.
Your building work also needs to follow building regulations, which make sure homes are safe and built to a good standard.
Are there any other restrictions?
You could find that permitted development restrictions are stricter if you live in:
- a listed building
- a new build (some have their permitted development rights removed)
- a conservation area
- national park
- an Area of Outstanding Natural Beauty
- a World Heritage Site.
What’s more, you can’t do any work under permitted development laws if you live in a flat or maisonette. Sorry!
You’ve also got to be careful if your home’s been altered under permitted development laws before. All alterations since 1 July 1948 (added together) can’t go beyond the limits, even if some of the work was done by previous owners.
How much can I extend my home by then?
Luckily, the limits allow you to do quite a lot. But it depends on what you’re building. Here’s a quick summary of the rules in March 2025.
Just skip down to the type of project you’re interested in. And remember to check with your local planning authority (in case the rules have changed) before your builder starts work.
Rear extensions (single storey)
- You can extend up to 3 metres if you’ve got a semi-detached or terraced house.
- This goes up to 4m for detached houses.
- Your extension can’t be wider than your original home.
- It can’t be higher than 4m (or 3m if the roof falls within 2m of your neighbours).
You can’t extend closer than 7m from your rear boundary.
2-storey extensions
- You can only build these at the rear of your home (not the side or front).
- You can extend 3m for semi-detached or terraced houses, 4m for detached houses.
- Your new roof ridge and eaves can’t be higher than your original roof.
- The extension can’t take up more than half the land around your house.
It must be less than half the width of your original home.
Side extensions
- Your extension must be single storey.
- Less than half the size of the original house.
- Less than half the width.
- No higher than the original roof.
Less than 4m in height (3m if it’s within 2m of your boundary).
Loft conversions
- You can’t put in a balcony or veranda (except some Juliette balconies).
- There are lots of rules about windows e.g. glass sometimes needs be frosted.
- You can’t extend the space higher than the highest point of the original roof.
- The total increase in roof volume can’t exceed 50m2 for detached or semi-detached houses or 40m2 for a terrace.
Loft staircases must have head height clearance of at least 2m.
Garage conversions
- Your garage is attached to your home.
- Most of the work must be internal.
- You can’t turn your garage into a separate dwelling.
- You can’t increase the building’s footprint.
Building materials must be similar to your original home.
Front extensions and porches
- Only porches are allowed.
- You can’t extend past the front line of your main elevation.
- Your porch can’t be more than 3m2 in size or 3m high.
It must be at least 2m back from your front boundary and the road.
Know your limits
If you’d like to know more, and fancy digging deeper into all the regulations, you can read more about the rules in England, Scotland, Wales and Northern Ireland on your government website.
Remember, it’s really important to follow the rules. Improvements that break them could land you a big fine. Or, worse still, you might be forced to knock your improvements down.
That means you wouldn’t be able to enjoy your breathtaking back room or lavish loft conversion for long. And you wouldn’t be able to remortgage, move on and make a tidy profit, either.
Because of this, it’s often a good idea to hire a surveyor or architect. You could also apply for a Lawful Development Certificate (LDC). This confirms your project is legal. And it could be helpful when it’s time to sell your home.
Permitted development laws are there to make life simpler. But things could get complicated if you push your luck.
This content was accurate when published on 07/01/2026.
If you’re interested in improving your home, check out My Home Manager in our Mobile Banking app. You’ll find helpful guides on everything from extensions to loft conversions. Need help funding your project? You could always consider a home improvement loan. Credit is subject to status.