Do I need planning permission for an extension?
Not always. Many single-storey rear extensions fall under permitted development, so you can build without a full planning application if you stay within the size limits. Double-storey, front and side extensions, and homes in conservation areas, usually do need planning permission. We will tell you honestly where your project stands.
Recent extension projects
What is permitted development?
Planning can feel daunting, but it does not have to be. Permitted development is a set of national rules that let you extend your home without a full planning application, as long as you stay within defined limits on size, height and position. It exists to save homeowners time and paperwork on modest, sensible projects, and many single-storey rear extensions qualify.
The limits cover things like how far an extension can project from the original rear wall, its overall height, how close it sits to boundaries, and how much of the garden it uses. The rules are different for detached, semi-detached and terraced homes. Because the detail matters, we always check your specific property rather than assume, and we can arrange a lawful development certificate to confirm your project qualifies.
When do you usually need planning permission?
Some projects fall outside permitted development and need a full planning application to your local council. As a general guide, you are likely to need planning permission in these situations.
- Double-storey and multi-storey extensions, which usually exceed permitted development limits.
- Front extensions, which almost always need permission.
- Side extensions, particularly on terraced and semi-detached homes.
- Large rear extensions that project beyond the permitted development allowance.
- Homes in conservation areas, where permitted development rights are restricted.
- Listed buildings, which need listed building consent as well.
- Flats and maisonettes, which do not have the same permitted development rights as houses.
If your project needs permission, we will help you through the application and work with your architect on the drawings. Our double-storey extension and rear and side return pages explain what to expect for those specific builds.
What about building regulations?
Building regulations are separate from planning, and almost every extension needs building regulations approval regardless of whether it needs planning permission. They make sure the work is safe and sound, covering structure, foundations, insulation, drainage, ventilation, electrics and fire safety.
Building control, either from the council or an approved inspector, checks the work at key stages and issues a completion certificate at the end. This certificate matters, because it proves the work was done properly and you will need it when you come to sell. We build to full building regulations standards and work hand in hand with building control throughout.
What is the Party Wall Act?
The Party Wall Act applies when you build on or near a shared boundary with a neighbour, for example a party wall between terraced or semi-detached homes, or foundations close to the boundary line. It is designed to protect both you and your neighbour, and it is separate from planning permission.
If the Act applies, you must give your neighbour formal notice, and they can agree or ask for a party wall surveyor to prepare an award that records the condition of their property and sets out how the work will proceed. It sounds formal, but it is routine, and we will guide you through it so relations with your neighbours stay friendly.
How we help with the whole process
We are builders, not planning consultants, but after years of extensions across North London we know the process inside out, and we make it straightforward for you. We will tell you honestly whether your project is likely to fall under permitted development or need planning permission, and we will point you to trusted architects and engineers for drawings and calculations. If you already have a professional team, we will work alongside them.
Throughout the build we work with building control, handle the technical detail, and guide you through any party wall matters. John runs the site, Marian keeps the quote clear with no hidden fees, and Dan and Niko lead the build. It is a calm, honest, joined-up service from first visit to finished job.
What our customers say.
“John and the whole crew were a pleasure to work with. Fast, great communication, finished on time and to a high quality.”
“Dan and Niko put real care into the work; Marian set everything out clearly with no hidden fees. They went above and beyond.”
“We're an architecture practice and have worked with Kev Construct for years. Reliable, trustworthy, excellent finishes.”
Good to know.
How long does planning permission take?
A householder planning application typically takes around eight weeks for the council to decide, once it is validated, though it can take longer if there are complications or objections. Permitted development projects avoid this wait, which is one of their main advantages. We will help you plan realistic timings, and where a lawful development certificate is needed, we will factor that in too.
What happens if I build without the right permission?
It is not worth the risk. If you build something that needed planning permission without it, the council can require changes or even removal, and you will struggle to sell the property without the right paperwork. Missing a building regulations completion certificate causes the same problem. We make sure everything is properly approved and signed off, so your extension is safe to keep and easy to sell.
Do I need permission to knock through into an open-plan kitchen?
You do not usually need planning permission to remove an internal wall, but you almost always need building regulations approval, because removing a load-bearing wall affects the structure. A structural engineer will specify the steel beam needed to support the floor above, and building control will inspect it. We handle this routinely as part of extension and open-plan projects.
Can you help even if I have not sorted the drawings yet?
Yes. Many homeowners come to us at the very start with only an idea, and we are happy to visit, talk it through and advise on what is realistic before any drawings exist. We can then point you to trusted architects and engineers, or work alongside your own. Getting us involved early often makes the design more practical and the eventual build smoother.
Does a conservation area mean I cannot extend?
No, it means the rules are stricter. Conservation areas have reduced permitted development rights, so more projects need planning permission, and the council will pay closer attention to how the extension looks and the materials used. Sympathetic, well-designed extensions are regularly approved in these areas. We will advise honestly on what is likely to be acceptable and build to match the character of your home.
Not sure what your
project needs?
Tell us about your extension and we'll arrange a free home visit. We'll advise honestly on the permissions you need and give you a clear, fixed price in writing - with no hidden fees.
- Honest advice on permitted development vs planning
- We work with building control and your architect
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