Planning permission checker
Answer a few questions about your project and find out whether it falls under permitted development, needs prior approval, or needs a full planning application.
Last updated July 2026 · built by working UK builders
Permitted development, prior approval and planning permission
Permitted development is a national grant of permission for common household projects within set limits. You do not apply — you simply comply. The catch is that the limits are precise and the definitions are unforgiving, particularly the word "original", which means the house as first built or as it stood on 1 July 1948, not as you bought it.
Prior approval sits in between. Larger single-storey rear extensions — up to 6m on a terrace or semi and 8m on a detached house — are allowed, but you must notify the council first, and neighbours get 21 days to object. If they object, the council decides whether the impact is acceptable.
Planning permission is a full application: drawings, fee, consultation, typically eight weeks and often longer.
The things that quietly remove your rights
- Flats and maisonettes. No permitted development rights whatsoever.
- Listed buildings. Listed building consent for nearly everything, and unauthorised work is a criminal offence.
- Conservation areas and other designated land. Side extensions, two-storey extensions, roof extensions and cladding all come out.
- Article 4 directions. A local removal of a named right — very common in Victorian terraced streets for front windows and doors.
- Planning conditions on new estates. Developers routinely have PD rights removed as a condition of the original permission.
- Restrictive covenants in the title. Not planning law at all, but just as binding, and enforceable by whoever holds the benefit.
- Previous extensions. Your allowance is measured against the original house, so anything a previous owner built has already used some of it up.
Get a Lawful Development Certificate
If your project is permitted development, apply for a Lawful Development Certificate anyway. It costs about half a planning fee, takes roughly eight weeks, and produces a document that says the council agrees. When you come to sell, the buyer's solicitor will ask how you know the extension was lawful. "The internet said it was permitted development" is not an answer that gets a sale over the line.
Planning is not building regulations
They are separate systems and you usually need both. Planning is about appearance and impact; building regulations are about structure, fire, insulation, ventilation and drainage. A project can be entirely permitted development and still need full building regulations approval — a loft conversion is the classic example. Ourbuilding regulations checker covers that side.
Frequently asked questions
Do I need planning permission for an extension?
Many single-storey rear extensions on houses fall under permitted development — up to 3m deep for a terrace or semi, 4m for a detached, or 6m and 8m under the larger home extension prior approval scheme. But permitted development does not apply to flats, listed buildings or anything covered by an Article 4 direction, and it is heavily restricted in conservation areas.
What is a Lawful Development Certificate?
A formal confirmation from the council that your project is permitted development and did not need permission. It costs around half a full application fee and takes about eight weeks. It is not legally required — but when you sell, the buyer’s solicitor will ask how you know the work was lawful, and this is the document that answers.
What is the difference between planning permission and building regulations?
Planning controls what a building looks like and where it goes. Building regulations control whether it is safe, warm, ventilated and structurally sound. They are separate systems with separate applications, and you commonly need both, or building regulations only.
What happens if I build without permission?
The council can serve an enforcement notice requiring removal. In England the immunity period is generally ten years for unauthorised building work, though the rules changed in 2024 and pre-existing breaches may follow the old four-year rule. Unauthorised work will surface when you sell, and buyers will want indemnity or a retrospective application.
Does permitted development apply in Scotland, Wales and Northern Ireland?
Each nation has its own permitted development rules and they differ in the detail — the dimensions, the designated land restrictions and the prior approval schemes are not the same. This checker follows the England regime. Check with your own council if you are elsewhere.