Planning & Permissions
Permitted development explained
What it actually allows, and where it stops applying.
Permitted development is a national grant of planning permission that lets you carry out certain building work, including many single-storey extensions, loft conversions and outbuildings, without a full planning application, provided the work stays within set limits on size, height and position. It doesn't apply to flats, and it's reduced or removed for listed buildings and some conservation areas.
Last updated 17 August 2026
Key points
- Permitted development applies to houses (dwellinghouses), not flats or maisonettes.
- Each type of work (extensions, loft conversions, outbuildings) has its own specific size and height limits.
- An Article 4 direction can remove permitted development rights on specific streets, regardless of the general rule.
- Even where permitted development applies, it's worth applying for a Lawful Development Certificate for certainty, especially before selling.
Where the rules come from
Permitted development rights are set out in the Town and Country Planning (General Permitted Development) (England) Order 2015, and cover a wide range of works, from extensions and loft conversions to outbuildings and some changes of use.
Each type of work has its own class within the order, with its own specific limits — what applies to a rear extension is different from what applies to a loft conversion or a garden outbuilding.
What commonly falls under permitted development
Single-storey rear extensions within set depth and height limits, side extensions within height and width limits, many loft conversions that don't significantly alter the roof shape from the street, and garden outbuildings like garden rooms, subject to size and position, can often be built without a full planning application.
The specific limits vary by property type — a detached house generally has more generous permitted development allowances than a terraced or semi-detached one.
Where it stops applying
Permitted development rights don't apply to flats or maisonettes at all — any extension needs a planning application. They're also removed or restricted for listed buildings, and can be reduced by an Article 4 direction on specific streets or in specific conservation areas.
If a property has already used up its permitted development allowance through a previous extension, that counts against what's available now — the limits are generally a total for the life of the house, not a fresh allowance for every project.
FAQs
Does permitted development apply to flats?
No. Permitted development rights for extensions under Class A apply to houses (dwellinghouses) only — any work to a flat or maisonette needs a planning application.
How do I know if my specific project qualifies?
Use our permitted development checker for an indicative answer on a rear or side extension, or apply to your council for a Lawful Development Certificate for a formal, legally reliable answer.
Have a question about your own project?
Related guides
More on planning & permissions
Do I need planning permission?
A plain-English starting point before you speak to anyone.
Party wall agreements: the homeowner's guide
When the Party Wall etc. Act 1996 applies, and what the process actually involves.
Do you need planning permission for a conservatory?
The general position, and why an extension is worth considering too.