Do I need planning permission?
It depends on three things: the property you’re altering, the project you’re planning, and any constraints that apply to your address. This guide walks through each of them in plain English, so you can work out whether your project needs a full planning application or qualifies as permitted development.
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Check my property — freeThe three things that decide whether you need planning permission
Planning law for home improvements in the UK is set out in the General Permitted Development Order 2015 (GPDO) and the Town and Country Planning Act 1990. Whether you need to apply for planning permission or whether your project falls under permitted development comes down to three questions you have to answer in sequence.
1. What kind of property is it?
Most permitted development rights apply to houses — that means detached, semi-detached, terraced, and end-of-terrace. Flats and maisonettes don’t have Class A rights at all, so any external alteration to a flat requires planning permission. Listed buildings need listed building consent for all external work, regardless of size. Maisonettes above commercial premises face even tighter restrictions.
2. What exactly are you building?
Each type of project has its own rules. A rear extension follows Class A, loft conversions follow Class B, roof alterations follow Class C, porches follow Class D, outbuildings follow Class E, and so on. Each class has its own dimension limits, height limits, material requirements, and location constraints. Miss one and the project falls outside permitted development.
3. What constraints apply to your address?
Even a project that would normally be permitted development can lose those rights because of where the property sits. Conservation areas restrict Class A side extensions and cladding. Article 4 Directions can strip specific PD rights on a street-by-street basis. Areas of Outstanding Natural Beauty, National Parks, and World Heritage Sites (“designated land” under Article 2(3)) cut the dimension limits in half. Tree Preservation Orders can block anything that affects a protected tree. Flood zones restrict certain outbuilding classes.
Do I need planning permission for… (common projects)
Here’s the short answer for the most common home improvement projects, assuming an unrestricted property. Always check for constraints on your specific address before you commit.
| Project | Usually need planning permission? | Guide |
|---|---|---|
| Rear extension (single storey) | No, if within GPDO limits | Rear extension |
| Rear extension (two storey) | No, if within 3m and 7m from boundary | Rear extension |
| Loft conversion | Usually no (Class B) | Loft conversion |
| Side extension | Usually no on unrestricted land, yes in conservation areas | Side extension |
| Garden room / outbuilding | Usually no (Class E) | Outbuilding |
| Porch (under 3 m²) | No (Class D) | Porch |
| Basement excavation | Yes, always | — |
| Front extension | Yes, unless it’s a porch under 3 m² | — |
| Solar panels (roof) | Usually no (Part 14) | Solar panels |
| Fences and walls (under 2m) | No (Part 2) | Fences & walls |
| Windows & doors (replacement) | Usually no, unless listed or conservation area | Windows & doors |
| Change of use (house to flats) | Yes, always | — |
| Anything on a flat or maisonette | Yes, almost always | — |
How to know for sure at your property
A short answer based on a table is useful as a starting point, but the only way to know for certain is to check the specific constraints on your property. Here are your three options, ordered from quickest to most official.
- 1. Free online check (2 minutes). Use our free check tool. Enter your postcode, tell us what you want to build, and we’ll query the live planning constraints on your property (conservation area, Article 4, listed status, flood zone, TPO, green belt, AONB) and apply the GPDO rules. You get an instant verdict with the reasoning.
- 2. Lawful Development Certificate. Apply to your council for a Certificate of Lawful Proposed Use or Development. This is a formal application for a legally binding confirmation that your project is permitted development. It takes about 8 weeks and the fee is currently £129. We generate a free LDC application pack with supporting statement.
- 3. Pre-application advice from the council. Most councils offer a paid pre-application advice service where a planning officer reviews your proposal and gives an indicative opinion. It’s non-binding but useful for borderline cases. Fees vary by council, typically £50–£300 for a householder query.
The cost of getting it wrong
Building without planning permission when you needed it can cost you a lot more than the £258 application fee. The council can issue an enforcement notice requiring you to undo the work, and if you ignore it, the council can prosecute — unlimited fine on conviction. Even if enforcement isn’t triggered immediately, the lack of consent becomes a problem the moment you try to sell the property: the buyer’s solicitor will flag it during conveyancing, and many mortgage lenders refuse to lend against property with unlawful extensions.
For this reason, if your project is close to the permitted development limits or sits on constrained land, it’s worth confirming before you build rather than relying on a best-guess reading of the rules. We built this site specifically to make that check fast and free.
What if my project needs planning permission?
If you do need to apply, the householder planning application fee is currently £258 and the council has a statutory target of 8 weeks to decide. The biggest factor in whether your application gets approved isn’t the fee or the timeline — it’s how well your proposal has been designed around the specific constraints at your address. Approval rates vary dramatically between boroughs and project types.
Get your odds — £9
Know your approval probability before you apply
Our £9 Full Report gives you a personalised approval probability based on real recent decisions near your address, the 5 nearest comparable applications, the most common refusal reasons for your property type, and a concrete action plan. Delivered as a PDF.
Frequently asked questions
Do I need planning permission for a rear extension?
In most cases no, provided you stay within the permitted development limits: 3m depth from the rear wall for terraced and semi-detached houses (4m for detached), maximum eaves height of 3m, and overall height of 4m. Two-storey rear extensions must stay at least 7m from the rear boundary. If your property is listed, in a conservation area, or covered by an Article 4 Direction, these limits shrink or disappear.
Do I need planning permission for a loft conversion?
Usually not. Class B of the General Permitted Development Order 2015 allows up to 40 m³ of additional roof space on terraced houses, or 50 m³ on semi-detached and detached houses. The conditions are that you can’t add dormers to the front elevation, raise the ridge line, or use non-matching materials. Conservation area loft conversions with external changes almost always need full planning permission.
Do I need planning permission for a garden room?
Most garden rooms, home offices, and outbuildings are permitted development under Class E. The key limits: the building must sit behind the front elevation of the house, not exceed 2.5m in height if within 2m of a boundary (4m otherwise, with a 3m eaves cap), and total outbuilding coverage can’t exceed 50% of the garden. Crucially, an outbuilding used as a self-contained living space (sleeping, kitchen, full bathroom) loses its PD rights and needs planning permission.
Do I need planning permission for a porch?
Porches under 3 m² in floor area, 3m in height, and at least 2m from any highway are permitted development under Class D. Listed buildings always need listed building consent for porches, regardless of size. Bigger porches need a full planning application.
Do I need planning permission for solar panels?
Solar PV panels on the roof of a house are permitted development under Part 14 of the GPDO, provided they don’t project more than 0.2m beyond the roof plane and aren’t installed on a listed building. In conservation areas, panels on a roof slope facing a highway need planning permission. Standalone ground-mounted arrays have tighter restrictions.
Do I need planning permission for a driveway or hard standing?
Hard standing for a car on land within the curtilage of a house is permitted development if it uses porous materials (gravel, permeable paving, reinforced grass) or if rainwater is directed to a permeable area. Non-porous surfaces over 5 m² need planning permission because of surface water drainage concerns.
What happens if I build without planning permission when I needed it?
The council can issue an enforcement notice requiring you to stop work or undo it. If the work has been in place undisturbed for 4 years (extensions) or 10 years (changes of use) without council action, it may become immune from enforcement under the old rules. Note: the Levelling Up and Regeneration Act 2023 extended the enforcement period to 10 years for most breaches in England. Unlawful work also causes problems when selling your home, because buyers’ solicitors will flag it and mortgage lenders may refuse to lend.