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Do I need planning permission?

Pick your project, type in the sizes and see whether it is likely to be permitted development, needs prior approval, or needs a planning application. You get the reasons behind the answer and what to do next. These are the national rules for houses in England, and your council has the final say.

Red-brick rear single-storey extension with bi-fold doors beside a neighbour's fence

Measure from the back wall of the house as first built (or as it stood on 1 July 1948) to the outer face of the new wall.

If the new part joins an earlier extension, the two count together. Enter 0 if there is none.

Where the lowest part of the roof meets the outside wall, measured from the ground.

For a fence, wall or gate, also say yes if it forms a boundary with a neighbouring listed building.

Your result

Verdict

Likely permitted development (no application needed)

Application route
No planning application needed
Main reason
Sticks out 3 m, within the 3 m limit for your type of house.
What to do next
First check with your council that no Article 4 direction or planning condition removes your permitted development rights. You do not need to apply, but you can get written proof with a lawful development certificate (£274 in England), which helps when you sell. Building regulations and the Party Wall etc. Act can still apply.
  • This is a guide based on the national rules for houses in England. Your council has the final say; flats, listed buildings and designated land have different rules. Wales, Scotland and Northern Ireland have their own rules.
  • Building regulations, the Party Wall etc. Act 1996 and (for listed buildings) listed building consent are separate from planning permission.

Add this to your project shopping list, then print it or take it to the merchant.

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How to use the planning permission checker

  1. Choose What are you planning? (an extension, loft work, porch, outbuilding, fence, driveway, solar panels, windows or a conservatory) and your Type of home.
  2. Type in the sizes it asks for: how far it sticks out, how high it is, and how close it is to the boundary. Each box has its own unit, so you can use metres, centimetres or feet.
  3. Say whether the property is on designated land (a conservation area, AONB, National Park, the Broads or a World Heritage Site) and whether the building is listed.
  4. Answer the Article 4 question if you can. If you don't know, leave it on "I don't know" and the result will remind you to ask your council.
  5. Read the verdict and the reasons under it. Tap Copy result to keep the answer, or Share link to send it to your builder or designer.

Why use this calculator

It gives one clear answer, not a maze of pages. You get one of four verdicts: likely permitted development, likely needs prior approval (not full planning permission), likely needs planning permission, or check with your council.

It shows the reasons. Every limit it checks is listed with your own numbers, so you can see which rule you are inside or outside. That helps if you want to redesign something to fit.

It treats awkward cases honestly. It counts earlier extensions in the total, it asks about conservation areas and listed buildings, and when it can't be sure it says so and tells you to ask your council.

It points you to the cost. If you need to apply, you see the fee. If you don't, you see what a lawful development certificate would cost.

How we worked it out

Your numbers, step by step. This updates as you change the calculator.

  1. OK: Sticks out 3 m, within the 3 m limit for your type of house.
  2. OK: Height 3.5 m is within the 4 m limit.
  3. OK: Eaves 2.4 m and 2.5 m from the boundary are within the eaves rule (3 m if within 2 m of a boundary).
  4. Note: Your council may have removed permitted development rights with an Article 4 direction or a condition on the original planning permission. Ask them; if they have, you need to apply.
  5. Note: The extension must not be higher than the highest part of the existing roof or have eaves higher than the existing eaves, and it cannot include a veranda, balcony or raised platform over 30 cm.
  6. Result: Likely permitted development (no application needed).

What the words mean

  • Permitted development is a set of national rules that let you build some things without applying. If your project stays inside every limit, you don’t need planning permission.
  • Prior approval is a lighter check. For a larger single-storey rear extension (up to 6 m, or 8 m on a detached house) you tell your council first. The fee is £249 in England. Your council tells your neighbours and then decides. You can start when it says no approval is needed, when it gives approval, or when 42 days pass with no decision.
  • A lawful development certificate is a legally binding answer from the council that your work is lawful. Anyone can apply. For planned work the fee is half the full application fee, which is £274 for a householder project in England. For work already done it is the same as the full fee.
  • An Article 4 direction is when a council removes some permitted development rights in an area. A condition on the house’s original planning permission can do the same. Neither shows up in the national rules, so ask your council.

How the check works

You choose a project. The calculator checks each limit for that project against the sizes you entered. Some examples of the limits it uses:

  • Rear extension: sticks out no more than 3 m past the original back wall (4 m if detached), no higher than 4 m, and eaves no higher than 3 m if within 2 m of a boundary. Earlier extensions count towards the total.
  • Two-storey extension at the back: no more than 3 m out, and at least 7 m from the back boundary.
  • Side extension: single storey, no higher than 4 m, and no wider than half the original house.
  • Loft: extra roof space of 40 m³ for a terraced house, 50 m³ for others. The new roof stays 200 mm back from the eaves, as far as practical.
  • Porch: no more than 3 m² on the ground, 3 m high, and at least 2 m from a boundary next to a road.
  • Outbuilding: single storey, eaves no higher than 2.5 m, and covering no more than half the land around the original house together with any extensions.
  • Fence, wall or gate: 1 m high next to a road, 2 m elsewhere.
  • Driveway: no more than 5 m² of front garden with a non-porous surface.

If any limit is broken, the verdict is “Likely needs planning permission”. If something can’t be decided from your answers, you get “Check with your council”. If the only issue is a rear extension between the normal and larger limit, you get “Likely needs prior approval (not full planning permission)”. If everything is inside the limits, you get “Likely permitted development”.

What we assume

  • The property is a house in England. Flats and maisonettes don’t have these householder rights, and nor do houses made from a change of use under the other permitted development classes.
  • The “original house” means the house as it stood on 1 July 1948, or as first built if that was later.
  • Designated land means a conservation area, AONB, National Park, the Broads or a World Heritage Site. The limits there are tighter. For example, larger home extension prior approval isn’t available, and a side extension needs permission.
  • The solar rules changed on 27 August 2026. Until 27 August 2027 you can follow either the old rules or the new ones. This tool uses the new ones. We read them from the Planning Portal pages, not from the legal Order itself.
  • We found no confirmed change to the householder extension limits at the time of checking.
  • Wales, Scotland and Northern Ireland have their own permitted development rules. They are not covered here.
  • This is a guide, not legal advice. Your council has the final say.

Tips

  • Ask your council before you build, especially if you aren't sure about a conservation area or an Article 4 direction. Councils have the final say, and the national rules are only the starting point.
  • Permitted development is not the same as no rules at all. Building regulations, the Party Wall etc. Act and listed building consent are separate. For a shared wall, see our party wall notice guide.
  • Measure from the original house. Earlier extensions count towards the limit, and so does any extension a previous owner built.
  • Planning to apply? Work out the total bill, including drawings and building control, with the planning permission cost estimator.
  • A lawful development certificate is worth having if you plan to sell. It is written proof, from the council, that the work was lawful.
  • Thinking about the price of the project itself? Try the house extension cost calculator or the conservatory cost calculator.

FAQs

Do I need planning permission for a conservatory?
Often not. A conservatory counts as an extension, so on a house in England it can stick out up to 3 m from the back of the original house (4 m if detached), up to 4 m high, without an application. It must also stay within the other limits, such as eaves no higher than 3 m within 2 m of a boundary. Building regulations are separate.
Do I need planning permission for an extension?
Not always. A single-storey rear extension can stick out 3 m (4 m for a detached house) as permitted development. Up to 6 m (8 m detached) you need prior approval for a larger home extension, which costs £249 in England, and your council has 42 days to decide. Anything bigger needs a planning application.
Do I need planning permission for a shed, outbuilding or garden room?
Usually not, if it is a single storey, for use that goes with the house, and behind the front of the house. It can be up to 4 m high with a dual-pitched or hipped roof, 3 m with any other roof, and 2.5 m high within 2 m of a boundary. Eaves can be no higher than 2.5 m. Somewhere to sleep or live needs permission.
Do I need planning permission for a loft conversion?
Roof lights and many rear dormers don't, as long as you add no more than 40 m³ (terraced houses) or 50 m³ (other houses). The new roof can't be higher than the existing ridge, can't go on a front slope facing a road, and can't include a balcony. On designated land, such as a conservation area, a dormer needs permission.
Do I need planning permission for a driveway?
Not if the surface is porous (such as gravel or permeable block paving) or the rain drains to a lawn or border in your garden. Paving more than 5 m² of front garden with a non-porous surface does need permission. A dropped kerb is a separate application to your council.
Do I need planning permission for solar panels?
On a house in England, panels on a pitched roof can stand out up to 200 mm from the roof slope and can't go above the highest part of the roof. The rules changed on 27 August 2026, and until 27 August 2027 you can follow either the old rules or the new ones. Listed buildings and their grounds are not covered.
Do I need planning permission for a fence or wall?
Not if it is no higher than 2 m, or 1 m next to a road. Gates and walls follow the same limits. Permitted development doesn't cover a fence, wall or gate on or next to a listed building.

Last reviewed: 6 November 2026 · How we calculate · Report an error