Do I need planning permission? Check it in 3D
Many rear extensions, garden rooms and heat pumps need no planning permission in England or Ireland, if they stay inside national limits. Draw yours: the model shows those limits around your house and checks every condition against the official text.
Rules as of 10 October 2026. England: GPDO 2015 with the 2025 heat pump changes. Ireland: the exemptions in force since 27 July 2026.
Sample house
This browser cannot draw 3D (WebGL is off). Every condition below still works.
Fits permitted development as entered
Every condition this tool checks passes. This is not a formal decision.
This is a sample house, not yours: a semi-detached house with a 14 m garden. Change any size to make it yours, or start with your own house.
Every condition, with its source
Rules as of 10 October 2026
| Result | Condition | Your project | Limit | Source |
|---|
The report Pro writes
Take it to the council, or to your builder
Pro turns this check into documents. One payment covers every project you check.
- PDF report3D views, a dimensioned plan and elevations of the project, the verdict and the rules versionPro
- Rule-by-rule tableEvery condition with its citation, source and the date it was checkedPro
- Designated land checklistEach designation, what it changes and where to look it upPro
- Building regulations triggersKept apart from planning: what still needs approval or noticePro
- Next-step packEngland: lawful development certificate cover letter and document checklist, and the larger home extension prior approval checklist. Ireland: section 5 cover letter and checklist, and the Class 3A or 1A notice content with its compliance checklist.Pro
$29 once, every project
Buy Pro on GumroadGumroad handles payment and refunds. Your key turns Pro on in this browser. The documents prepare your application or notice; the council still decides.
How the check works
It reads your project the way the national rules are written: one condition at a time, each from the official text, each with its reference. A condition passes only when every figure it needs is entered and inside the limit. A missing answer, or a term that needs judgement, becomes a point to check, never a pass.
National rules are the starting point, not the whole picture. A listed building or protected structure, a conservation area, an Article 4 direction or a condition on an earlier permission can take them away. The tool asks about each one and links to the official maps. It does not look them up.
The result is not a formal decision. In England the council confirms it with a lawful development certificate; in Ireland with a section 5 declaration.
What changed in 2025 and 2026
| Date | Change |
|---|---|
| 27 July 2026 | Ireland: extensions up to 45 m² (from 40), garden buildings 30 m² (from 25), upper-floor windows 8 m from the boundary (from 11), new Class 3A detached house in the rear garden (32 to 45 m²) and Class 1A subdivision, both with 14 days’ notice and ending 31 December 2030; heat pumps no longer only at the rear. S.I. 338 to 344 of 2026 |
| 1 April 2026 | England: householder application £548, so a lawful development certificate for proposed householder works is £274; larger home extension prior approval £249. Fees Regulations 2012, regs. 11, 14, 18A |
| 29 May 2025 | England: air source heat pumps up to 1.5 m³ (from 0.6), two at a detached house, no 1 m boundary limit, heating and cooling allowed but not cooling only; MCS 020 a) is the sound standard. S.I. 2025/560 |
The rules, project by project
- IrelandThe new exemptions of 27 July 2026Every class that changed, with the old and new limits.
- IrelandExtensions: the 45 m² ruleAbove-ground limits, the 2 m and 8 m distances, open space.
- IrelandShed, garden room or log cabin: 30 m²Height, position and what it may be used for.
- IrelandA granny flat without planning: Class 3A32 to 45 m², 14 days’ notice, the end date.
- IrelandSection 5 declarations€80, 4 weeks, and what to send.
- EnglandHow far can I extend without planning?3 m, 4 m, 6 m and 8 m, two storeys, side extensions.
- EnglandGarden rooms: the 2.5 m ruleHeight within 2 m of a boundary, the 50% rule, uses.
- England and IrelandAir conditioning and heat pumpsThe 2025 English rules and Ireland’s Class 2(d).
- EnglandLawful development certificates£274 for householder works, 8 weeks, the documents.
Questions
Is the result a legal decision?
No. It compares what you enter with the national rules and shows the legal reference for each condition. Only the council can decide: in England with a lawful development certificate for proposed works (£274 for householder works from 1 April 2026), in Ireland with a declaration under section 5 (€80, answered within 4 weeks).
Does it check whether my house is listed or in a conservation area?
No. It asks you, links to the official maps, and turns any unanswered question into a point to check. Listed buildings, protected structures, conservation areas, architectural conservation areas, Article 4 directions and conditions on earlier permissions can all remove or limit the national rules.
Is anything I enter sent to a server?
No. The check and the 3D model run in your browser. The share link holds the project in the part of the address after the # sign, which browsers do not send to servers. If you buy Pro, only the licence key is sent to Gumroad to check it.
Why does it say a point needs a check?
Because an answer is missing or a term needs judgement, such as which wall is the principal elevation, whether the house is the original house, or where the curtilage ends. The tool never turns an unknown into a pass.
What about Wales, Scotland and Northern Ireland?
Their rules differ from England’s and are coming next. Until they are read and tested, the tool does not guess them.
What does Pro include?
For $29, once, for every project you check: a PDF report with 3D views, a dimensioned plan and elevations, every condition with its citation and check date, the designated land checklist, the building regulations triggers, and the next-step pack for your route.
Sources: GPDO 2015, Schedule 2, Part 1 and Part 14; S.I. 2025/560; MHCLG technical guidance; S.I. No. 338 of 2026 and S.I. Nos. 339 to 344 of 2026; Circular PLR 02/2026. Last checked 10 October 2026. legislation.gov.uk and GOV.UK content is used under the Open Government Licence v3.0; Irish Statute Book content under the Oireachtas (Open Data) PSI Licence, which incorporates CC BY 4.0. Not legal advice, and not affiliated with any council or government department.