How we check our rules
Every limit on this site comes from a quoted clause of the law, with its location and the date we checked it. Nothing is rounded, converted or inferred. Where the law uses a judgement word, we explain it and ask you, instead of measuring it.
How rules are captured and quoted
We've captured 172 rules from the law. Each one carries the exact words of the clause, where it is (part, class and paragraph) and the date we checked it. A computer test re-finds every quote, word for word, in our saved copy of the official text, and the site won't publish if any quote is missing, paraphrased, or doesn't contain its own limit.
No limit is typed into a page by hand: every figure a checker shows is read from those rules, and a second test checks every figure in its results against the rules and your own entries, across hundreds of test designs.
The law we quote, from legislation.gov.uk (Open Government Licence):
- The Town and Country Planning (General Permitted Development) (England) Order 2015 (SI 2015/596), article 2. Text in force from 27 August 2026, checked 14 October 2026.
- GPDO 2015 (SI 2015/596), article 3. Text in force from 27 August 2026, checked 14 October 2026.
- GPDO 2015 (SI 2015/596), article 4. Text in force from 27 August 2026, checked 14 October 2026.
- GPDO 2015 (SI 2015/596), Schedule 1, Part 1 (article 2(3) land). Text in force from 27 August 2026, checked 14 October 2026.
- GPDO 2015 (SI 2015/596), Schedule 2, Part 1 (development within the curtilage of a dwellinghouse). Text in force from 27 August 2026, checked 14 October 2026.
- GPDO 2015 (SI 2015/596), Schedule 2, Part 2 (minor operations). Text in force from 27 August 2026, checked 14 October 2026.
- GPDO 2015 (SI 2015/596), Schedule 2, Part 14 (renewable energy). Text in force from 27 August 2026, checked 14 October 2026.
- Energy Act 2004 (c. 20), section 82 (definition of microgeneration, used by GPDO Part 14). Text in force from 18 September 2025, checked 14 October 2026.
- Planning (Listed Buildings and Conservation Areas) Act 1990 (c. 9), section 1 (listing; meaning of listed building, used by GPDO article 2(1)). Text in force from 10 August 2026, checked 14 October 2026.
- Town and Country Planning Act 1990 (c. 8), section 336 (interpretation; "highway"). Text in force from 14 September 2026, checked 14 October 2026.
- GPDO 2015 (SI 2015/596), Schedule 2, Part 11 (heritage and demolition). Text in force from 27 August 2026, checked 14 October 2026.
- Town and Country Planning Act 1990 (c. 8), section 196D (relevant demolition in a conservation area). Text in force from 14 September 2026, checked 14 October 2026.
- The Building Regulations 2010 (SI 2010/2214), regulation 9 (exempt buildings and work). Text in force from 1 October 2026, checked 14 October 2026.
- The Building Regulations 2010 (SI 2010/2214), Schedule 2 (exempt buildings and work). Text in force from 1 October 2026, checked 14 October 2026.
Official guidance we quote to explain words (never for a limit): Permitted development rights for householders: technical guidance (MHCLG, September 2019). It dates from September 2019 and covers Part 1 only, so it says nothing about fences, walls or gates.
Review passes
Whoever collects a rule doesn't check it. A separate reviewer reads each new or changed rule against the Order's text and its amending instruments, and every finding is fixed before a checker uses the rule.
- October 2026, Parts 1 and 2 (householder rights, fences): 119 first-draft rules reviewed: 82 correct, 1 wrong, 36 imprecise, 21 provisions missing. All fixed.
- October 2026, Part 14 heat pumps: 22 rules reviewed: 10 correct, 1 wrong, 11 imprecise. All fixed.
- Before a checker goes live: a fresh legal-accuracy reviewer, with no access to how it was built, checks every result against the Order's text across at least 20 test designs, including the boundary cases.
- Fence checker, 14 October 2026: 61 designs and 8 postcode runs on the checker, and 11 postcodes on the address page. 5 wrong results, 9 imprecise and 10 minor findings, all fixed or answered before launch (for example, a replacement fence now never keeps an old fence's extra height, and postcodes outside England no longer get a result).
Who has published what
Councils publish their own restriction data on planning.data.gov.uk, and many haven't yet. Out of 311 planning authorities in England, this is how many have published each dataset from their own records (counted 14 October 2026). Where a council hasn't, the address check says "not published by [council] centrally: check with them", never "none".
| Dataset | Councils publishing | Share |
|---|---|---|
| Conservation areas | 147 of 311 | 47% |
| Article 4 direction areas | 117 of 311 | 38% |
| Listed building outlines | 101 of 311 | 32% |
| Tree preservation order areas | 84 of 311 | 27% |
| Protected trees (points) | 79 of 311 | 25% |
National datasets cover all of England from one publisher: listed buildings and World Heritage Sites (Historic England); National Parks, National Landscapes and Sites of Special Scientific Interest (Natural England). Listed buildings are mostly mapped as points, so we say "a listed building is close to this postcode", never "your house is listed".
Judgement words
32 words in the law can't be measured from a drawing or a map, such as "adjacent to a highway", "principal elevation" and "incidental". For each we quote the official wording and guidance, and where we have them, how planning inspectors have read it in published appeal decisions (29 decisions so far, each read in full and quoted). Those readings are labelled as readings, not the law. A result that depends on one is amber: Check.
- curtilage
- principal elevation
- similar appearance
- adjacent to a highway used by vehicular traffic (11 inspectors' decisions)
- ground level (11 inspectors' decisions)
- highway
- fronts a highway
- extend beyond a wall
- rear wall
- verandah
- principal part (Class AA)
- dual-pitched roof
- purpose incidental to the enjoyment of the dwellinghouse
- classified road
- trunk road
- detached (Part 1 outside Class AA)
- obscure-glazed
- so far as practicable
- conservatory
- rear or side extension / hip-to-gable (Class B)
- faces onto, and is visible from (a highway or waterway)
- visible support structures (Class AA)
- detached dwellinghouse (Part 14)
- highway (Part 14)
- amenity of the area
- ground floor storey
- pitched roof / flat roof
- listed building
- relevant demolition
- trellis on top of a fence or wall (3 inspectors' decisions)
- former height (maintained, improved or altered) (4 inspectors' decisions)
- an obstruction to the view ... likely to cause danger
Keeping it current
- The law, monthly: we re-fetch the Order from legislation.gov.uk, compare it with our saved copy and every quote, and check for amendments not yet written into the text. 2 amending instruments currently have changes pending on legislation.gov.uk for the parts we use (SI 2026/1056, SI 2025/1315).
- Council data: the address files are rebuilt from planning.data.gov.uk, and the date of the current build is shown on the address page. Postcodes are refreshed from OS Code-Point Open each quarter.
Watch items
- SI 2026/1056 (EV wall chargers) (21 October 2026): Comes into force on 21 October 2026. It changes Part 2 Classes D and E (electric vehicle charging points) and other Parts, not the fence, outbuilding, extension, loft or heat pump rules. Checked 14 October 2026. Source
- Warm Homes Plan: heat pump consultation (14 October 2026): The government's Warm Homes Plan says MHCLG and DESNZ "will consult on further permitted development rights for air source heat pumps" in 2026. No consultation had been published when we checked on 14 October 2026. Until a new Order is made, the current rules apply. Source
Data sources and credits
Contains public sector information licensed under the Open Government Licence v3.0. Open Government Licence
- planning.data.gov.uk: Source: planning.data.gov.uk (Ministry of Housing, Communities and Local Government), licensed under the Open Government Licence v3.0. © Crown copyright and database right 2026.
- Historic England: © Historic England 2026. Contains Ordnance Survey data © Crown copyright and database right 2026. The Historic England GIS Data contained in this material was obtained on 14 October 2026. The most publicly available up to date Historic England GIS Data can be obtained from HistoricEngland.org.uk.
- Natural England: © Natural England copyright. Contains Ordnance Survey data © Crown copyright and database right 2026.
- Office for National Statistics (council and National Park boundaries): Source: Office for National Statistics licensed under the Open Government Licence v.3.0. Contains OS data © Crown copyright and database right 2026.
- OS Code-Point Open (postcodes): Contains Ordnance Survey data © Crown copyright and database right 2026. Contains Royal Mail data © Royal Mail copyright and database right 2026. Contains National Statistics data © Crown copyright and database right 2026.
- Map: © OpenStreetMap contributors (ODbL), map tiles by Protomaps.
Software: MapLibre GL JS (BSD-3-Clause); PMTiles (BSD-3-Clause); Protomaps basemaps (BSD-3-Clause); Barlow Semi Condensed, Atkinson Hyperlegible and IBM Plex Mono fonts (SIL Open Font License 1.1).