The garden backs onto a builder's yard that's been quiet for years. The house next door has scaffolding up. The loft conversion in the house you're buying looks great, and nobody's mentioned whether it had permission.

Here's the plain version. Three separate questions hide under "check the planning". What's planned around the property, which changes your light, outlook and noise. What you'd be allowed to do to it, which changes what it's worth to you. And whether work already done to it was lawful, which can become your problem the day you complete. All three are answered from public records, and none of them appears on a listing.

This is about England. Planning law in Wales, Scotland and Northern Ireland is different.

What the planning register actually is

Every local planning authority has to keep a register of every planning application in its area. That's article 40 of the Development Management Procedure Order 2015. Part 1 holds applications still pending, with the plans and drawings. Part 2 holds the decided ones, including the decision, the conditions attached, any appeal and any planning obligations. Certificates of lawfulness go on it too.

It's searchable by address. The law allows a council to put the register on its website rather than requiring it, so the usual route is the council's online planning search. If you can't find it there, ask the planning department.

Neighbours aren't always told. For a standard application, the council either puts up a site notice "for not less than 21 days" or writes to the adjoining owners or occupiers. One or the other, not both. If you're buying, you're not the neighbour yet, so nobody writes to you. A laminated notice on a lamp post may be all the warning there is.

Decisions take a while. The statutory period is 8 weeks for most applications and 13 weeks for major development. Something submitted last month is very likely still undecided, so look at Part 1, not just Part 2.

What to look for around the property

Search the property's own address first, then work outwards: the houses either side, the ones behind, and the ones opposite.

Refused applications matter as much as approved ones. A refused extension next door is a sign someone wants to build there and may try again, or appeal. The decision notice says why it was refused, which tells you what the council cares about on that street.

Bigger sites tell you more. A builder's yard, a garage block or a pub car park behind the garden are exactly the sites that get redeveloped. If there's a live application, read the plans for height and windows facing your way. If there isn't, the council's local plan shows which sites are allocated for development. An allocated site won't appear as an application until someone applies, which can be years after you've moved in.

Some big extensions go through a lighter process. A larger single-storey rear extension can be built under permitted development after a "prior approval" application, where the council notifies adjoining owners and occupiers, gives them at least 21 days to comment, and has 42 days to decide. They appear on the register, often under a different label from a full application, so don't skip them.

For London listings, Nookaly shows a three-year count of planning applications approved and refused in the surrounding area, from the Planning London Datahub. It's a quick read on how much is changing nearby, not a substitute for searching the actual addresses.

What you'd be allowed to do

Most houses come with permitted development rights: a set of extensions and alterations you can do without applying for planning permission. The householder rights don't apply to flats: the national rules define a "dwellinghouse" so that it excludes "a building containing one or more flats". For a house, two things can take them away.

Conservation areas narrow them automatically. In a conservation area, the national rules don't allow cladding the outside "with stone, artificial stone, pebble dash, render, timber, plastic or tiles", side extensions, or rear extensions of more than one storey without a planning application.

Article 4 directions remove them selectively. GOV.UK describes an article 4 direction as one that lets the council "withdraw specified permitted development rights across a defined area". It's common in conservation areas, and often aimed at the parts of a house you can see from the street. It doesn't ban the work. It "only means that a particular development cannot be carried out under permitted development and therefore needs a planning application". GOV.UK's advice for finding out whether one applies is to ask the local planning authority, so do.

If the house is cheap because "there's room to extend", these are the two things to check before you believe it.

Work already done to the property

This is the one that can cost you money after you've bought.

Ordinary planning breaches become immune, eventually. Since 25 April 2024, the council in England has ten years to take enforcement action against building work done without permission, from the date it was substantially completed. Work finished before that date stays under the old four-year limit. So an extension finished without permission in 2018 is long past the limit, and one finished in 2025 isn't clear until 2035. Ask the seller for the permission, or for a certificate of lawfulness, and check the register to see whether either exists.

Listed buildings are different, and much more serious. Under section 7 of the Planning (Listed Buildings and Conservation Areas) Act 1990, any works for the alteration or extension of a listed building "in any manner which would affect its character" need listed building consent. That includes inside. Doing them without consent is a criminal offence under section 9, with up to two years' imprisonment or a fine on indictment.

And there's no clock. Section 38 lets the council serve a listed building enforcement notice requiring steps "for restoring the building to its former state", and the Act sets no time limit on when it can do that. Councils' own enforcement policies say so plainly: a notice can be issued years after the work. If a previous owner took out a listed fireplace or knocked through a wall without consent, the council can require the new owner to put it back. That's you.

What to do about it

In the order you'd do it.

Search the address on the council's planning register. Read every application on the property itself, decided and pending, including conditions on anything approved.
Search the neighbours. Either side, behind and opposite. Read refused applications and their reasons, not just the approvals.
Look for the big sites. Anything behind the garden or across the road that's a yard, a garage block or a car park. Check the register for a live application and the local plan for an allocation.
Walk past and look for site notices. They're the only notice some applications get.
Ask the council two questions. Is the property in a conservation area, and does an article 4 direction cover it? Get the answer in writing if you're relying on being able to extend.
Check whether it's listed. Historic England keeps the National Heritage List for England, and it's searchable online. If it's listed, ask the seller for listed building consent for every alteration you can see.
For every extension or conversion, ask for the paperwork. Planning permission or a certificate of lawfulness, with dates. Your solicitor will raise this too, but you'll want the answer before you've paid for a survey.

The honest summary

The planning register tells you what's planned around a property, what you could do to it, and whether what's already been done was allowed. Neighbours only get a site notice or a letter, not both, and you're not a neighbour yet, so nobody will tell you. Ordinary unauthorised work in England is safe from enforcement after ten years for work finished since April 2024. Listed building work never is.

Search the street before you fall for the house.

Worth reading next: buying a flat above a shop or takeaway, noise, from railways to pubs, and what you can check, and how to check flood risk properly.

This is general information, not legal or planning advice. Rules described apply in England and are as at October 2026. Ask the local planning authority, and your solicitor, about any specific property.