Do flats and maisonettes have permitted development rights?

No. Permitted development, the set of changes you can make without applying to the council, applies to houses only. It does not apply to a flat, or to a maisonette, which is a flat set over two floors. In prime central London most homes are flats, so for most addresses there is no permitted development, and the route is full planning permission. Even owners of a whole house often lose these rights to a conservation area, an Article 4 direction, or a listing.

Do I need planning permission to renovate in Kensington and Chelsea?

It depends on the work and the address. Internal changes to a building that is not listed often need no permission. External work, structural work, or any work to a flat usually does need it. A conservation area, a district protected for its historic character, removes rights you would have elsewhere, and an Article 4 direction can remove more. If the building is listed, you also need listed building consent, the separate permission to change a listed building, on top of any planning permission.

What is an Article 4 direction?

It is a rule a council makes to switch off specified permitted development rights in a defined area. Conservation areas commonly have one. Where an Article 4 direction applies, work that would be automatic somewhere else needs a full planning application instead. These directions can reach small jobs, such as a front door or a front window. You check whether one covers your home through the council's planning pages, or by asking the council in a pre-application enquiry.

Does permitted development apply in a conservation area?

It is restricted there. A conservation area is a district the council protects for its historic character. Some permitted development rights are removed by the national rules, and others by an Article 4 direction the council adds on top. So even the owner of a whole house in a conservation area loses much of the permitted development they would have elsewhere. Kensington, Chelsea, Mayfair, Belgravia and Marylebone sit largely within conservation areas, so this affects most projects here.

How can I be certain a job does not need planning permission?

Apply for a Lawful Development Certificate. A Lawful Development Certificate, or LDC, is a formal letter from the council confirming that a specific job is lawful and needs no planning permission. You apply for it before work starts, so you have certainty up front. It also gives a clean answer years later, when a future buyer's solicitor asks. It takes around eight weeks and does not expire. For an early steer, pre-application advice from the council is the lighter, quicker option.

Permitted Development vs Planning Permission London

Start with what you read online

You are planning one change to your home. Nothing dramatic. New windows at the back, perhaps, because the old ones are draughty. Or a small extension off the kitchen, to make room for a proper table. Before you spend any money on it, you want to settle one thing: whether you need permission from the council.

So you do the sensible thing. You search online and you find a national planning guide. You read the section that covers your kind of job. The guide tells you it counts as permitted development, which is the set of changes the law lets you make without applying to the council. No form. No fee. No waiting. You close the laptop and you start getting quotes.

Then someone who knows the area, a planning consultant or the council's own planning team, tells you the opposite. You need full planning permission. That is the permission you apply for and wait on, the one the council decides case by case, with a fee, and with no promise of a yes.

Nobody lied to you. The guide was accurate. It was simply written for a different house.

National guides describe the average English home. Picture it. A house on its own plot, with its own roof and its own front door, on an ordinary street, with nothing about it that the council protects. That house has real freedoms, and the guide lists them fairly. The problem is the distance between that house and yours. This part of central London is some of the most protected ground in the country, and the guide you read was written as if that protection did not exist.

What permitted development actually is

Start with the thing itself, plainly.

Permitted development, shortened to PD, is a list of changes the law has already said yes to. You do not apply for them. You do not pay the council a fee. If your job fits the list, you are allowed to build it, and that is the end of it.

The list is not invented by each council. It comes from one national law passed in 2015, the General Permitted Development Order. The part of it that deals with homes is Schedule 2, Part 1. That is where the law sets out what a house may do without asking permission, and it puts a size limit on each kind of work.

Those limits are exact. A single-storey extension at the back can reach out only so many metres. A loft conversion has a cap on its size, measured in cubic metres of new roof space. These are numbers, not guidelines. A centimetre over the limit and the right is gone, and you are back to applying like everyone else. The government's technical guidance lists the limits in detail.

Now the point that decides everything that follows, and the one most people read past. Permitted development is a fixed test. It is a yes or a no. Your job either fits the written rules or it does not. A planning officer reading the same rules should reach the same answer you reached at your kitchen table. There is no opinion in it, and nothing to argue.

Full planning permission works the other way around. It is not a list and it is not automatic. You fill in an application. You pay a fee. Then the council judges your plan on its merits: how it looks, how it sits next to the neighbours, what it does to the street and the wider area. Because it is a judgement, two similar plans on two similar streets can come back with two different answers.

One of these is a rule you can read for yourself. The other is a decision you have to wait for. The panel below sets the two side by side.

Permitted development

A fixed legal test

Yes or no, your job fits the rules or it does not

No application, no fee

You can read the answer yourself

Any officer should reach the same answer

Planning permission

A judgement on the merits

You apply, then wait

Carries a fee

Decided case by case

Two similar plans can get two different answers

A rule you can read, set against a decision you wait for.

The first question is not what you want to do. It is what you own.

Before any size limit matters, there is an earlier question, and most people reach it far too late. Permitted development for homes applies to one type of property, and one only: a house.

It does not apply to a flat. It does not apply to a maisonette, which is simply a flat arranged over two floors. It makes no difference whether the flat was purpose-built as flats or carved out of a grand old townhouse decades ago. If your home is a flat, householder permitted development does not apply to you at all. The Planning Portal says the same in plain terms: flats and maisonettes have no householder permitted development.

In central London this is not a rare exception. It is the normal case. In the Royal Borough of Kensington and Chelsea, shortened to RBKC, about four in five homes are flats. That is RBKC's own figure, taken from the 2021 Census. So for roughly four households in five, the whole permitted development list is beside the point before they have read a single limit.

Here is what that means once you are actually planning a job. Almost any change to the outside of your flat needs full planning permission. New windows at the front. A different front door. An air conditioning unit on the rear wall. A satellite dish facing the street. The kind of small jobs a house owner two streets away might finish in a weekend, you have to apply for and wait on.

There is also a second hurdle here, and it has nothing to do with the council at all. Most flats are leasehold. That means you own the inside of your home, but someone else, the freeholder, owns the building itself. A great many changes need the freeholder's written consent on top of the council's permission. The two are completely separate. Getting one does not get you the other, and a freeholder can refuse for reasons of their own that a planning officer would never consider.

So before you ask what you are allowed to build, ask the simpler question first. What do you actually own? For most people on these streets, that one answer settles the permitted development question on its own.

Even in a house, the area usually removes it

Suppose you are in the minority that does own a whole house. The permitted development list is open to you in principle. In most of central London, the location takes it away again.

Three things remove permitted development. In these boroughs, at least one of them applies to almost every address, and often more than one applies at once.

A conservation area. This is a district the council protects for its historic character, and most of Kensington, Chelsea and Westminster sits inside one. Inside a conservation area the rules tighten. To take one clear example, a loft or roof extension is never permitted development in a conservation area. It always needs an application.
An Article 4 direction. This is a council rule that switches permitted development off on a particular street or area. RBKC uses these heavily. One of them removes permitted development for basements across the whole borough. Others, in areas such as Ladbroke and Norland, reach all the way down to small things: the front windows, the front door, painting the front of the house, even the garden fence. RBKC publishes the list of its Article 4 directions. Where one applies, a job you assumed was automatic needs full permission instead.
A listing. If the building is listed, meaning it is officially recorded as having special historic interest, it needs its own separate permission on top of everything else. That permission is called listed building consent. Listing is a large subject with its own rules about what can change and what cannot, and it sits over and above the planning question entirely.

Put these together and the shape is clear. A flat removes permitted development by what it is. A conservation area, an Article 4 direction, or a listing removes it by where it is, or by what it is. In this part of London, most homes are caught by at least one of these, and many are caught by two or three at the same time.

How to find out what applies to your address

This is less daunting than it sounds. You can check most of it yourself, for nothing, before you spend a penny on drawings.

Begin with your exact address, not just your street. This matters more than people expect. Two houses on the same road can fall under different rules, because an Article 4 direction or a conservation area boundary can run down the middle of a street. So check the specific property.

The council publishes maps for both of the things that catch most homes. There is a map of its conservation areas, and a map of its Article 4 directions. Look your address up on each one. Between them, those two maps tell you most of what you need to know: whether your home is in a conservation area, and whether an Article 4 direction reaches it.

Where there is still a genuine question after that, there is a clean way to settle it for certain. A Lawful Development Certificate, shortened to LDC, is a formal letter from the council confirming that your particular job is allowed without planning permission. You apply for the "proposed" version before you build, while the work is still on paper. The Planning Portal explains how the certificate works. It takes around eight weeks to come back. Once you have it, it does not expire, so it stays in the file and answers the question for the next buyer's solicitor years later.

The fees are worth stating plainly, because one of them catches people out. From 1 April 2026, a householder planning application costs £548. A proposed Lawful Development Certificate costs £274, which is half the planning fee. Applying under permitted development costs nothing at all. Where an Article 4 direction has removed your permitted development, though, you still have to apply for planning permission, and you pay a fee for it. There used to be an exemption that made those applications free. It was removed in 2018, so the fee now applies like any other.

If you are working out the total cost of a project, the renovation cost calculator gives you an indicative range, and these application fees sit on top of that figure.

The question had the wrong shape

So the choice you thought you faced was never the real one. It was never permitted development or planning permission; it was always which of the things that remove permitted development applies to your address, and in central London at least one of them almost always does.

Which is why the answer has to come before the design, not after it. Find out what you own. Check the council's maps for your exact address. Get a certificate where the case is genuinely borderline. Do that work first, and you know what you are building, and what you must apply for, before a single line is drawn. Leave it until the design is finished, and you redraw the design. That is why Myrmex puts the permission question into the pre-construction stage, before the design is fixed.

Permitted Development or Planning Permission in Central London