Do You Need Planning Permission in London? The Complete Guide

Three separate questions

Whether you can go ahead with a home project in London comes down to three separate questions, and it helps to keep them apart. First, does it need planning permission — or is it "permitted development" you can do without applying? Second, does it need building regulations approval for how it is built? And third, are there other consents — a listed building, a conservation area, a lease, a tree, a sewer? A project can engage all of these at once, and getting one does not settle the others. This guide walks through each, with a link to the detail for your project.

Two facts shape almost every answer in prime London. Permitted development rights are frequently reduced or removed here — by conservation-area status, an Article 4 direction or a listing — and they do not apply to flats in the way they do to houses. So the same project can be permitted development on one street and need a full application on the next.

Extensions, lofts and garden buildings

For a house, a single-storey rear extension can often be permitted development, and a deeper one may be possible through the prior-approval scheme. A loft conversion can be permitted development too — but not in a conservation area, where the roof rights are removed. A garden room or outbuilding is usually permitted development within height and coverage limits, as long as it is not lived in as a separate home. Each has its own limits, which the linked guides set out.

Conversions and changes of use

Changing how a property is used can need permission even without building work. Converting a house into flats always needs full planning permission. Letting rooms as a small HMO, working from home or short-letting each have their own lines — and in London an Article 4 direction or the 90-night short-let rule often decides the answer.

Heritage: conservation areas, listed buildings and trees

Prime London is heavily designated, and heritage controls catch things owners do not expect. Conservation-area status tightens what you can do; a listed building needs consent for almost any change; replacing windows can need permission under an Article 4 direction; demolishing a building in a conservation area usually needs permission; and works to protected trees need consent or notice. Unauthorised work to a listed building or a protected tree is a criminal offence, so these are worth confirming first.

Basements, services and energy

Below ground and around the services, other controls apply. A basement usually needs a Basement Impact Assessment, and building over or near a public sewer needs a build-over agreement from the water company. Adding solar panels or a heat pump is usually permitted development (the heat-pump rules were relaxed in 2025), and paving a front garden is fine with a permeable surface but needs permission over 5 square metres of impermeable paving.

Building regulations, costs and refusals

Separately from planning, most building work needs building regulations approval — the two are not the same. On cost, the council fee and our fixed fee are both knowable up front (you can work them out with the cost estimator), and larger projects may attract the Community Infrastructure Levy. And if an application is refused, you have options — a householder appeal or a revised resubmission.

How to be sure

The honest answer to "do I need planning permission?" always depends on the specific property — its designations, its planning history and the exact works. Where a project is permitted development, a lawful development certificate confirms in writing that it is lawful, which is worth having for your own certainty and for a future buyer. Where it is not, the right application is the route. If you would like this checked for your address, try the planning checker, or send us the property and the works and we will confirm the position.