Planning permission is normally required for any form of “development.” This includes building work, engineering operations, mining, or making a material change of use to a building or piece of land. The full legal definition is set out in Section 55 of the Town and Country Planning Act 1990.
However, several pieces of legislation allow certain works to take place without obtaining full planning permission
Permitted development rights
The Town and Country Planning (General Permitted Development) (England) Order 2015 (GPDO) effectively grants nationwide permission for many small‑scale or minor forms of development. This typically covers alterations and extensions to existing houses and bungalows (e.g. conservatories and dormer windows) and outbuildings and other structures within their grounds (e.g. garden sheds and garages). Flats do not have permitted development rights as they don't constitute a ‘dwellinghouse’ under the legislation.
Sometimes a local planning authority (LPA) can remove specific permitted development rights by making Article 4 Directions. Your LPA should be able to advise whether this applies to your area. Planning conditions attached to planning permission can also take away specific permitted development rights.
Changes of use
The Town and Country Planning (Use Classes) Order 1987 (as amended) groups land and buildings into different “use classes.” You will usually need planning permission to change from one use class to another, although there are exceptions where the legislation allows some changes between different uses.
Checking if you need planning permission
If you’re unsure whether your proposal needs planning permission, your LPA can advise you. They may suggest applying for a lawful development certificate to confirm that your proposed use or works are lawful and do not require planning permission.