Planning permission and permitted development explained

By Chris Pollitt · Last checked 6 November 2026 · 2 min read

Whether you want to extend your own home or you're buying with a project in mind, planning rules decide what you can do. Understanding the basics before you buy can save a lot of money and disappointment.

Permitted development

Many changes to houses in England can be made without applying for planning permission, under what are called permitted development rights. Typical examples include:

• Single-storey rear extensions up to 3 metres deep on an attached house or 4 metres on a detached house. Larger extensions, up to 6 or 8 metres, are possible through a prior approval process where neighbours are consulted.
• Loft conversions adding up to 40 cubic metres to a terraced house or 50 cubic metres to a semi or detached house, as long as dormers don't face the road.
• Outbuildings such as garden rooms and sheds, within limits on height and how much of the garden they cover.
• Porches and some internal changes.

There are conditions on materials, height and position for each. If you want certainty, you can apply to the council for a Lawful Development Certificate, which confirms the work is permitted development.

When rights don't apply

Permitted development rights are reduced or removed in conservation areas, national parks, areas of outstanding natural beauty and for listed buildings. Flats and maisonettes don't have the same rights as houses. Councils can also remove rights in particular areas with an Article 4 direction, or for particular estates through planning conditions. Always check with the council first.

Applying for planning permission

For anything beyond permitted development, you apply to the local council. A householder application for an extension usually takes around eight weeks to decide. Neighbours are notified and can comment. Councils judge applications against their local plan, considering things like design, impact on neighbours' light and privacy, parking and character.

Many councils offer pre-application advice for a fee, which can tell you whether a scheme is likely to be approved before you spend money on full plans.

Building regulations

Building regulations are separate from planning and apply to almost all building work, including most permitted development. They cover structure, fire safety, insulation, drainage and ventilation. You'll need sign-off from council building control or an approved inspector. Missing sign-off can cause problems when you sell.

Buying with a project in mind

Before buying a home to extend, convert or redevelop, look at the planning history for the property and its neighbours on the council's planning portal. Similar approved extensions nearby are a good sign. Refusals nearby tell you what the council won't accept. For bigger projects, such as building a new home in a garden or converting a house to flats, get advice from a planning consultant or architect before you commit.