Permitted development

Permitted development is a national grant of planning permission. If your project fits inside the limits, you do not need to apply — you can simply build.

The catch is that the limits are precise, the exceptions are numerous, and the penalty for getting it wrong is an enforcement notice and a demolition bill. This page is the honest version.

The first question: is it even available to you?

Permitted development rights do not apply at all if any of these are true:

• The property is a flat or maisonette. Flats have no permitted development rights for extensions or lofts. Full stop.
• The building is listed. Listed building consent is required for alterations regardless.
• An Article 4 direction applies. Councils use these to remove specific rights across a street, a ward or a whole conservation area. They are extremely common in London and in historic town centres.
• A planning condition removed the rights. Very common on newer estates and on houses created by a previous conversion.
• It is a new build under a covenant — not planning law, but it can still stop you.

Conservation area status does not remove all rights, but it restricts several — side extensions, cladding, and roof alterations among them.

Single-storey rear extensions

Other conditions apply throughout: no more than half the land around the original house may be covered by buildings; materials must be similar in appearance; no verandas, balconies or raised platforms above 300mm; and nothing forward of the principal elevation facing a highway.

Loft conversions

• Additional roof volume up to 40 cubic metres for a terraced house, 50 cubic metres for a detached or semi-detached house — cumulative, including any previous roof enlargement
• Nothing beyond the plane of the existing roof slope on the principal elevation facing a highway
• No part higher than the highest part of the existing roof
• Materials similar in appearance
• Side-facing windows obscure-glazed and non-opening below 1.7m above floor level
• Roof extensions other than hip-to-gable set back at least 20cm from the original eaves

Outbuildings, garden rooms and garages

• Single storey, incidental to the enjoyment of the house
• Maximum eaves height 2.5m; maximum overall height 4m for a dual-pitched roof, 3m otherwise
• Maximum height 2.5m in total if within 2m of a boundary
• Not forward of the principal elevation
• No more than half the land around the original house covered
• Not to be used as a separate dwelling — a garden room with a bed, a kitchen and its own front door is a house, and needs permission

Prior approval: the middle ground

Some larger works sit outside ordinary permitted development but still avoid a full application. Instead you apply for prior approval on specific matters only. The main routes we use:

With the larger home extension route the council notifies your adjoining neighbours. If none object within 21 days, approval follows. If one does, the council assesses the impact on amenity — and only that. Design is not up for debate.

Prove it: the Lawful Development Certificate

You are not required to get one. You should get one anyway.

A Lawful Development Certificate is a formal decision from the council confirming your work is lawful. It costs half a householder application fee and takes around eight weeks. Without it you are relying on your own reading of the legislation, and:

• Buyers' solicitors ask for it, and its absence delays or kills sales
• Lenders and insurers increasingly ask for it
• It is the only thing that definitively stops an enforcement argument later

It can be applied for before the work (a proposed certificate) or afterwards (an existing certificate). Before is far better.

Permitted development is not permission to ignore everything else

Even where no planning application is needed, you will still normally need building regulations approval, and you may still need a party wall award, and the work must still comply with fire, structural and thermal standards. These are separate systems with separate consequences.