Do You Need Planning Permission for a House Extension?

When an extension needs planning permission

Many extensions need no planning application, because permitted development rights let you extend a house within set limits and conditions, the Planning Portal says. Go beyond those limits and an application for householder planning permission is likely to be required. The rights apply to houses only, not to flats and maisonettes, converted houses, houses created through permitted development rights, or other buildings.

The depth, width and land limits count from the original house, which is the house as first built, or as it stood on 1 July 1948 if built before then, the Planning Portal’s guidance note says. An extension added since, by you or a previous owner, uses up part of the allowance.

Permitted development limits for each type of extension

Each type of extension has its own limits under the Planning Portal’s rules, on top of the rules every extension has to meet.

Type of extension	How far it can extend	Height	Other conditions
Single-storey rear	4 metres beyond the original rear wall if detached, 3 metres if not; 8 and 6 metres with prior approval	No more than 4 metres	No prior approval on Article 2(3) land
Side	Up to half the width of the original house	No more than 4 metres	Single storey only
More than one storey	3 metres beyond the original rear wall	No higher than the existing roof	Not within 7 metres of any boundary opposite the rear wall; roof pitch matching the house as far as practicable; upper-floor side windows obscure-glazed and non-opening unless the opening part is over 1.7 metres above the floor

A semi-detached or terraced house counts as any other house. A side extension of more than one storey always needs householder planning permission, and on Article 2(3) land so does every side extension and every rear extension of more than one storey.

Article 2(3) land is a conservation area, an area of outstanding natural beauty, an area specified for the enhancement and protection of the natural beauty and amenity of the countryside, the Broads, a National Park or a World Heritage Site, the guidance note says.

Rules every extension has to meet

Extensions and other buildings can cover no more than half the land around the original house, and no extension can be higher than the existing roof or higher at the eaves than the existing eaves, the Planning Portal says. Within 2 metres of a boundary, the eaves can be no more than 3 metres high.

Nothing can go forward of the principal elevation, or of a side elevation fronting a highway, and the exterior materials have to look similar to the existing house. Verandas, balconies, raised platforms, microwave antennas, chimneys, flues, soil and vent pipes and alterations to the existing roof are all ruled out, and on Article 2(3) land the exterior cannot be clad.

Prior approval for a larger single-storey rear extension

Prior approval lets a single-storey rear extension go over 4 and up to 8 metres beyond the rear wall of the original house on a detached house, or over 3 and up to 6 metres on any other house, the Planning Portal says. It is not available on Article 2(3) land or in a Site of Special Scientific Interest, and every other permitted development condition still applies, the guidance note says.

What a prior approval application includes

Apply to the local planning authority before work starts, with a written description giving how far the extension goes beyond the rear wall and its height at the eaves and at the highest point, plus a site plan, the addresses of the adjoining properties and a contact address, the guidance note says.

Most applications carry a fee on top of the cost of building the extension, and work solely to improve a disabled person’s home is among the exemptions, the guidance note says.

Prior approval steps: 21 days for objections, 42 days to decide

The council has a 42-day determination period, the guidance note says, and the stages run in this order.

Stage	What happens
Application	Sent before work starts, with the description, site plan, adjoining addresses, contact address and any fee
Notice	The council serves notice on adjoining owners or occupiers, giving the end of the 42-day period and the time they have to object
Objections	Neighbours have at least 21 days to object
Assessment	If a neighbour objects, the council decides whether the impact on the amenity of all adjoining properties is acceptable
Decision	Written confirmation that prior approval is not required, where nobody objected, or that the effect is acceptable; or a refusal, which can be appealed
Building	Work can go ahead on that confirmation, or if no decision is notified within the 42 days

The process cannot be done retrospectively, and the extension has to be built as approved, or as submitted if no decision came within the 42 days, the guidance note says.

Article 4 Directions and listed buildings in Nottingham

An Article 4 direction can remove some or all permitted development rights, for example within a conservation area or the curtilage of a listed building, the Planning Portal says. In Nottingham, directions cover specific properties, mostly within conservation areas, in six areas: Devonshire Promenade, Foxhall Road, Sneinton, Strelley Village, Waterloo Promenade and Wellington Terrace.

They restrict minor building work such as small extensions, outbuildings and changes to windows and doors, so planning permission is needed instead, and Nottingham City Council advises using its Minor Works Enquiry Service before doing work in those areas.

Most building work to a listed building, internal and external, needs listed building consent, and the council’s My Property map shows whether a property is listed or in a conservation area, the council says.

Checks before you build without planning permission

Check the house and where it stands first, since a flat, a listed building or an Article 4 Direction changes the answer however small the extension.

Building regulations approval is a separate matter from planning, and the Planning Portal says most extensions need it.

Of the ten Nottingham building firms we compare, Traditional Build, a Federation of Master Builders member, offers architectural drawing and planning, and Edge Building & Construction builds extensions with a team of architects, interior designers, structural engineers and contractors that takes a project from conception to completion.