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Do I Need Planning Permission?

The Article explains permitted development rights

Rules, known as ‘permitted developments’ rights, allow you to extend a house without needing to apply for planning permission if permission if specific limitations and conditions are met.

If you want to exceed these, then it is likely that an application for householder planning permission will be required.

If the work adds over 100 square metres of floor space, it may also be liable for a charge under the community infrastructure levy.

Please Note:

These rules apply in the context of the proposed extension and any previous extensions (i.e. the total enlargement’).

These rules apply to house only and not to:

- Flats and maisonettes

- Converted houses

- Other Buildings

- Areas where there may be a planning condition

For all extensions

- Only half the area of land around the “original house” can be covered by extensions or other buildings.

- Extensions cannot be higher than the highest part of the existing roof; or higher at the eaves than the existing eaves.

- Where the extension comes within two metres of the boundary* the height at the eaves cannot exceed three metres.

- Extensions cannot be built forward of the ‘principal elevation’ or, where it fronts a highway, the ‘side elevation’.

The work cannot include:

- Verandas, balconies or raised platforms

- A microwave antenna (e.g. TV aerial or satellite dish)

- A chimney. Flue or soil and vent pipe

- Any alteration to the roof of the existing house

The materials used in any exterior work must be of a similar appearance to those on the exterior of the existing house.

For side Extensions

Where it would extend beyond the ‘side elevation’ of the original house*, the extension:

- Cannot exceed four metres in height

- Can only be a single storey

- Can only be up-to-half the width of the original house*

For single storey extensions

- Single-storey rear extensions cannot extend beyond the rear wall of the original house* by more than four metres if a detached house; or more than three metres for any other house.

The limit for single-storey rear extensions is increased to eight metres if a detached house; or six metres for any other house.

- This requires that the relevant local planning authority is informed of the proposed work via a prior approval application.

- Single-storey rear extensions cannot exceed four metres in height

For Extensions of more than one storey

- Extensions of more than one storey must not extend beyond the rear wall of the original house* by more than three metres or be within seven metres of any boundary* opposite the rear wall of the house.

- Roof pitch must match existing house as far as practicable (note that this also applies to any upper storey built on an existing extension).

- Any upper-floor window located in a ‘side elevation’ must be obscure glazed; and non-opening (unless the openable part is more than 1.7 metres above the floor).

All side extensions of more than one storey will require householder planning permission.


Detailed advice on complying with these rules, illustrative examples, and further explanations of the terminology used in provided by government in the ‘Permitted development rights for householders: technical guidance’.

You are strongly advised to read this guidance to help understand how permitted development rules apply to the specific circumstances of any proposal.

Original House

Also known as the ‘original dwelling house’.

This means the house as it was first built; or as it stood on 1st July 1948 (if it was built before that date). Although you may not have built an extension on the house, a previous owner may have done so.


Also known as the ‘Boundary of the curtilage’

This means the edge of the area of enclosed space surrounding the house.

For example, a wall or fence between houses or gardens, or the wall of an adjoining building.

Please note that this is note a legal definition and a determination as to what constitutes the boundary may be made by the Local Planning Authority.

Designated Land

This is defined as land within:

- A conservation area; or

- An area of outstanding natural beauty; or

- An area specified by the secretary of state for the purposes of enhancement and protection of the natural beauty and amenity of the countryside; or

- The broads; or

- A National Park; or

- A World Heritage Site.

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