Permitted development, telecommunications & prior notifications

What are permitted development rights?

Permitted development rights are a general planning permission granted by Parliament. They allow certain building works, such as adding a house extension and changes of use, to be carried out without the need for planning permission.

Some of these permitted development rights are subject to a prior approval process with the local planning authority, and have certain conditions and limitations applied, such as:

  • Larger single-storey rear extensions to residential properties (subject to a consultation process – see below)
  • Conversions between office and residential uses (subject to some restrictions – see below)

Check the Planning Portal for more information of permitted development rights for common projects. The GOV.UK website provides homeowners with permitted development rights technical guidance

Large household extensions

Householders can build larger single storey rear extensions under Permitted Development, subject to the neighbour consultation scheme

You can apply under this scheme for single-storey rear extensions of between 4m and 8m in depth for a detached house, or between 3m and 6m in depth for any other house, with a maximum height of 4m. This measurement is taken from the original rear wall of your house.

The extended permitted development does not apply to flats, maisonettes or houses that are listed buildings or located within a conservation area.

This is a prior approval system and cannot be done retrospectively. If work has started then this procedure cannot be used and a full planning application will be required.

Change of use from offices to residential

Office buildings (Use class B1a) and associated land can now be changed to residential buildings (Use Class C3) without the need for planning permission.

Development is not permitted where the building is listed, a scheduled monument or is located within a safety hazard area or in a military explosives storage area.

The building must have been used as an office prior to 29 May 2013. If it wasn’t a date must be supplied of when it was last used.

Prior to making any changes of use, developers must apply to us to determine whether the prior approval of the council will be required as to:

  • The transport and highway impacts of the development
  • Any contamination risks
  • Any flooding risks
  • Impacts of noise from commercial premises

If prior approval is required, development will be carried out in accordance with detail approved by the local planning authority.

Other aspects of development which may be associated with a change of use will continue to require planning permission, such as alterations to facades and extensions.


View application fees.

Applications that are invalid and where the additional information requested is not submitted in time will be returned with a 25% administration cost taken from the planning fee refund.

Telecommunications apparatus

A guide to telecom masts & the ‘Prior Approval’ application process

Certain forms of telecommunication development, for example, mobile telephone masts, are known as permitted development (under Schedule 2, Part 16 of the Town and Country Planning (General Permitted Development) Order 2015 (as amended)).

Under paragraph A.3.(3) of Part 16, if the mast is 25m in height or less the applicant is required to apply to the Council’s Planning Department for a determination as to whether or not the ‘prior approval’ of the authority will be required for the siting and appearance of the development.

This requires an assessment of the new masts impact on the local surroundings only, and the Planning Department will also look to see whether or not there are more favourable locations and whether there is already too much ‘street clutter’ in the vicinity of the site. These are the only matters that can be considered by the Planning Department when assessing a prior approval application, and the following saved Policy from the City of Southampton Local Plan is also relevant:

TI 5 Telecommunications

Proposals for telecommunications equipment and public utility infrastructure will be permitted, subject to the following provisions:

(i) that the design of the installation, including its height, materials, colour and use of screening respects the character and appearance of the locality;

(ii) that wherever practicable existing masts and sites or suitable buildings or other structures are utilised;

(iii) that technical requirements or constraints are demonstrated to outweigh any adverse environmental impact.

The Council has 56 days in which to let the mast operators know of its decision on whether prior approval is required for siting and appearance and to let the operator know of our decision to allow or refuse approval. If this target date is missed the mast is given express consent and can be erected regardless of the Council’s final decision.

The following items are needed for all prior approval applications:

  • Application form
  • Fee
  • Location plan (scale 1:2500 or 1:1250) with site outlined in red
  • Block plan (scale 1:500) or Site Plan (scale 1:200) – if the proposal will alter an existing building footprint or create a new building footprint
  • Site levels (scale 1:200) – if the proposal will lead to a change in the level of the land
  • Floor plans – proposed (scale 1:50 or 1:100) – if the proposal will create, alter or add to a floor
  • Elevation drawings – proposed (scale 1:50 or 1:100) – if the proposal will create, alter or add to a building
  • Evidence that the:
    • Southampton Airport has been notified of the proposal where it consists of the installation of a mast within three kilometres of the perimeter of the airport
    • Owner or agricultural tenant of the land to which the application relates has been notified of the proposed development
    • The relevant body of the school or college have been consulted about the proposal where it consists of the installation, alteration or replacement of a mobile base station on or near a school or college
  • A supporting statement covering:
    • Description of the proposed development, evidence that the possible use of an existing mast building or structure has been considered before submitting an application to erect a new mast
    • The purpose and the need for the particular development
    • Compliance with ICNIRP requirements
    • Height of the proposed antenna, the frequency and modulation characteristics
    • The details of power output

In line with the Council’s Constitution, the Local Planning Authority will erect a site notice in an appropriate location near to the proposed development giving the public 21 days to provide written comments. In addition the Council will write directly to any neighbouring properties with a common boundary to the application site, and this may be extended to include others within a reasonable proximity to the application site.

Further information about this type of application (electronic communications networks) is available on the Planning Portal.

Returning your application

  • Contact online
  • Post: Planning and Sustainability
    Southampton City Council
    Civic Centre
    Civic Centre Road
    SO14 7LY