PLANNING RULES FOR SIDE EXTENSIONS

Photo of house with side extension and aluminium dormer window

SIDE EXTENSIONS AND PLANNING PERMISSION

If you want to add an extension to side of your house, you may need planning permission โ€“ requiring a planning application to your local authority.ย 

Planning applications cost money, take time, and require an assessment to be made by a local planning authority officer.ย  Your neighbours will be consulted and can object to your proposals.ย 

However, as with any extension to your house, you can undertake certain works without the need to apply for planning permission – subject to โ€˜permitted developmentโ€™ rules being met in terms of extension size, type and location.ย  ย ย 

The relevant rules are set out in the Town and Country Planning (General Permitted Development) (England) Order 2015, as amended.ย ย ย ย 

Rules for extensions to the side of your house are fairly strict, particularly where they are located close to boundaries which may affect the amenity of neighbours.ย 

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SIDE EXTENSIONS – PERMITTED DEVELOPMENT RULES

See: Part 1 of the GPDO

Side extensions to a house will be classed as permitted development, so long as:

It does not front/face on to a highway (which could include a footpath, not just a road)

The total area of ground covered by the extension as well as other buildings within the curtilage of the dwelling does not exceed 50% of the total area of the curtilage (excluding the ground area of the original house*)

The height of the extension does not exceed the highest part of the roof of the existing house

The height of the eaves of the extension does not exceed the height of the eaves of the existing house

Where the extension is to be within 2 metres of any boundary of the property, the height of the eaves of the extension does not exceed 3 metres

The extension is single storey – more than one storey requires a planning application

The extension does not exceed 4m in height

The extension does not have a width greater than half that of the original house

The materials used in any exterior work (other than those used for a conservatory) must be of a similar appearance to those used in the construction of the existing house

* the “original house” is as built or as it stood on 1 July 1948 (if it was built before that date)

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SEPARATE RULES APPLY TO:

  • Porches
  • Decking, balconies and raised platforms
  • TV aerials or satellite dishes
  • chimneys, flues or soil and vent pipes
  • Any alteration to the roof of the existing house
  • Changes of use

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PERMITTED DEVELOPMENT – PROTECTED AREAS – SIDE EXTENSIONS

If you live in any of the areas listed below, additional limitations on โ€˜permitted developmentโ€™ will apply:

  • Conservation Areas
  • Areas of Outstanding Natural Beauty
  • National Parks
  • the Broads
  • World Heritage Sites

In these areas, rear extensions are not permitted development and a planning application will be needed.ย 

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REMOVAL OF PERMITTED DEVELOPMENT RIGHTS

Permitted development rights can also be removed by your local planning authority, either through the addition of a Condition on a previous planning permission, or through imposition of an Article 4 Direction.ย 

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CONTACTING YOUR LOCAL PLANNING AUTHORITY BEFORE COMMENCING WORKS

For the purposes of planning, contact with the local planning authority is generally only necessary before carrying out permitted development where:

  • โ€˜prior approvalโ€™ from the local planning authority is required under PD rules
  • a โ€˜neighbour consultation schemeโ€™ is in place
  • the local planning authority has a Community Infrastructure Levy in place which requires developers to contact the local planning authority before carrying out permitted development. Failure to do this may result in the local planning authority imposing a surcharge on a developer
  • the permitted development rights require the developer to notify the local planning authority of a change of use

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Schedule 2 of the GPDO sets out when any advance notification is required.ย  If you are in any doubt, contact your local planning department or seek professional advice.

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PERMITTED DEVELOPMENT RIGHTS FOR FLATS, SHOPS AND BUSINESSES

Permitted development rights under Part 1 of the GPDO only apply to houses โ€“ they do not apply to flats, maisonettes or other buildings.ย 

Check out our guides to non-householder PD rights (through the menu at the top of this page).ย 

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PERMITTED DEVELOPMENT RIGHTS AND CIL

If a development is over 100 sq m in size, it may be liable for a charge under the Community Infrastructure Levy (CIL).

Check with your local planning authority whether they use CIL in your area and whether it applies to permitted development.ย 

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AND FINALLY …ย ย 

PD rights are subject to change.ย  The guide above is for general information only and does not constitute advice.ย  Local and site-specific circumstances can differ and affect whether a planning application is needed.

Other consents (such as Building Regulations or notifications under the Party Wall Act) may also be needed.ย 

To determine whether planning permission or other consents are required, seekย professional advice or clarification from your local authority before starting works.

TownPlanning.info has an extensive catalogue of articles and guides which help explain the town planning system in England. 

See below for links to some of our most popular pages or use the search function and menus at the top of the page.  

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