How to add a rear extension under permitted development

Relaxed planning laws could help you to transform your ground-floor space without the cost or (sometimes) lengthy wait of a formal application

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If you’re planning a single-storey, ground-floor extension at the back of your house and you live in England, it is highly likely you will not need to make a planning application. 

The relaxation in planning rules allows a doubling of the length of single-storey rear extensions allowed without a planning application, giving homeowners greater opportunity to add more space to their home, perhaps in the form of an open-plan kitchen-diner extension or spacious living area.

What it means

Under current permitted development (PD) rules relating to single-storey extensions, you can plan and build a structure up to six metres from the original rear wall of the house (eight metres on a detached property) and up to four metres in height as long as it is completed by 30 May 2019.

What do you have to do?

While a formal planning application is not needed if the proposed single-storey extension is within the size restrictions outlined above, if you plan to take advantage of the extended PD rights – by adding an extension over three metres from the original rear wall for an attached house, or four metres for a detached – then ‘prior approval’ must be sought. This process, done through your local authority, is to allow neighbours to be consulted, requiring a written description, with key dimensions and a to-scale site plan, to be submitted.

If your adjoining neighbours do not object within the 21-day consultation period, the council will issue an approval notice. There is no application fee and the local authority has 42 days to respond from the date received. If neighbours do object, the council will consider the impact on the amenity of their property and decide whether it is reasonable. If the application is refused, there is an appeals process.

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What types of property have permitted development rights?

PD rights apply to dwelling houses, not flats, and may be restricted or removed by the local authority by planning conditions that were applied by a previous approval, or because the property is located within a designated Conservation Area, Area of Outstanding Natural Beauty, World Heritage Site or Sites of Special Scientific Interest (SSSI).

The finer details of lawfully building a rear extension

Bear in mind that the back of a property is taken as the original rear wall, or as the building stood on 1 July 1948, so this could affect the size of extension allowed, or if PD is applicable. If the original wall has changed, check what’s allowed with your local authority.

  • The extension must be built in accordance with the approved details, and use materials of a similar appearance to the rest of the house.
  • No part must be more than four metres in height and the eaves no more than three metres within two metres of any boundary.
  • All extensions and outbuildings must not cover more than 50 per cent of the original garden area. (See for full conditions.)

Prior approval does not automatically mean the development can proceed, as it does not negate any overriding interests such as restrictive covenants and easements, including rights of way and right to light, so always check title deeds, while listed buildings will also require listed building consent.

Need to know

To take advantage of relaxed PD rules relating to single-storey extensions, you must:

  • live in England;
  • not live within a Conservation Area, Area of Outstanding Natural Beauty, World Heritage Site or SSSI;
  • complete the build before 30 May 2019;
  • live in a dwelling house, not a flat;
  • seek prior approval.

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