How to add a rear single storey extension without planning permission

Want to transform your home with a single storey extension but without planning permission? You may be able to do so under permitted development. Find out how

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Want to add an extension to your home without planning permission? Doing so will mean less (slightly) less paperwork and a (slight) cost saving, and it is entirely possible to do under the current rules.

So, if you’re considering building a single-storey extension at the back of your house, you live in England, and you plan your extension carefully, you may well be able to avoid having to make planning application, building under permitted development instead. 

Follow our expert guide to find out how to achieve your extension project without planning permission.

A flat roof extension and two storey extension

(Image: © Clear Architects)

What is an extension under permitted development?

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 an attached house (or eight metres on a detached property) and up to four metres in height, as long as it is completed by 30 May 2019.

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.

Can you extend your house under 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).

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.

How to build an extension without planning permission

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 from the local planning authority, and a neighbour consultation scheme implemented. 

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.

Bear in mind that:

  • 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 planningportal.co.uk 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.

What to do if your neighbours object to your extension

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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