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SINGLE STOREY EXTENSIONS - PERMITTED DEVELOPMENTS - DOUBLE STOREY EXTENSIONS - LOFT CONVERSIONS

Planning Guide For a Single-storey extension 

An extension or addition to your house is considered to be permitted development, not requiring an application for planning permission, provided certain limits and

conditions are met.

  • On designated land* - no cladding of the exterior.*Designated land (Article 2(3)) includes national parks and the Broads, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites.
  • On designated land* - no side extensions. Rear extension - No permitted development for rear extensions of more than one storey. The regime for larger single-storey rear extensions (see point 9) does NOT apply to houses on designated land.
  • No more than half the area of land around the “original house”* would be covered by additions or other buildings. Sheds and other outbuildings must be included when calculating the 50 per cent limit. The term ‘original house’ means the house as it was first built or as it stood on 1 July 1948 (if it was built before that date). Although you may not have built an extension to the house, a previous owner may have done so.
  • No extension forward of the principal elevation or side elevation fronting a highway.
  • Materials to be similar in appearance to the existing house.
  • Side extensions to be a single storey. Width of the side extension must not have a width greater than half the width of the original house. Side extensions to have a maximum height of four metres and width no more than half that of the original house.
  • If the extension is within 2m of a boundary, the maximum eaves height should be no higher than 3m to be permitted development.
  • Single-storey rear extensions must not extend beyond the rear wall of the original house* by more than 4m if a detached house; or more than 3m for any other house. Where not on designated land (Article 2(3)) or a Site of Special Scientific Interest, this limit is increased to 8m if a detached house; or 6m for any other house.
  • Maximum height of a single-storey rear extension of 4m.
  • Maximum eaves and height of extension no higher than the existing house.

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Planning Guide For a Two-storey rear extension (Extensions of more than one storey)

An extension or addition to your house is considered to be permitted development, not requiring an application for planning permission, provided certain limits and conditions are met.

  • On designated land extensions of more than one storey are not permitted development. * Designated land includes national parks and the Broads, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites.
  • Extensions (including previous extensions) and other buildings must not exceed 50% of the total area of land around the original house. The term ‘original house’ means the house as it was first built or as it stood on 1 July 1948 (if it was built before that date). Although you may not have built an extension to the house, a previous owner may have done so. * Sheds and other outbuildings must be included when calculating the above 50% limit.
  • Maximum eaves and ridge height of extension no higher than existing house. If extension is within two metres of a boundary maximum eaves height should be no higher than three metres to be permitted development.
  • Extensions of more than one storey must not extend beyond the rear wall of original house by more than three metres or be within seven metres of any boundary opposite the rear wall of the house.
  • Roof pitch of extensions higher than one storey to match that of the existing house, as far as is practicable.
  • Materials used in exterior work to be similar in appearance to those of the exterior of the existing house.
  • 7. Any upper-floor window in a wall or roof slope in a side elevation must be obscure-glazed and nonopening unless the parts which can be opened are more than 1.7 metres above the floor of the room in which it is installed.
  • 8. No balconies or verandas are permitted development.

Important note

  • The permitted development allowances described here apply to houses, not flats, maisonettes or other buildings. You should check with your Local Planning Authority whether permitted development rights apply – they may have been removed by what are known as Article 4 directions.
  • Other consents may be required if your house is listed or in a designated area.
  • As well as other important information you will find guidance here on the permitted development regime.

Building Regulations

  • Most extensions of properties require approval under the Building Regulations. For more information read Planning Portal online guidance.
  • Installation, alteration or replacement of a chimney, flue or soil and vent pipe


Definitions of terms used in this guide: ‘Original house’ - The term ‘original house’ means the house as it was first built or as it stood on 1 July 1948 (if it was built before that date). Although you may not have built an extension to the house, a previous owner may have done so


‘Designated land’ - Designated land (Article 2(3)) includes national parks and the Broads, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites.

SINGLE STOREY EXTENSIONS - PERMITTED DEVELOPMENTS - DOUBLE STOREY EXTENSIONS - LOFT CONVERSIONS

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Phone: 07591072160 | Email: [email protected] 

Planning and Building Regulation Drawing Package Prices

Compare our service packages and find the best fit for your house to home project.

A full written quote/contract will be drafted to be signed by you and 365 prior to any work with no hidden charges. Excluding VAT.

*Please note prices are only examples we can beat any like for like quote. 

Single Storey Extension

£649*

Based on a Mono Pitch Rear Extension 

Building Cost of £30K

Planning and Building Regulation Package

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Loft Conversion

£849*

Based on a Dormer Loft Conversion 

Building Cost of £30K

Planning and Building Regulation Package

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Double Storey Extension

£949*

Based on a Double Storey Extension 

Building Cost of £70K

Planning and Building Regulation Package

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