Double Storey Extension

Double or 2 Storey house extensions

Extensions of more than one storey are restricted to a depth of 3m for all houses.

2 storey rear extensions are a great way to enhance your home by increasing the size of the existing rooms at the rear of the property. You are not only adding space to the downstairs lounge, kitchen, dining room or other living areas, you are increasing the available space upstairs by adding a further bedroom, bathroom or study. If you are looking for a bigger home but moving house is not an option, then a 2 storey extension may be the answer for you as a more cost effective approach to gaining a larger home .

I need Planning Permission of a 2 storey rear extension?

You can construct a 2 storey rear extension without the need to apply for planning permission to your Local Planning Authority, provided that the following parameters are met;

  • Your property must not be located within a Conservation Area, a National Park, an Area of Outstanding Natural Beauty or The Broads
  • As a result of the extension, the total area of ground covered by buildings within the curtilage of the dwelling house (other than the original house), must not exceed 50% of the total area of the curtilage (excluding the ground area of the original house)
  • The height of the extension must not exceed the height of the highest part of the roof of the existing house
  • The height of the eaves of the extension must not to exceed the height of the eaves to the existing house
  • The extension must not to extend beyond a wall which fronts a highway, and forms either the principal elevation or a side elevation of the original house

The extension must not:

  • extend more than 3 metres from the rear wall of the original house
  • be within 7 metres of the rear boundary of the curtilage of your house
  • be within 2 metres of any boundary of the curtilage of your house
  • include a veranda, balcony or raised platform
  • include the installation, alteration or replacement of a micro antenna
  • include the installation, alteration or replacement of a chimney, flue or soil and vent pipe
  • include an alteration to the existing roof of the house


  • The external materials of the extension must be similar to the external materials used to construct your existing house
  • Any upper floor window located in the wall or roof slope forming a side elevation of your house must be fitted with obscure glazing and non opening windows, unless the opening is more than 1.7metres above the floor of the room in which the window is installed

The roof pitch of the extension must have the same roof pitch as the existing houseIn the event, one or more of the above is not complied with, it would result in your development being not permitted, and an application will be required to be submitted for planning permission

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