Extensions covering more than one floor level

Most house extensions of two or more storeys will require planning permission. You will not need planning permission, however, if:

  • no part of the extension is in front of the principal elevation (front) of your house, or the side elevation where that elevation faces a road
  • no part of the extension is within 10 metres of the boundary of your property (the garden boundary)
  • the height of the extension is no higher than any part of the original house (excluding the chimney)
  • the area of ground covered by the extension is no more than that covered by the original house; and
  • the area of ground covered by development (including the proposed extension, any previous extensions and any other buildings, but not the original house) in either the front or back garden is no more than half the area of that part of the garden.

You will need planning permission if your house is located in a conservation area, and you will need listed building consent if your house is listed.

Two storey extensions can be problematic; if not positioned away from any mutual boundaries they can give rise to overshadowing or loss of light for your neighbours. If you're planning a two storey extension we would advise you to show the plans to your neighbours at the earliest opportunity. Doing this will enable you to take account of any potential issues before you submit a planning application, and could help to avoid objections to the proposal.   

A building warrant will be required.