Planning Permission has always been a subject that has eluded many renovators (and designers) but even in London today, depending on what works you are planning, you may be surprised to find you will not need planning permission. Permitted Development (PD) rights entitle homeowners to make changes to their home without needing planning permission and include a number of renovations, including extensions. This is not to say you will never need planning permission for an extension (heavens no!) as there are a number of limitations and exceptions to the rule, for example, if you live in a Conservation area or a Listed building.

For listed buildings, all alterations (including internal ones) require consent. Depending on the size of your extension, you may require planning permission and listed buildings consent.

However, in general, planning permission will not be required for an extension as long as

  • The extension will not exceed 50% of the total land area around the original house - this calculation should include sheds and other buildings.
  • Single storey side extensions do not have a width greater than half the width of the original house
  • Single storey side extensions do not exceed 4m in height
  • Extensions within two metres of the boundary are built no higher than 3m
  • Single storey rear extensions do not extend beyond the rear of the original house by more than 3m for an attached house, or 4m for a detached house
  • Single storey rear extensions do not exceed 4m in height
  • Exterior materials are similar in appearance to those of the existing house
  • The roof pitch of extensions more than one storey should match that of the existing house
There are a number of other details that apply to extensions of more than one storey.
All extensions will require Building Regulations approval, which ensure that minimum design and construction standards are being met and cover things such as fire safety, insulation, drainage and access. Your interior designer or architect can help you submit a Full Plans Submission, or you can do this yourself. A building inspector will visit the site at various stages of the project. Alternatively, you can submit a Building Notice, giving the council 48 hours notice that you intend to start works. A building inspector will visit the site at various stages during the project and you will need to be prepared to correct work that does not meet the regulations.

For more information on Permitted Development, visit

Homebuilding and Renovating Magazine