The following permitted development restrictions apply to all extensions and alterations to a dwellinghouse:
- Residential properties created as a result of prior approval (e.g. change of use from office to residential) do not benefit from householder permitted development rights. All new extensions will therefore require planning permission.
- No more than 50% of the curtilage of the dwelling should be covered by buildings or extensions (excluding the original dwelling).
- No extension should exceed the height of the highest part of the roof of the existing dwelling.
- The eaves height of the extension should not exceed the eaves height on the existing dwelling.
- If the extension is within 2 metres of your boundaries, the eaves height should not exceed 3 metres high;
- The extension should not include or incorporate a veranda, balcony, raised platform, microwave antenna, chimney, flue or soil and vent pipe or alterations to any part of the roof of the dwelling.
- If the property is in on Article 2(3) land, i.e. situated within a National Park, an Area of Outstanding Natural Beauty, a Conservation Area, an area designated under s41(3) of the Wildlife and Countryside Act 1981, the Norfolk Broads or a World Heritage Site, no part of the original or extended house should be clad in stone, artificial stone, pebble dash, render, timber, plastic or tiles.
- Unless it is a conservatory, the extension should be built using external materials similar in appearance to those on the existing house;
Single-storey rear extensions will not require planning permission provided they also comply with the following criteria:
- The extension would not extend more than 3 metres from an original rear wall on a terraced or semi-detached house; or 4 metres on a detached house;
- The extension does not exceed 4 metres in height;
Larger Home Extensions:
There are also provisions under permitted development rights to build larger rear extensions. This would allow a rear extension of up to 6 metres in length on a terraced or semi-detached house; or an extension up to 8 metres on a detached house.
However, before constructing the extension you are required to notify the Local Planning Authority through the process known as ‘prior approval’. This usually involves confirming in writing the length, roof height and eaves height of the proposed rear extension together with a plan of the site showing the proposed extension, the addresses of adjoining neighbouring properties and your contact details.
The Local Planning Authority is then required to consult adjoining neighbouring properties for a period of 21 days before any decision can be made. Should a neighbour object to the proposals the Local Planning Authority is required to consider the impact of the proposed extension on neighbouring residential amenity e.g. loss of daylight, overlooking, overshadowing. Local Planning Authorities normally advise discussing your proposals with your neighbours before notifying the Council.
If you do not enter into this process before constructing a larger home extension then planning permission is automatically required. You cannot enter into the prior approval process retrospectively.
See also Property Alteration Overview for more potential restrictions: https://planningaid.zendesk.com/hc/en-us/articles/203210341-Property-Alterations-Overview