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;
Two-storey and first floor rear extensions will not require planning permission provided they also comply with the following criteria:
- Two storey and first floor extensions are only permitted at the rear of the property, otherwise planning permission is required.
- Two-storey and first floor extensions are not permitted on properties situated on Article 2(3) land without planning permission – see above.
- The extension is not more than 3 metres deep. If a first-floor extension is being added to an existing ground-floor extension, both the ground-floor and first-floor elements must not exceed 3 metres in depth. This means you cannot add a 3-metre deep first-floor extension to an existing 4-metre deep ground-floor extension.
- The extension should be at least 7 metres away from the rear boundary of the property when measured at the closest point.
- As noted above, if any of the extension is within 2 metres of any boundary, the eaves should be no more than 3 metres high. This means that any two-storey or first floor extensions with eaves that are more than 3 metres in height should be at least 2 metres away from any boundary of the property, otherwise planning permission is required. Upper floor windows situated in side elevations of the extension should be obscure-glazed and fixed shut unless the parts of the window which can be opened are more than 1.7 metres above the finished floor level of the room they serve. See also Property Alteration Overview for more potential restrictions: https://planningaid.zendesk.com/hc/en-us/articles/203210341-Property-Alterations-Overview