A single-storey side would not require permission provided:
- The extension would not be between the house and a highway, i.e. if the house is on a corner plot and an extension is proposed on the side facing the highway
- Following the extension the total area of ground covered by buildings within the curtilage of the house (other than the original house) would exceed 50% of the total area of the curtilage (excluding the ground area of the original house);
- All parts of the extension would be lower than the highest part of the roof of the original house (this would normally only be an issue when a bungalow was to be extended)
- The eaves of the extension would be lower than the eaves of the original house (this would normally only be an issue when a bungalow was to be extended)
- The extension would be no more than 4 metres high
- If the extension is within 2 metres of the boundary the eaves would be less than 3 metres high
- The extension would exceed half the width of the original dwelling. On a detached house, provided the plot can accommodate them, it is possible to build a “half-width” single-storey extension on each side
- It does not include the construction or provision of a verandah, balcony, raised platform, microwave antenna, chimney, flue or soil and vent pipe;
- Unless it is a conservatory it is built using external materials similar in appearance to those on the existing house
- If the property is in on Article 2(3) land, i.e. 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 is clad in stone, artificial stone, pebble dash, render, timber, plastic or tiles.