Under new regulations which came into effect from 1 October 2008 adding a conservatory to your home is considered to be a 'permitted development', not needing an application for planning permission, subject to the following limits and conditions:
•No more than half the area of land around the 'original house'* would be covered by additions or other buildings.
•No extension forward of the principal elevation or side elevation fronting a highway.
•No extension to be higher than the highest part of the roof.
•Maximum depth of a single-storey rear extension of three metres for an attached house and four metres for a detached house.
•Maximum height of a single-storey rear extension of four metres.
•Maximum depth of a rear extension of more than one storey of three metres including ground floor.
•Maximum eaves height of an extension within two metres of the boundary of three metres.Maximum eaves and ridge height of extension no higher than existing house
•Side extensions to be single storey with maximum height of four metres and width no more than half that of the original house.
•Roof pitch of extensions higher than one storey to match existing house
• No verandas, balconies or raised platforms.
•On designated land* no permitted development for rear extensions of more than one storey; no cladding of the exterior; no side extensions.
•Where work is proposed to a listed building, listed building consent may be required.
* The term 'original house' means the house as it was first built or as it stood on 1 July 1948 (if it was built before that date). Although you may not have built an extension to the house, a previous owner may have done so.
* Designated land includes national parks and the Broads, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites.