This guidance reflects temporary increases to the size limits for single-storey rear extensions that must be completed by 30th May 2019, and the associated neighbour consultation scheme. Adding a conservatory to your house is considered to be permitted development, not needing an application for planning permission, subject to the limits and conditions listed below.
No more than half the area of the 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.
Single-storey rear extension must not extend beyond the rear wall of the original house* by more than three metres if an attached house or by four metres if a detached house.
In addition, outside Article 2(3) designated land* and Sites of Special Scientific Interest the limit is increased to 6m if an attached house and 8m if a detached house until 30 May 2019.
These increased limits (between 3m and 6m and between 4m and 8m respectively) are subject to the prior notification of the proposal to the Local Planning Authority and the implementation of a neighbour consultation scheme. If objections are received, the proposal might not be allowed.
Maximum height of a single-storey rear extension of four metres.
Extensions of more than one storey must not extend beyond the rear wall of the original house* by more than three metres or be within seven metres of any boundary opposite the rear wall of the house.
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.
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 Broads, Areas of Outstanding Natural Beauty, Conservation Areas and World Heritage Sites.
For more details and up to date advice, please click here: http://www.planningportal.gov.uk/permission/commonprojects/conservatories/