These two are often confused and the following notes are intended for guidance only, and are general requirements for all areas. Please consult the relevant local authority for any specific requirements for the area concerned.

On some new housing estates the developers sometimes insert a clause in the deeds requiring their permission to extend the house. This should be checked and in some cases a small fee may be charged to obtain permission.

DEFINITION OF A CONSERVATORY

According to the Department of the Environment, a conservatory is defined as "A building that has not less than seventy five percent of its roof area made of translucent material, and not less than fifty percent of its wall area made of glass."

PLANNING PERMISSION

This is the decision as to whether or not you can build a particular structure in a particular place, and it is concerned with the visual impact and size of the structure. Not the structural integrity of the construction. 

Specific planning permission is not normally required if the following guidelines are met :-

1. A detached or semi-detached dwelling may be extended without planning permission (subject to the following conditions) by up to 70m³ or 15% of the volume of the original house, whichever is the greater (to a maximum of 115m³).
2. A terraced house (or a house in a national park, an area of outstanding natural beauty, a conservation area or other specially designated area) may be extended up to 50m³ or 10% of the volume of the original house.
3. The overall height of the conservatory must not exceed 4m when the conservatory is less than 2m from any boundary. If greater than 2m from any boundary, the height of the conservatory may equal the height of the house. 
4. The conservatory is used solely for domestic purposes.
5. The roof and walls of the conservatory are glazed with translucent or transparent materials with safety glazing at low level (see definition of a conservatory above). 
6. No part of the conservatory should be closer to the highway than the nearest part of the original house unless there would be at least 20m between the house (as extended) and the highway.

Application for planning permission IS required if :-

1. The proposed conservatory is on any wall fronting the highway. Note: Highway includes all public footpaths, bridle ways and byways.
2. The property is a listed building or in a conservation area.
3. The property is non-residential or anything other than a single dwelling.
4. The conservatory is higher than any part of the original building.
5. The conservatory and other additions to the original house exceed 50% of the total area area of the garden within the boundaries of the property.
6. Eaves, fascias, foundations or guttering encroach over the boundaries of the property.

BUILDING REGULATIONS

These are the construction and performance standards which, if followed, allow a structure to be built. They relate to the structural integrity of the construction and not its location. It should be noted that Building Regulations in England and Wales are different to those in Scotland and Northern Island. Check with local authorities for the existence of any local by-laws which may need to be considered. 

A conservatory is usually exempt from any Building Regulation control provided it meets the following requirements :-

1. The conservatory is used solely for domestic purposes.
2. The floor area is less than 30m² (internal floor).
3. The roof and walls are glazed with translucent or transparent materials with safety glazing at low level.
4. The conservatory is built at ground level
5. The conservatory contains no sleeping accommodation.
6. The construction of the conservatory does not effect the existing drainage system.

If a conservatory does not require Building Regulation approval and the conservatory is situated within 1m of the boundary, then the wall of the conservatory adjacent of the boundary should be constructed of materials with limited combustibility which meet fire regulations to approved document B of the Building Regulations 1992.