You should always check to see if planning permission is required.
You won’t always need Planning Permission when building a Conservatory, but this depends on a number of things, including;
• If the conservatory is closer to a public highway than the original building was, planning permission may be required.
• How big the Conservatory will be in comparison to the size of the main building
• Whether the main building has been previously extended
• The height and volume of the Conservatory
• Whether the main building is listed
• Whether the property is in a conservation area
This site had some really good information and guides
• Volume calculator for your conservatory
• Costs for planning permission
• A facility to start a planning application online (only available for some local authorities)
Building Regulations
There are a number of classes of new buildings or extensions of existing buildings that do not need Building Regulations approval. Amongst those are conservatories and porches, which are exempt from the Regulations provided that they meet the following criteria:
They are built at ground level
They are single storey
They have a floor area not greater than 30m²
The glazing accords with Part N of the Regulations i.e. protection against impact
Any electrical work that has its own ring main or is extended from a room classed as a special location i.e. kitchen complies with Part P of the Building Regulations – Electrical Safety
For the purposes of deciding whether the addition of a conservatory to an existing home requires Building Regulations approval, there is no definition of what a conservatory is. If however, no separation will remain between the existing home and the new conservatory it is likely that the conservatory will be judged as an conventional extension of the home, for which Building Regulations approval will be required with roof insulation cost.
Glazing
The Building Regulations require that glazing with which people might collide, should be such that the risk of being injured is reduced.
The typical provision for glazing in a porch or conservatory will be to ensure that glazing in the following positions:
In windows, within 800mm of floor level (or 1500mm if within 300mm of a door); and
In doors, within 1500mm of floor level should react in one of the following ways on impact:
Break in a way which is unlikely to cause injury
Resist impact without breaking
Be shielded or protected from impact
Although not likely to be a requirement of the Building Regulations, it is advisable to ensure that a conservatory does not make escape (in case of fire) from a window on the storey above more difficult.