Minimum = 3 metres x 3 metres
Conservatories can be built to almost any size you would like. The minimum size is 3m x 3m, however, you will need to consider a few things should you wish to have a large conservatory at the rear or side of your property. A conservatory in general is considered to be a permitted development, in other words, it doesn't need planning permission as long as it adheres to the limits below:
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 height of a single-storey rear extension of four metres.
Side extensions to be single storey with maximum height of four metres and width no more than half that of the original house.
No extension forward of the principal elevation or side elevation fronting a highway.
No verandas, balconies or raised platforms.
*The above list is not extensive, to find out more about planning permission and building regulations for conservatories and orangeries see below.