Planning Permission For an Orangery
Why is an Orangery that needs planning permission more expensive?
The basic answer to that question is that it’s all to do with size.
Most conservatories and orangeries in the UK can be built without getting prior panning permission from the local council if you abide by certain guidelines, and a couple of these guidelines are in respect of the area that the building can occupy.
Once you get above a certain size, irrespective of if you meet all the other requirement, you will need planning permission. SO by default you are building a bigger home extension than average.
If you build an orangery that is bigger than the average conservatory, then almost by default, it is going to be more expensive to build. You have extra materials, more labour, more time to build it and on top of that you have the cost of applying for planning permission, which in itself can cost around £600.
There are details & guides to the of orangeries on this website: orangery costs