Two separate approvals sit over an orangery and they answer differently. Planning asks whether you may build it at that size in that position. Building control asks whether what you build is structurally sound and thermally adequate. An orangery frequently needs no planning permission and frequently does need building regulations approval, which is the opposite of what people expect.
Do you need planning permission for an orangery? Usually permitted development
On a house, a single storey rear extension within the householder permitted development limits needs no planning application, and an orangery is a single storey rear extension for this purpose. The limits cover how far it projects, its height, its eaves height near a boundary, how much of the garden is covered and what materials are used. They do not apply to flats or maisonettes, and they are restricted on listed buildings and in conservation areas and national parks. The technical guidance is the document that decides it.
Building control: usually required
The exemption that lets a conservatory avoid the building regulations depends on conditions including being substantially glazed in roof and walls and being thermally separated from the house. An orangery has masonry piers and an insulated flat perimeter roof, so it normally fails the substantially glazed test, and if the opening into the house is left open it fails the separation test too. The result is that most orangeries are notifiable and should end with a completion certificate.
No building regs for orangery work? Why people are told so
Orangeries are sold in the same showrooms as conservatories and the exemption is sometimes carried across in the sales conversation because it is convenient. It is worth asking the question directly and in writing: is this being built under the conservatory exemption or under a building regulations application, and who certifies it. If the answer is that no approval is needed, ask which of the exemption conditions this building meets, because that is a checkable list.
The other consents that can apply
On a terrace or semi, excavating near or building off a party wall brings the Party Wall etc. Act 1996 into it, which is notices and an award rather than a permission and which runs on its own timetable. Building over or close to a public sewer needs the water authority's agreement. On a listed building, listed building consent is separate from planning and is needed for the works themselves.
Questions people ask about orangery planning permission
Do I need planning permission for an orangery?
Often not on a house, if it stays inside the householder permitted development limits for a single storey rear extension. Flats, listed buildings and conservation areas are different and the limits are specific enough to check.
Does an orangery need building regulations approval?
Normally yes. The conservatory exemption depends on being substantially glazed and thermally separated, and an orangery with masonry piers and an insulated perimeter roof usually is not.
What if my builder says no building regs are needed?
Ask which exemption conditions the building meets, in writing. The conditions are a short checkable list, and the completion certificate is what a buyer's solicitor will ask for later.
Do I need a party wall agreement?
If you are excavating near or building off a shared wall on a terrace or semi, very likely. It is a notice and an award under the 1996 Act, separate from planning and building control, and it has its own notice periods.