Orangery vs conservatory

Look at the roof. If you can see sky across the whole of it, you are in a conservatory. If there is a plastered ceiling around the edge with a glazed lantern standing up from the centre, it is an orangery. The walls follow the same logic: a conservatory is frames on a low wall, an orangery has brick or rendered piers at the corners and often between the windows.

Planning law draws no line between them. Building regulations do: the Planning Portal’s conditions for the conservatory exemption include at least three quarters of the roof and half of the new wall area being glazed or translucent. Most orangeries fall well short on the roof.

An orangery costs £850 to £3,000 per m² to build in 2026, depending mostly on the frames. A conservatory of the same footprint costs less, because a glazed roof on light frames needs far less structure than an insulated deck, a ring beam, masonry piers and a lantern.

Conservatory prices vary so much between makers and systems that we do not publish a national figure for them. The fair comparison is two quotes for the same footprint on the same visit. What we can show is where an orangery sits against the other room people price at the same time, a conventional single-storey extension.

This is where the extra money goes. A glazed roof loses heat quickly on a winter night and gains it quickly on a July afternoon, however good the glass. An orangery roof is mostly insulation. The lantern gives you daylight in the middle of the room without turning the whole ceiling into a radiator.

Glare matters more than people expect. Under a fully glazed roof a television or a laptop screen is hard to use for much of the day. The plastered border of an orangery ceiling shades the edges of the room and gives you somewhere to put downlights.

Rain is the third difference. On polycarbonate it drums; on a glass roof it is noticeable; on an insulated deck you barely hear it.

Planning treats the two identically. Each is a single-storey extension, and either can go up without an application inside the householder allowance: in England, a depth of 4 m on a detached house or 3 m on a semi or terrace, and 4 m overall height.

Building regulations are where they part. A conservatory with less than 30 m² of floor, built at ground level, mostly glazed, separated from the house by external-quality doors and with independent heating is exempt from most of the regulations. An orangery is not, because its roof is mostly solid. Expect building control approval whether or not it opens into the house.

That is a cost, in fees and in insulation to current standards, and also a benefit: you finish with a completion certificate for a habitable room, which a buyer’s solicitor will ask for. Open a conservatory to the house and it loses its exemption too, so the gap narrows for open-plan rooms.

If the base and dwarf walls are sound, some of the old conservatory can stay, and an insulated flat roof with a lantern goes on existing or new frames. It is usually cheaper than starting again, but it is not always possible. Conservatory frames were sized to carry a light roof, and old foundations are often shallower than a builder would dig today.

A solid roof also ends the building regulations exemption, so building control will want to see that the structure can take the load. Ask any builder who proposes re-roofing how they will show that, and who applies for approval.

Choose the conservatory if the budget is tight, the room will be closed off from the house, and you want a garden room for spring to autumn more than a living room.

Choose the orangery if the room is going to hold a kitchen, a dining table or a sofa you sit on in January. The higher price buys a room that estate agents will measure as part of the house.