Oak Orangery
An oak orangery is the formal member of the family: a level roof with a glazed lantern at its centre, tall glazed bays between oak posts, and a brick or stone plinth that ties it to the house. A finished one typically costs £2,500 to £3,500 per m², including VAT.
£69,500 to £79,000
Typical for a 24 m² oak orangery at a detailed specification, including VAT
When an orangery is the right shape
- The house is Georgian, Victorian or otherwise symmetrical, and a steep gabled roof would fight with it.
- First-floor windows sit low over the spot, leaving no height for a pitched roof.
- You want the room to feel like part of the house in winter, with solid ceiling round the edge and light from above.
- A dining table or kitchen island will sit under the lantern.
- You are replacing a tired conservatory and want the room usable all year.
Typical oak orangery prices
| What | Typical price, including VAT |
|---|---|
| 16 m², simpleAbout 4 m by 4 m, one lantern, glazed doors on one side | £40,000 to £46,500 |
| 24 m², detailedAbout 6 m by 4 m, larger lantern, glazing on two sides | £69,500 to £79,000 |
| 35 m², detailedAbout 7 m by 5 m, open to a kitchen | £101,500 to £115,500 |
| 35 m², elaborateStone plinth, twin lanterns, full-height glazing | £115,500 to £122,500 |
A guide, not a quote. Price a different size on the cost page.
Where these figures come from
Typical national ranges for 2026, including VAT. London and the South East usually cost 20 to 40% more. Bespoke oak work can exceed £3,500 per m². A guide, not a quote.
Have a size in mind? Ask an oak framer what yours would cost.
Get a quoteWhat makes it an orangery
Three things separate an orangery from a conservatory or a garden room. The roof is flat round the perimeter, usually a warm deck finished in lead, zinc or a single-ply membrane, with a raised glass lantern in the middle. The walls carry more solid structure: masonry piers or a plinth, with oak posts standing on top. And the proportions are classical, with glazed bays of equal width and a deep fascia hiding the roof edge.
In oak, the frame is a ring of posts carrying a heavy perimeter beam. That beam does two jobs. It supports the flat roof joists, and it frames the opening for the lantern. Because every post and beam is on show from the room, the frame has to be set out so that the bays line up with doors, the lantern sits centrally, and nothing lands awkwardly in front of a window in the house wall.
Glazing and the lantern
Glass is fixed to the outside face of the oak, never squeezed between timbers. The sealed units sit against a flexible gasket and are held by oak cover strips, so the frame can shrink behind the glass without cracking it. Ask how this is done on any design you are shown; it is the detail that decides whether the room leaks in year three.
The lantern is usually made separately in painted hardwood or aluminium and dropped on to an upstand. A lantern more than about a third of the roof area lets in a lot of summer sun, so solar-control glass and at least one opening vent are worth their modest extra cost. On a north-facing wall the lantern is the main source of light and can be more generous.
Planning permission and listed houses
An orangery is treated as an extension. In England it can be permitted development if it is at the rear, single storey, no more than 4 m deep on a detached house or 3 m on any other, and no higher than 4 m, with the eaves kept to 3 m where the wall is within 2 m of a boundary. A flat roof with a lantern usually fits under those heights comfortably. The full conditions are in the government's technical guidance.
Materials must be similar in appearance to the house unless the structure is a conservatory. An oak orangery on a brick plinth that matches the house often passes; one clad wholly in timber may not. If there is doubt, a lawful development certificate settles it before you spend money on a frame. The fee in England is £274.
Listed buildings need listed building consent for any extension. An orangery is one of the easier forms to justify on a formal house, because the type has a long history on exactly that kind of building. In Scotland the depth limits are similar, the rules are tighter in conservation areas, and a building warrant is required.
Building regulations and warmth
If the orangery is open to the house, with no external-quality doors between the two, it must meet the Building Regulations in full. In England that means new walls and floor at a U-value of 0.18 W/m²K, the roof at 0.15 and glazing at 1.4 or better. Approved Document L also limits glazing to a quarter of the floor area plus the area of any openings the new room covers.
Most oak orangeries exceed that glazing limit. It is allowed, but the designer has to show by calculation that the room loses no more heat than a compliant one would, usually by improving the roof, floor or glass. This is routine. It is also a reason to appoint someone who has done it before.
A room under 30 m² can be exempt as a conservatory, but only if at least three-quarters of the roof and half the new wall area are glazed, the old external doors stay in place and the room has its own heating controls. Few orangeries with a solid roof and a lantern meet the glazing test, and one that does will be colder and used less.
What moves the price
The lantern, the roof covering and the amount of glass account for most of the gap between a simple orangery and an elaborate one. Lead costs more than a membrane. Structural glass doors cost more than oak-framed ones. A stone plinth to match a Cotswold house costs several times a brick one.
Ground conditions matter as much as finishes. Clay soil near mature trees can force deeper foundations, and an old house with shallow footings needs care where the new foundation meets it. Neither shows up in a per-square-metre figure, so treat any range as a starting point until someone has dug a trial hole.
Sources for the rules on this page
How an oak orangery is built
Survey and drawings
The house wall, floor levels and first-floor windows are measured, and the frame is drawn so the bays and lantern line up with them.
Plinth and slab
Foundations, an insulated floor slab and the brick or stone plinth are built while the oak is being cut.
Frame and roof deck
Posts and the perimeter beam go up in two or three days. The flat roof is decked, insulated and made watertight, then the lantern is lifted on.
Glass and inside work
Glazing is fixed to the face of the frame, followed by electrics, plaster, flooring and decoration.
Questions people ask
How much does an oak orangery cost?
Most fall between £2,500 and £3,500 per m² finished, including VAT, which puts a 24 m² room at £60,000 to £84,000. These are national guide figures, not quotes. The cost page lets you try other sizes.
What is the difference between an oak orangery and an oak conservatory?
A conservatory has a fully glazed roof and mostly glazed walls. An orangery has a solid flat roof with a lantern set into it and more solid wall. The orangery holds heat better and feels more like a room of the house.
Does an oak orangery need planning permission?
Not always. A single-storey rear orangery within the permitted development depth and height limits may not need an application in England, provided its materials are similar in appearance to the house. Listed buildings always need listed building consent.
Can an orangery be open to the kitchen?
Yes, and most are. Removing the wall between them needs a beam designed by a structural engineer and Building Regulations approval, and the orangery then has to meet the full insulation standards.
Will a flat roof on an oak frame leak as the oak shrinks?
It should not. The roof deck sits on softwood joists above the oak beam, and the waterproof layer is carried up the lantern upstand and over the roof edge, so movement in the frame below does not open any joint in it.
How long does an oak orangery take to build?
Allow four to five months on site and in the workshop once consents are in place: several weeks to cut the frame, a few days to raise it and two to three months to roof, glaze and finish.
Get a quote for an oak orangery
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