Orangery vs Conservatory: Structural, Thermal and Cost Differences Explained
Beyond the marketing labels: how the two structures are actually built differently, what that does to heat loss and daylight, and what genuinely drives the cost gap between them.
In this guide
Our guide to which space you need covers how to choose between a conservatory, orangery, extension or garden room by use. This one goes one level deeper on just two of those options: what physically differs between an orangery and a conservatory, why that changes how the room feels through the year, and where the real cost differences come from.
Structural differences
A conservatory is typically defined by having a glazed roof covering at least the majority of the roof area, with the walls below often mostly glazed as well, sitting on a low dwarf wall or directly on the foundation. An orangery, by contrast, is usually built with more solid brick or masonry walling around most of its perimeter, a flat or low-pitched roof with a central glazed lantern rather than a fully glazed pitched roof, and often internal pillars or a box gutter detail where the roof meets the walls. The practical effect is that an orangery reads architecturally as closer to a solid extension with a feature roof light, while a conservatory reads as a predominantly glazed garden room.
Neither term has a fixed legal definition — the Planning Portal treats conservatories as falling within the same householder extension rules as any other home addition, and in practice an orangery is assessed under the same planning and Building Regulations regime as a conservatory or a conventional extension — the physical build-up, not the sales name, is what a planning officer or building control surveyor actually looks at.
Thermal performance and Building Regulations
Because an orangery has proportionally less glazed roof area and more solid, insulated wall and roof construction, it generally loses heat more slowly than a fully glazed conservatory of the same footprint, and it is usually easier to keep within normal Building Regulations thermal requirements without needing to rely on the more limited exemptions available to some conservatories. The relevant national guidance on thermal performance for extensions sits within the Approved Documents to the Building Regulations, specifically the document dealing with conservation of fuel and power; a building control body or a competent designer can confirm exactly how it applies to a specific room.
Glazing specification affects both structures, just to different degrees. The Energy Saving Trust’s guidance on energy efficient windows and doors explains that moving from single to double or triple glazing reduces heat loss, draughts and condensation by creating an insulating gas-filled gap between panes — relevant to an orangery’s glazed lantern and a conservatory’s glazed walls and roof alike, though a conservatory with a larger glazed area has proportionally more to gain, or lose, from the specification chosen. See our dedicated glazing explainer for how to read a U-value or solar factor on a quote.
What actually drives the cost gap
We don’t publish price ranges here because they date quickly and vary by region, installer and specification — use our guide to comparing quotes for that. What we can set out is which factors tend to push an orangery’s price above a similarly sized conservatory’s, structurally rather than by brand:
- More brickwork and foundations. Solid perimeter walls need a foundation designed for masonry load, not just a lightweight glazed frame.
- A more complex roof. A flat or low-pitch roof with a glazed lantern, box gutters and internal pillars involves more structural design and labour than a single glazed pitched roof.
- Bespoke glazing shapes. A roof lantern is typically a made-to-measure item rather than a standard glazed roof panel run.
- Internal finishing. Solid walls are usually plastered and finished to match the house internally, adding a finishing trade that a mostly glazed conservatory doesn’t need in the same way.
None of this means an orangery always costs more in every case, or that a conservatory is always the budget option — a large bespoke conservatory with premium glazing can cost more than a small, simple orangery. Ask any installer to itemise the quote by these components so you can compare like with like.
Which one needs which approvals
Both are generally assessed under the same householder permitted development rules and the same Building Regulations regime as any other extension — see our guide to how permitted development works for the mechanism. Neither the word “orangery” nor “conservatory” on a brochure changes which regime applies; the actual dimensions, materials and thermal design do.
FAQs
Is an orangery always warmer than a conservatory?
It tends to lose heat more slowly because more of its envelope is solid, insulated construction rather than glass, but the specific glazing, insulation and heating design of each individual room matters more than the label alone.
Do orangeries need planning permission more often than conservatories?
Not inherently — both are usually assessed under the same householder extension rules. Size, height, boundary proximity and the property’s planning history are what determine the outcome, not which of the two terms is used.
Suggested component
A side-by-side structural diagram toggle (roof build-up, wall type, glazing ratio) rather than a single price comparison table.
Related guides
Conservatory styles
Orangeries
Garden rooms & offices
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