Orangery vs Extension: What's the Difference and Which Should You Choose?
The terms "orangery" and "extension" are often used interchangeably in marketing but they describe structurally and aesthetically different types of addition. Understanding the real difference helps you make the right choice for your property and budget.
What Is an Orangery?
Historically, an orangery was a glazed structure used to overwinter citrus trees — popularised in British aristocratic gardens from the 17th century. In the modern residential context, an "orangery" is typically a structural brick or stone addition with a large proportion of glazing in the walls and a glazed roof structure — a lantern or full glazed roof — set above solid masonry pilasters.
Key characteristics of an orangery:
- Solid masonry perimeter walls (brick or stone) with large glazed infill panels between masonry pilasters
- A glazed roof — typically a central lantern or full glazed flat roof
- More substantial feel than a conservatory; more glass than a traditional extension
- Interior lighting quality approaching that of a conservatory but with better thermal mass
What Is an Extension?
A conventional rear extension has solid masonry or timber-frame walls with conventional insulation, a flat or pitched roof (solid), and glazing in the form of windows, doors, and possibly a rooflight or roof lantern. It is an enclosed, insulated habitable space that reads as an integral part of the house.
Key Differences
| Feature | Orangery | Extension |
|---|---|---|
| Glazing proportion | High (walls + roof) | Lower (windows/doors only) |
| Thermal mass | Good (masonry base) | Good |
| Thermal performance | Variable (depends on glazing spec) | Good with correct insulation |
| Character | Transitional — between inside and garden | Integral house space |
| Light quality | Exceptional | Good |
| Cost | Higher for equivalent floor area | Lower for equivalent floor area |
Planning Considerations
Both orangeries and extensions fall under the same planning regime — permitted development rules for single-storey rear additions apply equally to both. Conservation area and design guidance considerations also apply equally.
Thermal Performance
Modern orangeries with high-specification thermally broken glazing systems and warm roof lanterns can achieve good thermal performance. However, the large glazing area means heat gain in summer and heat loss in winter are both more significant than in a conventional extension. Careful specification and good blinds/solar control glass are essential.
Cost Comparison
A well-specified orangery is typically 20–40% more expensive than a conventional rear extension of equivalent floor area, primarily due to the cost of the glazing system, lantern, and specialist fitting. For the same budget, a conventional extension typically delivers more floor area.
When to Choose an Orangery
- When light quality and the connection to the garden are paramount
- When you want a distinctive architectural feature
- When the formal character of an orangery suits the property style (particularly period houses)
- When you are willing to invest in the premium glazing specification for the best thermal result
RCB Design & Build
RCB Design & Build delivers both conventional rear extensions and orangery-style additions — advising clients on the design, thermal performance, and cost trade-offs of each option.