An orangery sits somewhere between a conservatory and a traditional extension. It gives you a bright, glazed space that feels connected to the garden, but with more solid walls and roof than a conservatory, so it is more comfortable to use all year round. In Cornwall, where many homes enjoy sea or countryside views but face strong winds and driving rain, that balance can be very appealing.
This guide explains what an orangery is, how it compares with other options, and which planning and Building Regulations points may apply. If you already have a conservatory that is too hot in summer and cold in winter, our guide to replacing a conservatory with a proper extension covers that project in detail.
This is general guidance only. Check the current rules with Cornwall Council and Building Control for your property.
Orangery, conservatory or extension?
The terms overlap, but as a general rule:
Conservatory: mostly glazed walls on a low base, with a glazed or polycarbonate roof. Often the cheapest option, but can be hard to keep at a comfortable temperature.
Orangery: brick, block or stone piers and walls with large glazed openings, and a flat roof around the edge with one or more glazed roof lanterns in the middle. It feels more like part of the house.
Extension: mainly solid walls and a solid roof, with windows, doors and rooflights where needed. It is the most thermally efficient and flexible.
In practice, many modern orangeries are built in much the same way as a single-storey extension, with proper foundations, insulated walls and an insulated flat roof, just with more glass.
Roof lanterns and glazing
The roof lantern is the defining feature of most orangeries. Points to think about include:
Frame material: aluminium lanterns are slim and low-maintenance; timber suits some older or listed properties. Near the coast, ask about suitable coatings and fixings for salt air. Our coastal weatherproofing guide explains why this matters.
Glass: solar control and low-emissivity glass can reduce overheating and heat loss. Self-cleaning coatings are also available.
Size and orientation: a large south-facing lantern can make a room very hot in summer. Opening vents or other ventilation help.
Flat roof detailing: the upstand, insulation and drainage around the lantern must be well detailed to avoid leaks and condensation.
Do you need planning permission for an orangery?
An orangery is treated as an extension for planning purposes. Many single-storey rear orangeries can be built under permitted development if they meet every limit, which in general terms include:
A rear depth of up to 3 metres for attached houses or 4 metres for detached houses, or more under the prior approval process.
A maximum height of 4 metres, and eaves no higher than 3 metres if within 2 metres of a boundary.
Materials of similar appearance to the house, although conservatories are treated differently on this point.
Together with other extensions and outbuildings, it must not cover more than half the land around the original house.
Rights are reduced in conservation areas and the Cornwall National Landscape (formerly AONB), and do not apply to flats or maisonettes. Listed buildings will usually need consent. Our guides to permitted development rights for extensions, planning permission in Cornwall and building in an AONB or conservation area explain the details.
Building Regulations and energy rules
This is where orangeries often differ from conservatories. A conservatory may be exempt from Building Regulations if it is at ground level, under 30 square metres, separated from the house by external-quality walls, doors or windows, has no fixed heating connected to the house system, and its glazing and electrics meet the relevant requirements.
Many orangeries do not meet those conditions, usually because they have more solid wall and roof than a conservatory or are open to the house. In that case, they are likely to need Building Regulations approval like any other extension. That brings in:
Structure and foundations, including beams over large openings. Our groundworks and foundations guide explains what is involved.
Energy efficiency (Part L): walls, roof, floor, windows and rooflights must meet minimum insulation standards. Approved Document L also limits the area of glazing in an extension relative to its floor area, unless compensating improvements are shown by calculation. A heavily glazed orangery may need this calculation at design stage.
Ventilation, safety glazing and electrics, plus fire safety and drainage.
Our Building Regulations guide explains how to apply.
Designing an orangery for a Cornish home
A well-designed orangery should look as if it belongs to the house. On stone cottages, stone or rendered piers can tie it in; see our stone, rendering and lime work service. On modern homes, slim aluminium frames and render often suit. Think about where the doors open, how it links to the kitchen, and whether the garden levels need adjusting. Our kitchen extensions guide covers layout ideas that also work for orangeries.
What affects the cost of an orangery?
As very rough general guidance only, an orangery usually costs more than a conservatory of the same size and is closer in cost to a single-storey extension, typically running into tens of thousands of pounds. The main factors are:
Size, shape and the number and size of roof lanterns.
Frame material and glazing specification.
Wall materials, especially natural stone.
Foundations, ground conditions and slope.
Knocking through into the house, including steelwork.
Flooring, heating, electrics and finishes.
Only a detailed, itemised quote for your site gives a reliable figure. Our guide to reading a builder's quote explains what to check.
Frequently asked questions
Is an orangery warmer than a conservatory?
Usually, yes. With insulated walls, an insulated flat roof and good-quality glazing, an orangery is generally easier to keep comfortable than a fully glazed conservatory.
Does an orangery need Building Regulations approval?
Often, yes. If it does not meet the conservatory exemption conditions, it is treated like any other extension and is likely to need approval.
Can I add an orangery to a listed building?
Possibly, but you will usually need listed building consent and careful design. Speak to Cornwall Council's conservation officers early.
Thinking about an orangery? Talk to us
Cornish Building Company builds home extensions across the whole of Cornwall. If you are weighing up an orangery, conservatory or extension, we can talk through the options for your home. Call us on 01208 816991 or contact us to discuss your project.
