Orangeries vs Conservatories in London: What's the Difference and Which Is Better?

A traditional conservatory is a glazed structure — walls primarily of glass (typically UPVC or aluminium-framed), roof entirely of glass (a glazed roof system), and typically a dwarf wall of masonry to approximately 600mm height below the glazed walls. The proportion of glazed wall and roof area in a conservatory is typically 75%+ of the total envelope area. A traditional orangery differs in that: the walls are primarily masonry or rendered brick (not glazed), with windows set into the brick walls in a conventional way; the roof is typically a flat or low-pitch lantern roof — a glazed lantern set within a flat or low-pitch solid roof structure — so the proportion of glazing is lower and the proportion of masonry and insulated roof is higher; and the overall thermal and structural quality of the orangery is significantly closer to a conventional extension than a conservatory is. In planning and Building Regulations terms, what matters is the proportion of the structure that is transparent (glass or polycarbonate): the GPDO (which provides the permitted development framework for extensions) defines a 'conservatory' for planning exemption purposes as an extension where: the roof is predominantly translucent; the extension is thermally separated from the house by a door, wall, or window; and the extension complies with the GPDO limits for extensions (same area and height limits apply). An orangery with primarily masonry walls and a solid roof with a glazed lantern is typically treated as a conventional extension for planning and Building Regulations purposes — not as a conservatory.

Conservatories (as defined by the GPDO — predominantly translucent roof and walls) that comply with the standard extension permitted development limits (no more than 3m projection from a semi-detached house, not covering more than 50% of the curtilage area, maximum 4m height, not forward of the principal elevation) are permitted development — no planning permission required. The thermal separation requirement (a wall, door, or window between the conservatory and the main house) has been removed as a planning requirement as of April 2019 — the thermal separation requirement now falls under Building Regulations Part L only. Orangeries — where the walls are primarily masonry and the roof structure is a solid flat or low-pitch roof with a glazed lantern — are treated as conventional extensions for planning purposes. They must comply with the same PD limits as a rear extension: for a semi-detached London house, a maximum projection of 3m beyond the rear wall of the original house (or up to 6m under the prior approval / Neighbour Consultation Scheme if the neighbours do not object and the LPA does not require prior approval). Conservation area restrictions: in a London conservation area, the planning officer is likely to require that a prominent conservatory or orangery does not harm the character of the conservation area — a large glazed conservatory on the rear of a Victorian terrace in a conservation area may require planning permission even if it would otherwise be permitted development, under an Article 4 Direction removing the PD right for rear extensions in that conservation area. The glazing should be appropriate to the character of the property — aluminium is generally acceptable in conservation areas, UPVC less so.

Building Regulations Part L (Conservation of Fuel and Power) is the key regulatory difference between a true conservatory and an orangery or conventional extension: A conservatory that meets all three of the following criteria is exempt from Part L thermal performance standards: (1) it is built at ground level; (2) the floor area does not exceed 30m²; and (3) the glazing (roof and walls) meets the standards for controlled fittings (windows and rooflights) under Part L (Uw ≤ 1.4 W/m²K for windows and roof lights). If any of these criteria are not met (e.g., conservatory over 30m², or with a polycarbonate roof that cannot meet the 1.4 W/m²K roofslight standard), Part L compliance is required — the conservatory must meet insulation standards as if it were a conventional extension. An orangery — because it has primarily masonry walls and an insulated flat roof with a lantern — is not a conservatory under Building Regulations and must comply with Part L1B fully: wall U-value target 0.18 W/m²K (achievable with 100mm PIR); roof U-value target 0.15 W/m²K (achievable with 130mm PIR warm roof); floor U-value 0.15 W/m²K (achievable with 100mm PIR under screed); glazed lantern U-value ≤ 1.4 W/m²K; and thermal bridging at junctions to be detailed in accordance with approved junction details. The heating provision difference: a true conservatory that is Building Regs exempt does not need to meet Part L standards, but also cannot be counted as a 'habitable room' under Part L — if the conservatory is to be used year-round as a living space (not just a seasonal garden room), the Building Regulations inspector will typically classify it as a habitable extension subject to Part L. An orangery, meeting full Part L compliance, can be classified as a habitable room without restriction.

The cost differential between a conservatory and an orangery is significant — primarily because the orangery involves more masonry construction, higher-specification roofing, and more complex structural design. Indicative costs for London in 2025: Basic UPVC conservatory, 15-20m², polycarbonate roof, standard specification, self-build supply-only (homeowner arranges contractor): £8,000-£15,000 supply only, £15,000-£25,000 supply and fit including groundworks and electrical connection. Aluminium-framed glazed conservatory, 20-25m², self-cleaning glass roof panels, standard lantern section: £20,000-£40,000 supply and fit including groundworks. Solid-roof conservatory (traditional conservatory frame, aluminium-framed, but with a solid insulated tiled roof replacing the glazed roof — a popular product in the UK retrofit market): £25,000-£50,000 for 20-25m², depending on specification. Orangery (masonry walls, flat roof with large central glazed lantern, aluminium bifold doors to garden, full Part L compliance, standard specification internally): £35,000-£60,000 for 20-25m², including Building Control, groundworks, electrical, plastering, and finishes. Bespoke orangery (brick and stone construction, hardwood-framed lantern, heated stone floor, high specification): £60,000-£100,000+ for 25-30m². Added value: a well-designed, thermally compliant orangery or solid-roof garden room addition that genuinely adds a habitable year-round room adds more to a London property's sale value than a basic UPVC conservatory — the latter is often discounted by buyers as non-habitable and thermally poor. Estate agents in London typically value a good orangery addition as adding 5-8% to a property's value, compared with 2-4% for a basic glazed conservatory.