Installed uPVC prices, size by size, from sourced 2026 guides: a 3m x 3m lean-to from £5,000, mid-size builds £7,000 to £17,500 depending on style, and orangeries £20,000 to £50,000 and up. Every figure below carries its source and date, the differences between the guides included; no installer behind this page and no lead selling.
| Size | Lean-to (uPVC) | Victorian | Edwardian |
|---|---|---|---|
| 3m x 3m (9 m²) | £5,000 to £9,000 | £8,000 to £12,500 | £8,500 to £13,500 |
| 3m x 4m / 4m x 3m (12 m²) | £6,000 to £10,500 | £9,000 to £14,000 | £9,500 to £15,000 |
| 5m x 3m (15 m²) | £7,000 to £12,000 | £10,000 to £16,000 | £10,500 to £17,000 |
| 4m x 4m (16 m²) | £7,500 to £12,500 | £10,500 to £16,500 | £11,000 to £17,500 |
| 5m x 4m (20 m²) | £8,500 to £14,500 | £12,000 to £19,000 | £12,500 to £20,000 |
| 6m x 4m (24 m²) | £10,000 to £17,000 | £14,000 to £22,500 | £15,000 to £24,000 |
Installed, including frames, glazing, a standard base and VAT (BestBuilders, August 2026, regional cost model with quarterly review). The second benchmark sits higher: RenovationCosts' trade data puts a typical full project at £18,360 to £24,840, largely because real jobs add groundworks (£1,800 to £4,800) and extras on top. Read both as the honest spread, not as a contradiction to pick a side in.
Planning follows the same permitted development rules as any extension; the free planning permission check walks your situation question by question. The building regulations exemption is the quiet reason a conservatory prices below an extension. Approved Document L (2021 edition with the 2023 amendments, paragraph 0.14) sets its conditions: ground level, a floor area of at most 30 square metres, glazing to Part K, the wall, door or window between house and conservatory kept or replaced like for like, and the heating of the house not extended into it. The Planning Portal says the same in plainer words. A roof condition is not on that list, and that is where the confusion starts: the regulations have not defined a conservatory since 2010, so building control works with the LABC definition of at least 75 percent translucent roof and 50 percent translucent walls. Fit a solid roof, remove the dividing doors or extend the heating, and the room is treated as an extension.
A mid-range single-storey rear extension runs £48,000 to £72,000 in our validated price data, the same source as the calculator. The conservatory buys light and floor space for less; the extension buys an unrestricted, fully insulated room. The full comparison lives in the extension guide and extend or move; and when quotes arrive, the quote check reads them line by line, because quotes for identical specs vary 20 to 30 percent between firms (BestBuilders).
Sources: BestBuilders, Conservatory Cost by Size & Type (updated 21 August 2026, regional cost model, quarterly review) (opened 30 August 2026); RenovationCosts.co.uk, Conservatory Cost UK (trade benchmark data, updated 2 May 2026) (opened 30 August 2026; page offline when checked on 27 September 2026, figures as read on the opening date); Planning Portal, Conservatories: building regulations and planning permission (opened 30 August 2026); Approved Document L, Conservation of fuel and power, Volume 1: Dwellings (2021 edition incorporating 2023 amendments), paragraph 0.14 (opened 27 September 2026); LABC technical guidance note, Guidance on application of Part L to conservatories attached to existing dwellings (copy hosted by LABSS) (opened 27 September 2026); LABC Front Door, I want to replace my conservatory roof, what should I know? (opened 27 September 2026). The extension comparison comes from our validated 2026 UK price data.
£5,000 to £9,000 installed as a uPVC lean-to, £8,000 to £12,500 in Victorian style and £8,500 to £13,500 in Edwardian style, including frames, glazing, a standard base and VAT (BestBuilders, August 2026). The bottom of each range is a polycarbonate roof, the top an A-rated glass roof. Note the second benchmark: RenovationCosts' trade data puts a typical full project at £18,360 to £24,840, because real jobs often add groundworks (£1,800 to £4,800) and extras on top of the base tables.
Substantially, and here both sides come from checkable data: the conservatory tables above run £5,000 to £24,000, while a mid-range single-storey rear extension is £48,000 to £72,000 in our validated price data.
The gap has a legal reason: a conservatory of at most 30 square metres at ground level, kept separate from the house and off its heating, is exempt from the energy efficiency requirements of the building regulations (Approved Document L, paragraph 0.14). Remove the dividing doors, extend the heating into it or swap the glazed roof for a solid one, and building control treats it as an extension, with the regulations and the price tag that belong to one.
Usually not: a conservatory follows exactly the same permitted development rules as any extension (Planning Portal). Single storey, behind the principal elevation, height and projection within the limits, and no more than half the garden covered. Listed buildings and conservation areas are stricter. Check your own situation in minutes with the free planning permission check, question by question.
On a new build a solid tiled roof adds £4,000 to £8,000 over polycarbonate; retrofitting one on an existing conservatory runs £4,000 to £12,000 depending on size and whether the frames need strengthening. Two warnings from the sources.
Replacing a translucent roof with a solid one needs a building regulations application (LABC), because building control only counts a structure as an exempt conservatory when at least 75 percent of its roof and 50 percent of its walls are translucent. And building control inspects whether the existing frames and base can carry the extra load, so have that checked before you commit.
BestBuilders says it plainly: quotes for identical specs routinely vary 20 to 30 percent between firms. The RenovationCosts bands say the same in their own way: the top of each band is close to double the bottom (a small lean-to from 9,600 to 18,000), and foundations vary five-fold with ground conditions. The defence is boring and effective: three like-for-like quotes with the frame system, roof type and base itemised, and a check of the winning quote line by line before signing.