6m x 4m Conservatory Cost UK 2026: £22,000 to £40,000
uPVC from £22,000, hardwood from £40,000, orangery from £42,000. Twenty-four square metres, three to four weeks on site, the size at which an orangery often becomes the better spec.
Updated May 2026. FMB, Checkatrade, Homebuilding and Renovating, Anglian published price guides.
6m x 4m Prices by Style (2026)
| Style | uPVC | Aluminium | Hardwood |
|---|---|---|---|
| Lean-to (6m x 4m) | £22,000 - £28,000 | £28,000 - £36,000 | £38,000 - £48,000 |
| Edwardian | £24,000 - £31,000 | £31,000 - £40,000 | £42,000 - £52,000 |
| Victorian (5-facet) | £28,000 - £36,000 | £36,000 - £46,000 | £48,000 - £60,000 |
| Gable-end | £30,000 - £38,000 | £38,000 - £48,000 | £50,000 - £62,000 |
| P-shaped (6x4 + 2x3 wing) | £32,000 - £42,000 | £42,000 - £54,000 | £56,000 - £70,000 |
| Orangery | £42,000 - £52,000 | £48,000 - £60,000 | £62,000 - £78,000 |
Includes supply, install, base, glass roof, basic electrics. Excludes flooring, structural beam for knock-through, warm roof upgrade, planning fees, VAT. Source: FMB 2026, Anglian price guides, Checkatrade.
Why 6x4 Is the Crossover Point
Twenty-four square metres is the size at which a conservatory stops being the lower-cost alternative to a full extension and starts overlapping with it. Compare a 6x4 conservatory at £22,000 to £40,000 with a 6x4 single-storey rear extension at £36,000 to £60,000. The cost gap that justified picking a conservatory at smaller sizes (3x3, 4x3) narrows to 30 to 40% rather than 50 to 70%. Once you add the warm roof upgrade, structural knock-through, and planning fees that a usable 6x4 conservatory typically needs, the gap closes further.
The case for the conservatory at this size rests on three factors. Speed: a 6x4 conservatory completes in three to four weeks; a comparable extension takes 12 to 20 weeks. Disruption: the conservatory builds offline from the existing structure; the extension requires structural opening and significant internal works. Style: the all-glazed aesthetic of a Victorian or gable-end conservatory is not replicable in a traditional extension and is the right answer for owners who want the conservatory look specifically.
The case against rests on long-term value. Estate agent surveys consistently show that an extension at this footprint adds 10 to 18% to property value, while a glass conservatory adds 4 to 8%. An orangery sits between at 8 to 14%. For 6x4 builds intended as permanent family-room additions, the orangery is the option that captures most of the conservatory aesthetic while delivering closer-to-extension value uplift. The £15,000 cost premium for the orangery often returns 1.5x to 2x that on resale, making it the better long-term spec.
Structural Beam: The 6 Metre Span Problem
A 6 metre roof span exceeds the unsupported limit for standard uPVC conservatory ridge systems. Most installers cap the uPVC ridge at 4.5 to 5 metres before requiring intermediate support. The solutions at 6x4: a reinforced aluminium-cored ridge (premium £1,000 to £2,500 over standard PVC ridge) which works to about 5.5 metres comfortably; a structural ridge in steel or aluminium box section (£1,500 to £3,500 supplied) for spans up to 7 metres; or a central tie bar visibly crossing the ceiling at the apex (£200 to £500 but visually compromises the open feel).
For a 6x4 with a glazed lantern in an orangery configuration, the lantern itself provides structural support to the flat roof, so the span issue is solved differently. The flat perimeter roof spans only 1 to 1.5 metres between the brick pillars and the lantern frame, which is well within standard timber joist capacity. This is one structural reason why orangeries are often the cleaner engineering solution at 6x4 and larger sizes.
When the conservatory involves a knock-through to the existing kitchen behind, a steel beam takes the load of both the existing first-floor structure above and the conservatory roof ridge. The beam runs the full width of the opening (typically 4 to 6 metres) and requires structural engineer calculations (£300 to £700), building control approval (£400 to £900), and installation by an experienced builder (£2,500 to £4,500 including making good). Total knock-through and structural cost on a 6x4 build: £6,000 to £10,000 over and above the conservatory base price.
The Planning Permission Process at 6x4
For most attached houses, a 6x4 conservatory falls outside permitted development for one of two reasons: the 4 metre projection exceeds the 3 metre standard PD limit (the prior approval route applies up to 6 metres), and the 24 m² footprint usually breaches the 50% garden coverage limit on terraced and small semi-detached gardens. The route is typically full planning permission via your local authority.
Process: submit a full planning application via the Planning Portal. Fee in England is £206 for a householder application (2026 rate). The application requires site plans, elevation drawings, a design and access statement (often required, depends on local validation rules), and sometimes a heritage impact assessment if in a conservation area or near listed buildings. Validation by the council takes 1 to 2 weeks; the decision period is then 8 weeks for straightforward applications.
Approval rates for householder conservatory applications run roughly 88% nationally (Department for Levelling Up planning statistics, 2024). Refusals are usually triggered by neighbour amenity objections (loss of light, overlooking) or design issues (incongruous appearance, scale relative to dwelling). Where a refusal is anticipated, working with a planning consultant (£400 to £1,500 for a straightforward application) before submission usually identifies the risks and adjusts the design to mitigate them. Where a refusal happens, the appeal route via the Planning Inspectorate takes 8 to 20 weeks and is free to applicants but typically requires legal or consultant support (£1,500 to £4,000).
6m x 4m Conservatory Cost Calculator
Enter 6 in width and 4 in depth for a 6x4 estimate.
Conservatory Cost Calculator
Enter your details for a 2026 price estimate. Based on FMB, Checkatrade, and Which? data.
Floor area: 12.0 m2
Estimated Total Cost
£14,800 to £30,300
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Cost Breakdown
Excludes: flooring, heating, furniture, VAT where applicable, planning fees. VAT is typically 20% on labour and materials.
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6m x 4m Conservatory FAQ
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Related Pages
5m x 4m (20 m²)
Down a size. Family-room sweet spot. £18,000 to £30,000.
8m x 4m Bespoke (32 m²)
Up a size. Over BR threshold. £28,000 to £60,000+.
Orangery at 6x4
The premium spec: usually the better-value answer at this footprint. From £42,000.
vs Single-Storey Extension
Why the conservatory price gap narrows at 6x4 and what changes the calculus.
Planning Permission
Full planning application step-by-step: fees, timelines, refusal rates, appeal routes.
Warm Roof
Why warm roof is essentially mandatory at 6x4 for year-round usability.