Garden Room vs Conservatory Cost UK 2026
Garden room £15,000 to £40,000, conservatory £8,000 to £35,000. Same-ish footprint, very different rooms. Here is the full comparison: cost, planning, warmth, lifespan, and value uplift.
Updated May 2026. FMB 2026 cost index, Checkatrade verified quotes from both garden room and conservatory installers, Federation of Garden Studio Builders pricing guidance.
Head-to-Head Price Comparison (2026)
| Size | uPVC Conservatory | Standard garden room | Premium garden room |
|---|---|---|---|
| 3m x 3m | £8,000 - £14,000 | £15,000 - £20,000 | £22,000 - £28,000 |
| 4m x 3m | £11,000 - £18,000 | £18,000 - £24,000 | £25,000 - £32,000 |
| 4m x 4m | £16,000 - £28,000 | £22,000 - £30,000 | £32,000 - £42,000 |
| 5m x 4m | £18,000 - £30,000 | £26,000 - £36,000 | £38,000 - £50,000 |
| 6m x 4m | £22,000 - £40,000 | £32,000 - £45,000 | £48,000 - £62,000 |
Conservatory: supply, build, base, glass roof. Garden room: supply, build, insulated walls and roof, electrics, basic decoration. Excludes site preparation if difficult access. Source: FMB 2026, Checkatrade garden room guide, Federation of Garden Studio Builders.
The Use-Case Question
The right choice between garden room and conservatory depends almost entirely on what the room is for. A conservatory is a glazed transitional space, designed to bring the garden into the house. It works best for breakfast rooms, secondary dining, casual seating, indoor gardening, and morning rooms. The defining feature is the glass: walls, roof, doors, all glazed. The defining limitation is thermal comfort: without a warm roof or extensive heating upgrades, conservatories are seasonal rooms.
A garden room is a separate insulated structure in the garden, used for purposes incidental to the main dwelling. The most common uses are home offices (the single biggest driver of UK garden room demand since 2020), gyms, art studios, music studios, yoga rooms, hobby spaces, and storage for sports equipment or garden tools. The defining feature is insulation and year-round usability. The defining limitation is the separation from the main house: you have to walk outside to use it, which makes it less suitable for daily living spaces like dining rooms.
The cleanest decision rule: if the room's purpose is daily living for the household (eating, lounging, family gathering), choose a conservatory or orangery attached to the house. If the room's purpose is a dedicated activity for one or two people that benefits from separation (work, exercise, creative practice), choose a garden room. Trying to use a garden room as a family dining room rarely succeeds because the trip outside in bad weather discourages daily use; trying to use a conservatory as a year-round home office often fails because of temperature swings without significant additional spec.
Planning Permission: Different Routes, Both Usually No
Both garden rooms and conservatories typically proceed under permitted development rights without full planning permission, but through different PD routes. A conservatory uses the rear extension PD provisions (Class A of Part 1 of the GPDO): single storey, up to 3 metres rear projection (4 for detached), up to 4 metres ridge height, up to 50% of garden coverage. A garden room uses the outbuilding PD provisions (Class E of Part 1): single storey, up to 2.5 metres maximum height within 2 metres of a boundary (or 4 metres ridge and 3 metres eaves otherwise), up to 50% of garden coverage, and used for purposes incidental to the dwelling.
The garden room PD is more flexible in some respects (no rear projection limit, no requirement to attach to the main house, no requirement for materials to match) but stricter in one important way: the use must be incidental to the dwelling. Overnight sleeping accommodation is not permitted under garden room PD; for guest bedrooms, holiday let units, or annexes used for family members on a permanent basis, full planning permission is required. The PD test of incidental use is enforced via the council's planning enforcement team where complaints arise; building an Airbnb in the garden without planning is a common source of enforcement action.
Both options have additional restrictions in conservation areas, AONBs, and listed buildings. The garden room PD is more often restricted in conservation areas than the conservatory PD because outbuildings can be more visually prominent in the wider streetscape than a rear extension. Always check the local authority's planning portal before committing to either option.
Build Time, Lifespan, Maintenance
Build time. A standard garden room typically takes 3 to 6 weeks from order to handover including a 2 to 4 week manufacturing lead time and a 1 to 2 week site install. A premium custom garden room takes 6 to 12 weeks. A standard uPVC conservatory takes 6 to 12 weeks from order to handover. A bespoke orangery takes 16 to 24 weeks. On pure speed, garden rooms typically win, particularly for the prefab modular options shipped on a flatbed lorry and craned into position in a day.
Lifespan. A quality uPVC conservatory has a 20 to 25 year expected lifespan before any major component replacement. Aluminium and hardwood conservatories last 30 to 50 years. A timber garden room with proper preservative treatment and routine maintenance lasts 25 to 40 years. The garden room's exposed timber needs treating every 5 to 8 years; conservatory uPVC needs only window cleaning. On long-term low-maintenance terms, the conservatory wins; on raw expected lifespan, both are comparable.
Maintenance. Conservatories need annual gutter clearance, occasional silicone reseal of glazing units (every 7 to 10 years), and decoration of any visible internal frames (none required for uPVC). Garden rooms need biannual exterior timber treatment, annual gutter clearance, occasional reroofing (EPDM flat roofs last 25 to 30 years), and decoration of timber cladding (every 5 to 8 years). Annual maintenance budget: conservatory typically £50 to £150, garden room typically £150 to £400.
Conservatory Cost Calculator
Enter your dimensions to estimate the conservatory cost side of the comparison. For garden room pricing, contact a Federation of Garden Studio Builders member for a quote.
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
Indicative estimate only. Obtain 3 written quotes.
Cost Breakdown
Excludes: flooring, heating, furniture, VAT where applicable, planning fees. VAT is typically 20% on labour and materials.
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Garden Room vs Conservatory FAQ
What is the difference between a garden room and a conservatory?
Which is cheaper: garden room or conservatory?
Does a garden room need planning permission?
Are garden rooms warmer than conservatories?
Which adds more value: garden room or conservatory?
Related Pages
Conservatory vs Extension
The other major comparison: conservatory versus full single-storey extension.
Conservatory vs Orangery
The closer cousin: orangery is the warm-roof high-spec version of a conservatory.
Warm Roof Conversion
The most cost-effective way to close the warmth gap if you have an existing conservatory.
4m x 3m Conservatory
The most-built UK conservatory size at the price point where the comparison usually starts.
Orangery
Highest-value option for resale ROI: bricks, lantern, year-round room.
Planning Permission
Full guide to PD routes and full planning for both conservatories and garden rooms.