Conservatory vs Extension vs Garden Room: UK Cost and Decision Guide (2026)
Three ways to add space to your home. Here is what each costs, how long each takes, and which is the right choice for your situation.
Updated April 2026. Independent guide.
Four-Way Comparison
| Feature | Conservatory | Extension | Garden Room | Orangery |
|---|---|---|---|---|
| Typical cost | £8k - £35k | £30k - £80k+ | £15k - £40k | £25k - £80k+ |
| Build time (on site) | 1-2 weeks | 8-20 weeks | 2-6 weeks | 3-6 weeks |
| Total project time | 6-14 weeks | 20-40 weeks | 6-12 weeks | 12-24 weeks |
| Planning permission | Usually not needed | Often required | Usually not needed | Usually not needed |
| Building regs | Usually exempt | Always required | Sometimes exempt | Always required |
| Winter warmth | Needs investment | Fully insulated | Good with insulation | Good naturally |
| Year-round use | With warm roof and heating | Yes | Yes | Yes |
| Value added | 5-10% | 10-20% | Neutral to slight positive | 8-15% |
| Disruption to home | Low | High (months) | Low to moderate | Moderate |
| Plumbing possible? | Complicated (triggers BR) | Yes | Complicated | Complicated |
Decision Guide: Which Is Right for You?
Choose a conservatory when...
- +Budget is under £25,000
- +You want the project done in under 3 months
- +You primarily want a garden-facing room for spring/summer
- +You are happy to add a warm roof later if needed
- +You want to preserve as much garden as possible (lean-to options)
- +The house suits a glass extension aesthetically
Choose a full extension when...
- +You need a kitchen-diner or utility room extension
- +You need plumbing or gas connections
- +You plan to sell within 5-10 years and want maximum value uplift
- +Budget is above £40,000 and you want a permanent room
- +You want to extend upstairs at the same time
- +The roof of the extension will be below the existing eaves (no planning issue)
Choose a garden room when...
- +You need a home office away from the main house noise
- +You want the structure to be detached (separate council tax assessment applies)
- +Budget is £15,000-£30,000 for a good quality, insulated space
- +You want a gym, hobby room, or creative studio
- +Planning restrictions make a house extension difficult
- +You want a structure that can be removed or sold on
Does a Conservatory Add Value Compared to an Extension?
An extension consistently delivers stronger property value uplift than a conservatory, primarily because it adds habitable floor space that counts toward the house's official square footage. An extension's 10-20% uplift reflects this. A conservatory's 5-10% is lower because it is not universally counted as habitable space by surveyors.
However, the comparison on cost-per-pound-of-value-added is more nuanced. A £15,000 conservatory that adds 5% to a £300,000 house adds £15,000 in value - breaking even. A £50,000 extension that adds 15% to the same house adds £45,000 - a net cost of £5,000. On this basis, the conservatory is the better value for money investment, even though the extension adds more total value.
The caveat: quality matters more than type. A poorly built conservatory that is cold, leaking, or built without required planning or building regulations approval will actively harm the sale of the property. A superbly built, year-round-usable conservatory with proper documentation will hold its value better than a mediocre extension.