Extension vs Conservatory Cost UK
Estimates based on UK trade benchmark data, updated 25 April 2026. Methodology →
Extensions and conservatories can both add space, but they deliver very different comfort levels and long-term value. This guide compares extension vs conservatory costs in the UK in 2026, including realistic budget bands, usability trade-offs, and where each option makes the most sense.
Most projects fall between £28,560 and £38,640. Budget refreshes start near £9,120; premium projects reach up to £81,900.
All prices are approximate UK averages including labour and materials unless stated otherwise.
Typical UK Cost by Scenario
Typical timeline: 2 to 14 weeksBudget
£18,000
typical figure
- Focused essentials
- Practical finishes
Mid-range
Most common£33,600
typical figure
- Balanced specification with core upgrades
- Reliable materials
Premium
£61,110
typical figure
- Premium materials
- Wider scope with higher coordination demands
Figures are typical UK averages including labour, materials, and VAT at 20% for standard-rated work.
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Typical UK Cost Ranges for Extension vs Conservatory
| Item | Cost Range |
|---|---|
| Conservatory (lean-to, small) | £9,600 – £18,000 |
| Conservatory (medium) | £14,400 – £26,400 |
| Orangery / solid roof conservatory | £24,000 – £54,000 |
| Single-storey extension (15 m²) | £26,400 – £54,000 |
| Single-storey extension (25 m²) | £42,000 – £78,000 |
| Year-round comfort | £0 – £0 |
All prices are approximate UK averages including labour, materials, and VAT at 20% (2026). Some qualifying renovations for empty homes may use the reduced 5% VAT rate.
Real UK Cost Examples
- Budget scenario (3-bed terrace, Cardiff): focused essentials and practical finishes. Not done: major layout or structural changes. Approx cost: £7,600 to £22,400.
- Mid-range scenario (typical homeowner, 4-bed detached): balanced specification with core upgrades and reliable materials. Approx cost: £23,800 to £32,200.
- High-end scenario (bungalow): premium materials and wider scope with higher coordination demands. Main cost drivers: specification level and complexity. Approx cost: £33,600 to £68,250.
Related next steps:
What You Can Get For Your Budget
- Around £19,600: core refresh and essential upgrades, usually with no major layout change.
- Around £28,000: balanced refit scope with better materials and targeted performance improvements.
- £42,000+: wider flexibility on finish quality, scope depth, and more complex works.
Hidden Costs to Watch For
- Groundworks and thermal-spec upgrades can push costs beyond entry-level assumptions.
- Waste removal, making-good, and repeat trade visits are common late-budget increases.
- Compliance and certification items are often missing from initial summary quotes.
- In most UK projects, scope changes after works start are where costs escalate fastest.
Related next steps:
Should You Do This Renovation?
- Usually worth it when extension vs conservatory solves a clear usability, compliance, or energy-performance problem.
- Less worth it when the main issue is cosmetic and resale timing is short-term.
- ROI is strongest when scope is disciplined and specification matches local value levels.
Common Cost Mistakes
- Underestimating labour and preliminaries while focusing only on material prices.
- Changing scope mid-project without budget re-baselining.
- Choosing the cheapest quote without checking detailed inclusions and exclusions.
- Running too little contingency for hidden defects and compliance upgrades.
Key Cost Factors
- Conservatory — cheaper per m²; often permitted development; can be cold in winter and hot in summer unless upgraded; uPVC or aluminium frame.
- Extension — full insulation, heating, and building regs; usable year-round; higher cost; may need planning for larger sizes.
- Orangery / solid roof — bridges the gap; more comfortable than all-glass conservatory but usually cheaper than full extension.
- Planning — conservatories often permitted dev; extensions beyond certain size need planning.
- Use — if you want a proper room (e.g. kitchen-diner), extension is the right choice; if you want a sunroom or occasional space, conservatory can suffice.
- Location — both cost 15–25% more in London and the South East.
Cost Checkpoints
Use these checkpoints to sequence spend decisions, protect your core scope, and reduce late-stage budget overruns.
- Prioritise single-storey extension (25 m²) first: typical range £42k to £78k can shift the whole project budget if scope changes late.
- Prioritise orangery / solid roof conservatory next: typical range £24k to £54k can shift the whole project budget if scope changes late.
- Use £28k as a working midpoint and hold a contingency of roughly 10% to 15% for unknowns and making-good works.
- Request like-for-like quotes with labour, materials, and exclusions split out so you can compare options without hidden scope gaps.
Typical Timeline
| Item | Duration |
|---|---|
| Conservatory (small) | 2 to 3 weeks |
| Conservatory (medium) or orangery | 3 to 6 weeks |
| Single-storey extension | 8 to 14 weeks |
Regional Cost Variations
Extensions and conservatories in London and the South East cost 15–25% more than national averages.
Costs in your area
Compare regional benchmarks for extension vs conservatory using the same UK baseline assumptions.
Ways to Reduce Costs
- If budget is tight and you accept seasonal use, a conservatory is the cheaper option.
- For a kitchen or daily living space, an extension is worth the extra cost for comfort.
- Orangery or solid-roof conservatory improves comfort over all-glass; compare cost to a small extension.
- Check permitted development limits for both; conservatories have size and height rules.
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Extension vs Conservatory: Decision Guide
| Item | Cost Range |
|---|---|
| Typical cost range | £55k-£140k – £8k-£35k |
| Best for | Year-round integrated living space – Lower-cost additional daylight room |
| Thermal performance | Higher with compliant insulation standards – Varies significantly by glazing specification |
| Longevity/value | Usually stronger resale impact – Lower capital risk but lower perceived value uplift |
Extension Pros
- Creates permanent, fully integrated floor area.
- Better year-round comfort and energy performance when designed well.
- Often stronger long-term value for family homes.
Extension Cons
- Higher cost and longer programme.
- More planning/building-control complexity.
- Greater disruption to existing living areas.
Conservatory Pros
- Lower upfront budget and faster installation.
- Good option for light-filled informal space.
- Can be attractive when major structural work is not viable.
Conservatory Cons
- Comfort can drop in winter/summer without premium spec.
- Generally lower resale impact than a true extension.
- Layout integration is often weaker than masonry builds.
When each option works best
- Retired couple selects high-spec conservatory for bright garden room at lower cost than a full extension.
- Young family chooses extension to create insulated kitchen-dining hub used all year and better aligned with resale goals.
When to Choose Each Option
- Choose extension when thermal comfort, integrated layout, and long-term value are your priorities.
- Choose conservatory when budget speed and natural light are the main drivers, and occasional-season use is acceptable.
- For borderline cases, compare lifecycle costs including heating/cooling rather than headline install price alone.