Orangery vs Extension London: Which Is Right for You?
Orangeries cost £30k-£80k (£500-£1,000/m² cheaper than extensions) and flood spaces with natural light. Extensions cost £50k-£120k but offer better thermal mass and durability. Complete comparison guide.
Quick Comparison
Orangery (20m²)
- Cost: £40k-£60k (£2,000-£3,000/m²)
- 60-70% glazing (roof + walls)
- Often qualifies as PD (no planning needed)
- Timeline: 8-12 weeks build
Brick Extension (20m²)
- Cost: £60k-£80k (£3,000-£4,000/m²)
- 30-40% glazing (doors/windows only)
- May qualify as PD depending on size
- Timeline: 12-16 weeks build
What's the Difference? Defining Orangeries vs Extensions
Orangery Definition
An orangery is a predominantly glazed structure with brick or masonry piers (typically 30-50% solid walls) and a glazed roof with a perimeter flat roof or lantern. According to Homebuilding & Renovating, modern orangeries sit between conservatories (100% glass) and extensions (mostly solid walls).
- •Roof: Glass lantern or flat roof with roof lights (60-80% glazed)
- •Walls: Mix of brick piers and full-height glazing (50-70% glass)
- •Structure: Lightweight foundations, prefabricated frames
- •Feel: Light-filled, garden room aesthetic, transitional space
Traditional Extension Definition
A brick extension is a fully enclosed addition with solid roof, cavity wall construction, and windows/doors only for glazing. Treated as permanent living space identical to main house.
- •Roof: Flat roof with insulation or pitched tile/slate roof (fully solid)
- •Walls: Full cavity wall construction, insulation, matching brickwork (70-90% solid)
- •Structure: Deep foundations, structural walls, heavy construction
- •Feel: Seamless integration with existing house, permanent room
Key distinction: Orangeries are about maximizing light while maintaining some thermal separation from the garden. Extensions are about maximizing permanence and thermal performance while adding functional living space. Orangeries feel like "garden rooms," extensions feel like "extra house."
Cost Comparison: Orangery vs Extension London 2025
According to Checkatrade, orangeries typically cost £500-£1,000/m² less than equivalent brick extensions in London due to less groundwork, lighter structure, and faster installation.
| Size | Orangery Cost | Extension Cost | Saving |
|---|---|---|---|
| Small (12-15m²) | £30,000-£45,000 | £42,000-£60,000 | £12k-£15k |
| Medium (16-20m²) | £40,000-£60,000 | £60,000-£80,000 | £20k |
| Large (25-30m²) | £60,000-£90,000 | £90,000-£120,000 | £30k |
Why Orangeries Cost Less
Lighter Foundations
Orangeries use pad foundations rather than deep strip foundations. Less excavation, less concrete, faster installation. Brick extensions require foundations 1m+ deep, orangeries need 600-800mm.
Prefabricated Components
Aluminium frames, glazed panels, and roof lanterns arrive pre-made. Extensions require on-site bricklaying, carpentry, roofing trades. Orangery: 2-3 trades. Extension: 6-8 trades.
Faster Build Time
8-12 weeks for orangery vs 12-16 weeks for extension. Less labour cost, less scaffolding hire, less site setup cost. Every week saved = £500-£800 in reduced overhead.
Less Roofing Work
Glass lantern roof (£3k-£6k) vs flat roof with insulation, waterproofing, drainage (£7k-£14k) or pitched tile roof (£10k-£18k). Orangery roofs arrive as complete units, crane-lifted into place.
Total savings: £14k-£28k on typical 20m² project. However, high-end orangeries with bespoke glazing, Crittall-style frames, and premium lanterns can cost £3,500-£4,000/m² - matching or exceeding extension costs. The savings apply to mid-range projects.
Thermal Performance: The Critical Difference
This is where orangeries and extensions differ most significantly. According to SupaLite, modern orangeries with high-performance glazing (U-values below 1.0) can match brick extension thermal performance, but practical real-world experience tells a different story.
Orangery Thermal Reality
Summer Performance: ★★☆☆☆
Even with solar control glass, glazed roofs overheat in summer (28-32°C typical). Requires blinds, ventilation, often unusable 11am-4pm on hot days. Air conditioning necessary for year-round comfort (£2k-£4k extra).
Winter Performance: ★★★☆☆
Modern triple-glazed units perform reasonably (18-20°C with heating). However, glass has lower thermal mass than brick - heats quickly, cools quickly. Underfloor heating essential (£80-£120/m²).
Annual Heating Cost: ★★☆☆☆
20m² orangery: £400-£600/year heating cost vs £250-£350/year for equivalent extension. 40-70% higher energy bills despite modern glazing.
Extension Thermal Reality
Summer Performance: ★★★★☆
Solid insulated roof stays cool (22-25°C typical). Thermal mass of brick walls moderates temperature. Usable all day with windows open for ventilation. No air conditioning needed unless very large glazed doors.
Winter Performance: ★★★★★
Cavity walls with 100mm insulation + solid roof = excellent heat retention (19-21°C typical). Thermal mass means room stays warm for hours after heating off. Radiators sufficient, underfloor heating optional.
Annual Heating Cost: ★★★★★
20m² extension: £250-£350/year heating cost. Performs like any other room in house. No temperature regulation issues, predictable running costs.
Honest assessment: Orangeries with 60-70% glazing will never match the thermal comfort of brick extensions, despite marketing claims about "high-performance glazing." Physics is physics: glass conducts 5-10x more heat than insulated walls.
If you value year-round comfortable temperature and lower energy bills, choose extension. If you value natural light and accept seasonal temperature fluctuations, choose orangery.
Planning Permission: Orangery vs Extension
According to 4D Planning, both orangeries and extensions can qualify under Permitted Development rights if they meet the same criteria. The glazed vs solid distinction doesn't affect PD eligibility - size and location rules apply equally to both.
Permitted Development Criteria (Apply to Both)
- Single-storey rear extension only (not side, not front)
- Maximum 3m projection (terraced/semi) or 4m (detached)
- Maximum 4m height, or 3m within 2m of boundary
- Covers less than 50% of garden/land
- Eaves/ridge not higher than existing house roof
- Not in conservation area, AONB, listed building, or Article 4 area
When Planning Permission IS Required
For Both Orangeries and Extensions:
- •Exceeds PD size limits (3m/4m rear projection)
- •Side extension (orangeries along side return need planning)
- •Two-storey structure
- •Conservation area, listed building, or Article 4 restrictions
- •Flat or maisonette (PD doesn't apply)
Myth-busting: Many websites claim "orangeries don't need planning permission." This is misleading. Orangeries and extensions follow identical PD rules. Both need planning if they exceed size limits. The 60%+ glazing of an orangery doesn't grant automatic PD exemption. Always check with your local planning authority or apply for Lawful Development Certificate.
Decision Framework: Orangery or Extension?
Choose Orangery If:
- Natural light is top priority - you want bright, airy space that feels connected to garden
- Budget is £30k-£70k - £15k-£25k less than equivalent extension
- Timeline matters - orangery built in 8-12 weeks vs 12-16 weeks for extension
- Use is seasonal/occasional - summer dining room, home office in spring/autumn, not critical living space
- You're okay with temperature fluctuations - accept it'll be hot in summer, need extra heating in winter
- Garden room aesthetic appeals - you want transitional indoor-outdoor space, not seamless house integration
Choose Extension If:
- Year-round comfortable temperature is essential - you need proper living space usable daily
- Energy efficiency matters - lower running costs, better for environment
- Maximum ROI needed - extensions add 12-15% value, orangeries add 8-10%
- Use is essential daily space - main kitchen-diner, bedroom, critical family room
- Longevity matters - extensions last 80-100+ years with minimal maintenance, orangeries 30-40 years before glazing/frame replacement
- Budget allows £60k+ - can afford proper extension with good finishes
Frequently Asked Questions
Do orangeries add more value than extensions?
No. Extensions typically add 12-15% property value, orangeries add 8-10%. On £700k London property: extension adds £84k-£105k value (90-115% ROI on £80k cost), orangery adds £56k-£70k value (85-110% ROI on £55k cost). Extensions win on ROI because buyers value permanent living space over seasonal garden rooms. However, orangeries cost less upfront, so net gain can be similar.
Can I add an orangery myself or do I need specialists?
DIY foundations and brickwork is possible if experienced, but glazing installation requires specialists (aluminium frames, roof lantern lifting, waterproofing details). Most homeowners hire orangery companies who supply complete kits with installation (£35k-£75k turnkey). Self-build with sub-contractors: £25k-£55k but requires project management skills. Extensions need full construction team - not practical for DIY unless you're a builder.
Will my orangery be too hot in summer and cold in winter?
Honest answer: yes, if you choose 60-70% glazing. Even with solar control glass and triple glazing, expect 28-32°C summer afternoons (unusable without air con) and higher heating costs in winter (40-60% more than equivalent extension). Solution: specify less glazing (40-50% max), solid insulated roof with just roof lights, or accept seasonal use. Don't believe marketing about "thermal performance equal to extensions" - it isn't.
Can I convert an orangery to a full extension later?
Technically yes, but expensive. You'd need to: replace roof lantern with solid insulated roof (£8k-£15k), replace some glazed walls with cavity brick walls (£5k-£10k), upgrade foundations if orangery used lightweight pads (£4k-£8k). Total: £17k-£33k. More cost-effective to build extension correctly from start. However, some do "orangery now, upgrade later" if budget is tight initially.
What's the maintenance difference between orangery and extension?
Orangeries: Clean roof glazing 2x/year (£150-£300 each time), replace seals/gaskets every 10-15 years (£1k-£2k), repaint/refinish aluminium frames every 15-20 years (£2k-£4k). Extensions: Roof inspection every 5 years (£200), repaint render every 20 years (£2k-£3k), repoint brickwork every 40-60 years (£3k-£5k). Extensions have lower ongoing maintenance costs.
Should I compromise with a "hybrid" - extension with large glazing?
Yes, often the best solution. Solid insulated roof + cavity walls + 40-50% glazing (full-width bi-fold doors, side windows, 2-3 roof lights). Cost: £2,800-£3,400/m² (between orangery and full extension). Gives you: excellent thermal performance of extension, significant natural light from strategic glazing, year-round comfort. This is what most architects recommend for kitchen-diners - better than pure orangery or minimal-glazing extension.
Summary
Orangeries cost £30k-£80k (£2,000-£3,000/m²) vs extensions at £60k-£120k (£3,000-£4,000/m²). Orangeries deliver exceptional natural light and cost £500-£1,000/m² less but have higher energy bills (40-60% more heating cost), seasonal temperature issues, and lower ROI (8-10% vs 12-15% for extensions).
Choose orangery if: Budget is £30k-£70k, natural light is priority, seasonal use is acceptable, garden room aesthetic appeals. Choose extension if: Year-round comfort essential, energy efficiency matters, maximum ROI needed, permanent living space required.
Best compromise: Hybrid design with solid insulated roof + cavity walls + 40-50% strategic glazing. Delivers 80% of orangery's light with 90% of extension's thermal performance. Cost: £2,800-£3,400/m².