Glass Room Extension Cost 2026:
Full UK Price Guide (Per m²)
How much could a glass room extension cost in 2026? Explore typical prices per m², what’s included (and what’s often not), and request an informal, no‑obligation quote.
David, our digital assistant, can take a few details – a specialist may then follow up without obligation.
Glass room extension costs: indicative 2026 ranges
Budget (conservatory style)
approx. £1,800 – £2,500 / m²
Mid‑range (orangery / hybrid)
approx. £2,500 – £3,800 / m²
Premium (glass box / frameless)
approx. £3,800 – £5,500+ / m²
Glass kitchen extension (typical 3x4m)
approx. £15,000 – £45,000
What is a glass room extension? (Also called a sunroom, orangery or glass box)
A glass room extension – sometimes referred to as a sunroom, garden room, or orangery – is a living space built with structural glazing. Unlike older conservatory designs, modern glass rooms often use high‑performance glass (low U‑value, solar control) and can incorporate solid roof sections or lanterns, aiming for improved comfort across more seasons.
Other names you might come across include “another name for a sunroom” – such as conservatory, glass box, orangerie. However, a true glass room extension is usually designed as an integral part of the home, rather than a simple bolt‑on.
Typical costs by glass room type (2026)
| Type | Typical size | Indicative 2026 range (installed) | Approx. per m² |
|---|---|---|---|
| Conservatory‑style glass room | 12–20 m² | £12k – £35k | £1,800 – £2,500 |
| Orangery / hybrid (brick pillars + glass) | 15–30 m² | £25k – £60k | £2,500 – £3,800 |
| Frameless glass box extension | 10–25 m² | £30k – £80k+ | £3,800 – £5,500+ |
| Glass kitchen extension (most popular) | 12–20 m² | £15k – £45k | £2,200 – £3,500 |
| Steel‑look / heritage glass structure | 15–30 m² | £28k – £70k | £2,800 – £4,200 |
*All figures exclude VAT (20% standard on residential extensions) and internal finishes. For a glass kitchen extension, you may also need to budget for kitchen fitting, flooring, and electrics – typically £5k–£15k extra.
What different cost levels can offer (per m²)
Budget (£1,800–2,500/m²) – Typically basic double glazing, standard frames, lean‑to roof. May work well for a three‑season sunroom.
Mid‑range (£2,500–3,800/m²) – Often thermally broken aluminium, U‑value around 1.0 W/m²K, solid roof or lantern. Designed for extended use throughout the year.
Premium (£3,800–5,500/m²) – Features like frameless corners, triple glazing (U‑value ≤0.6), solar control, integrated blinds. A high‑end living space.
What is typically included (and what may be extra)
| Item | Usually included? | Notes |
|---|---|---|
| Frames & glazing | ✅ Often yes | Structural glass and framing are typically part of the core quote. |
| Roof (glazed or solid) | ✅ Usually | Solid roof or lantern systems may be an added cost. |
| Foundations / groundworks | ⚠️ Rarely | Expect to budget separately – often £3k–£8k. |
| Underfloor heating | ❌ Typically no | Can add £2k–£5k depending on area. |
| Internal plastering / tiling | ❌ Usually no | Allow £1k–£3k. |
| Electrics & lighting | ❌ Generally no | £1.5k–£4k is a common range. |
| VAT (20%) | ❌ Almost always extra | Check if your supplier quotes inclusive or exclusive. |
| Planning permission fees | ⚠️ Varies | Some firms include, others charge separately – worth asking. |
Glass kitchen extensions: what we’re seeing in 2026
Based on recent projects we’ve been involved with, a 12m² (3x4m) glass kitchen extension might fall into these rough brackets:
- Budget approach (lean‑to, double glazing): around £18,000 – £25,000
- Mid‑range (orangery style, solid roof + lantern): roughly £28,000 – £38,000
- Premium specification (frameless corner, sliding doors): approximately £42,000 – £60,000
How to compare glass room quotes: a helpful checklist
1. U‑values – Look for ≤1.0 W/m²K if you want year‑round comfort.
2. Frame material & finish – Thermally broken aluminium or engineered timber?
3. Roof construction – Solid warm roof, self‑supporting lantern, or polycarbonate?
4. Glazing spec – Double vs triple, low‑E, solar control, argon fill.
5. Installation team – In‑house or subcontractors? (In‑house can mean better continuity.)
6. Warranties – Ask about guarantees on frames, glazing, and labour.
7. Planning & building regs – Who handles applications? Are fees included?
Glass room vs traditional extension: a comparison
| Factor | Glass room extension | Traditional brick extension |
|---|---|---|
| Cost per m² (mid‑spec) | £2,500 – £3,800 | £2,200 – £3,500 |
| Natural light | ⭐⭐⭐⭐⭐ (full height glass) | ⭐⭐⭐ (relies on windows) |
| Build time | 4–8 weeks | 8–12 weeks |
| Planning complexity | Often permitted development | Often requires full planning |
| Thermal efficiency potential | High (with triple glazing) | Very high (cavity insulation) |
| Added property value | 5–15% (varies by market) | 5–10% |
Our observation: If natural light and a strong connection to the garden are priorities, a glass room can be a great fit. For a fully opaque room (e.g., bedroom or home office), a traditional extension might be more suitable – though a hybrid glass room with a solid roof can offer a balance.
Thinking about a glass room extension? Let’s have a conversation.
Every project is different. We can help you explore options based on your home, preferred materials, and budget – with no obligation, just straightforward guidance from a team that has worked on many glass extensions over the years.
David, our digital assistant, can take a few details – a specialist may then follow up within 24h if that suits you.
More cost guides & inspiration
- Glass extension cost guide (detailed breakdown)
- Premium glass extensions price guide – luxury orangeries & frameless designs
- Frameless glass box extensions – gallery & technical notes
- Design portfolio: glass rooms & orangeries
📘 Note: For high‑end, premium glass extensions (orangeries, frameless modules), see our separate luxury price guide. This page focuses on typical glass room extension costs per m² across budget to premium levels.
Frequently asked questions
Honest answers to common queries about glass room costs
What is a glass room extension (also called a sunroom)?
A glass room extension – sometimes known as a sunroom, garden room, or orangery – is a living space built with structural glazing, often designed for improved year‑round comfort compared to older conservatories.
How much might a glass room extension cost per m²?
Indicative ranges: budget £1,800–£2,500/m², mid‑range £2,500–£3,800/m², premium £3,800–£5,500+/m². Final costs depend on many factors.
What are typical costs for a conservatory or orangery extension?
A conservatory might cost £12k–£35k; an orangery often £25k–£60k; a glass kitchen extension typically £15k–£45k. These are rough estimates.
Is a glass kitchen extension more expensive than a traditional one?
It can be – often 20–40% more than a brick‑and‑block build, due to engineered glass and thermal requirements. However, it can also add natural light and may enhance property appeal.
What is typically NOT included in a glass room quote?
Groundworks, underfloor heating, finishes, electrics, and VAT are commonly excluded. Always check your quote’s scope carefully.
How can I compare glass room quotes fairly?
Use our 7‑point checklist: U‑values, frame material, roof type, glazing spec, installer, warranties, and planning handling.
Call us for an informal chat – David can take a few details, and a glass room specialist may get back to you. 01243 538999 · Request a brochure
Request a personalised, no‑obligation quote
Tell us a little about your project – size, style, budget – and we’ll aim to provide a transparent, fixed‑price proposal within a few days.
Room Outside · Bespoke glass rooms since 1973 · Kent, Surrey, Sussex, Hampshire, London
