Glass roof: pros and cons
What it does well
- Keeps maximum daylight
- Solar control glass cuts glare and heat
- Self cleaning coatings
- Usually no building regs
What to weigh up
- Still colder than a solid roof in winter
- Can still overheat on south facing rooms
- Less insulation than tiled
Glass roof prices by conservatory style
Typical fitted prices, removal of the old roof and standard finishes. Tap a style for the full breakdown.
| Style | Small up to about 3m x 3m | Medium about 4m x 3.5m | Large about 5m x 4m or more |
|---|---|---|---|
| Victorian | £3,300 to £5,400 | £4,400 to £7,000 | £5,600 to £8,800 |
| Edwardian | £3,000 to £4,900 | £4,000 to £6,400 | £5,100 to £8,000 |
| Lean-to | £2,700 to £4,300 | £3,500 to £5,600 | £4,500 to £7,000 |
| Gable fronted | £3,000 to £4,900 | £4,000 to £6,400 | £5,100 to £8,000 |
| P-shape | £3,900 to £6,300 | £5,100 to £8,200 | £6,500 to £10,300 |
| T-shape | £3,900 to £6,300 | £5,100 to £8,200 | £6,500 to £10,300 |
A glass roof beats polycarbonate on almost everything except price: Which? rates it more thermally efficient, quieter in the rain and brighter. It does not beat a solid roof for winter warmth, and Which? warns that the more glass there is in a roof, the greater the chance of overheating. Which glass you choose makes most of the difference.
A conservatory does not have to keep a glass roof, but staying glazed has one practical advantage. Replacing a glazed roof with another glazed roof normally keeps the conservatory within the building regulations exemption, provided it still meets the conditions afterwards, while a solid roof needs an application.
Are glass conservatory roofs double glazed?
Modern ones are. Ultraframe says all of its roof glass is self cleaning, toughened and double glazed as standard, typically 24mm sealed units with argon gas between the panes. What has changed since the 1990s is the coatings. Ultraframe’s own figures show the gap:
| Roof glazing | U-value (heat lost, lower is warmer) | Sun’s heat let in |
|---|---|---|
| Standard double glazed unit | 2.8 | 75% |
| Performance glass, standard range | 1.2 | 24% to 70%, by tint |
| Performance glass, 4S and Ultimate range | 1.0 | 18% to 45% |
| 25mm clear polycarbonate | 1.7 | 63% |
So a roof with plain double glazing loses nearly three times as much heat as a good modern unit. For comparison, makers of solid tiled roofs claim around 0.15, so even the best glass loses several times more heat than an insulated roof.
How a new glass roof is built
A glass roof is a kit of aluminium glazing bars with PVCu or aluminium cappings, a ridge, an eaves beam along the tops of the frames and, where the design calls for them, tie bars. Ultraframe says each of its roofs is engineered for the local wind and snow loads by postcode. Pitches vary by system: Ultraframe’s glass roof runs from 15 to 40 degrees at the ridge, with a low-pitch eaves beam that allows 2.5 degrees on lean-tos.
If you have polycarbonate now, expect a whole new roof rather than glass dropped into the old bars. Glass units are heavier and thicker, so installers such as Vivaldi say the job usually needs a roof designed for glass, and LABC notes that frames built for polycarbonate may only be reinforced for that load. One MoneySavingExpert thread contrasts a £1,700 quote to glaze the existing bars with £6,000 for a complete new roof, so check that your quotes describe the same job.
Which glass: blue, bronze, neutral or clear?
The tint trades light against heat. The more reflective the coating, the less of the sun’s heat gets in, and the less daylight too. Published figures for some common roof glasses:
| Glass (maker) | Light let through | Sun’s heat blocked | U-value |
|---|---|---|---|
| Activ Clear (Pilkington) | 62% | No solar control | 1.0 |
| Activ Blue (Pilkington) | 42% | 67% | 1.0 |
| Activ SunShade Blue (Pilkington) | 18% | 83% | 1.0 |
| Conservaglass Blue 4S (Ultraframe) | 48% | 67% | 1.0 |
| Conservaglass Ultimate Blue (Ultraframe) | 24% | 82% | 1.0 |
| BIOCLEAN+ Azura+ (Saint-Gobain) | 23% | 83% | 1.0 |
Ultraframe advises high light transmission and lower solar rejection for north or east facing rooms, and low light transmission with high solar rejection for south or west facing ones. The Glass and Glazing Federation makes the same split: low-emissivity coatings for north-facing conservatories, solar control for south-facing. Bear in mind that at 18% to 24% light transmission the room is noticeably dimmer, and so is any room behind it. Our guide to solar control and self-cleaning glass compares more products.
Does self-cleaning glass work on a conservatory roof?
It works with the weather rather than instead of you. The coating breaks down organic dirt in daylight and makes rain sheet off, so it needs both rain and slope. Pilkington recommends a roof angle of at least 10 degrees, and Which? gives the same figure. It works less well on shallow lean-tos, in sheltered corners and anywhere silicone sealant has run onto the glass, which is why Ultraframe’s guidance is to seal self-cleaning glass with MS polymer sealant, not ordinary silicone.
It is worth having: 10% of Which? members surveyed in April 2026 regretted how hard their conservatory glass was to keep clean.
Glass roof systems you will be offered
These are the systems UK installers commonly fit. The claims are the makers’ own.
- Ultraframe Glass Roof (formerly Classic): BBA approved, which Ultraframe says makes it the only glass conservatory roof system with that approval. 10-year parts guarantee.
- Ultraframe Quantal: aluminium outside, uPVC inside, with thermal breaks. Ultraframe says U-values of 1.1 to 1.5 are achievable with high specification units. Pitches down to 2.5 degrees.
- Wendland (part of the same group as Ultraframe): pitches from 5 to 41 degrees and lean-to projections up to 5.9m.
- Prefix Glass Roof: BBA approved, 10-year parts guarantee. Prefix is now a trading division of Ultraframe.
- Liniar: sold through fabricators, with 10-year guarantees on the profiles and on glass unit seals.
- Eurocell: BBA accreditation giving a life expectancy of at least 25 years at pitches from 2.5 to 45 degrees.
- Conservatory Outlet: sold through its Premium Retailers with a 20-year roof guarantee and an insurance-backed guarantee.
If your current roof is a Synseal Global or K2, the original makers have gone. Synseal entered administration in 2019, Global spare parts are getting harder to find, and a repair company says K2 roof parts have run out entirely. That can make a replacement more practical than a repair.
Who a glass roof suits, and who it does not
Glass suits you if daylight and the sky view matter most, if the room faces north or east, or if the room behind borrows its light from the conservatory. It also avoids the building regulations application that a solid roof needs, as long as the conservatory still meets the exemption. See how it stacks up in glass vs polycarbonate.
It suits less well if you want a room at house temperature all winter, where a tiled roof or a hybrid roof will do far better. The same goes for a south or west facing room that already cooks in summer: strong solar control glass helps, but it will not match a solid roof. Our page on a conservatory that is too hot covers the cheaper fixes too.
Questions to ask before you sign
When you get quotes, ask each installer:
- Which glass exactly, and what are its light transmission, solar rejection and U-value figures?
- Is this a new roof designed for glass, or glass in my existing bars?
- Have my frames been checked for reinforcement, and are tie bars needed?
- Are roof vents included? Which? says roof vents let hot air escape upwards.
- How long is the guarantee on the sealed units, and separately on the roof and the workmanship?
- Is scaffolding in the price?
The glass roof cost guide shows typical prices by size and shape.
Systems installers will offer you
Named products sold through UK installers. Specs are from each maker's published data.
Ultraframe Glass Roof (formerly Ultraframe Classic)
Tested watertight in winds up to 130mph
- Made byUltraframe (UK) Ltd
- U-value1.0 W/m²K (maker's figure)
- Guarantee10 years
- CertificationBBA approval (Ultraframe claims it is the only glass conservatory roof system to hold BBA approval; Wikipedia says it was the first roofing system to obtain BBA approval, in 1996)
Quantal aluminium roof
Can be adjusted to 2.5 degrees pitch
- Made byUltraframe (UK) Ltd
- U-value1.1 W/m²K (maker's figure)
- Guarantee10 years
- CertificationBBA accredited (consumer page)
Prefix Systems Glass Roof
Developed over 30 years (Prefix search snippet)
- Made byPrefix Systems
- Guarantee10 years
- CertificationFully BBA approved (Prefix page)
Wendland Glass Roof
Pitches from 5 to 41 degrees (website); technical guide gives MK5 ridge 15 to 40 degrees and a lean-to option at 2.5 to 30 degrees
- Made byWendland
Liniar conservatory roof
Liniar states it is the only roof system offered with glass as standard (search snippet)
- Made byLiniar
- Guarantee10 years
Conservatory Outlet replacement glass roof
Insurance backed guarantee via retailer
- Made byConservatory Outlet
- Guarantee20 years
- Typical price£5,000 to £12,000
How it compares with the other options
| Option | Typical price | Summer comfort | Winter warmth | Quiet in rain | Daylight | Value for money | Fitting | Building regs |
|---|---|---|---|---|---|---|---|---|
| Tiled roof | £7,400 to £12,100 | 3 to 6 days | Building regulations approval needed | |||||
| Glass roof | £3,500 to £7,000 | 2 to 4 days | Usually exempt when like for like | |||||
| New polycarbonate roof | £2,700 to £5,200 | 1 to 2 days | Exempt when like for like | |||||
| Hybrid roof | £6,600 to £12,600 | 4 to 7 days | Building regulations approval needed | |||||
| Insulated roof panels | £1,800 to £4,600 | 1 to 3 days | Depends on the system, check before you buy | |||||
| Orangery conversion | £14,000 to £35,000 | 7 to 15 days | Building regulations approval needed |
Questions about glass roofs
Is blue glass good for a conservatory roof?
Blue tints are among the more common solar control options, and they suit rooms facing south or west. Pilkington's Activ Blue lets through 42% of the light and blocks 67% of the sun's heat, while the strongest blue options block 82% to 83% of the heat but let through only 18% to 24% of the light. For a north or east facing room, a clearer glass keeps more daylight.
Can I put glass into my existing polycarbonate roof frame?
Usually not. Glass sealed units are heavier and a different thickness from polycarbonate, so installers generally fit a complete roof designed for glass. LABC also notes that frames built for a polycarbonate roof may only be reinforced for that load, so they need checking before glass goes on.
What happens if a glass roof panel mists up inside?
Misting between the panes means the sealed unit has failed, and it cannot be repaired, only replaced. ExpertSure puts a replacement at £300 to £600 per panel including labour and scaffolding. Roof glass units usually carry a 10-year warranty, so check the date on yours first.
Can you stand on a glass conservatory roof?
No. Ultraframe says it is not safe to stand directly on a conservatory roof of any kind, and suggests hiring special ladders for maintenance access. Self-cleaning glass reduces how often you need to reach it.
How much does a glass roof cost for a conservatory?
A typical glass roof for a medium conservatory (about 4m x 3.5m) costs £3,500 to £7,000 fitted. A small conservatory starts around £2,700 and a large one can reach £8,800. A medium lean-to is usually £3,500 to £5,600, and a medium Victorian £4,400 to £7,000.
How long does it take to fit a glass roof?
Most installs take 2 to 4 days from stripping the old roof to handing over. Bigger or more complex shapes, and any work on the frames or base, add time.
Do I need building regulations for a glass roof?
Usually exempt when like for like. Replacing one translucent roof with another usually keeps the conservatory within the exemption, provided it stays separated from the house by external quality doors and has no extension of the main heating. Building regulations guide.
How long does a glass roof last?
Expect 25 years plus, depending on the system, the installer and the maintenance. Check the length and type of guarantee on each quote, and whether it is insurance backed.
Sources
- Which?: conservatory common pitfalls
- Which?: how to keep a conservatory cool
- Ultraframe: Glass Roof Technical Guide (May 2025)
- Ultraframe: glass roofs
- Pilkington: Activ self-cleaning range
- Saint-Gobain Glass: SGG BIOCLEAN
- Glass and Glazing Federation: conservatories and energy efficiency
- Vivaldi: replacing a polycarbonate roof with glass
- LABC: guidance on solid roofs to conservatories
- Building Regulations 2010, regulation 9
- ExpertSure: conservatory roof replacement cost
