Yes, a glass conservatory roof can be replaced with insulated panels without changing the frame. Double glazed roof units fitted before 2002 have a U-value of about 2.8, and our 75 mm panels are about 0.43, so heat loss through the roof falls by roughly 85 percent. Fitted prices start from £3,000, usually less than the £350 to £550 per m² of new glass.
Why glass roofs disappoint
Glass roofs were sold as the premium choice, and on a mild spring day they are lovely. The rest of the year tells a different story, because a glass roof is a large window laid flat towards the sky. The problems below are the ones we hear about most.
- Summer heat and glare: the sun comes straight through the roof, and a conservatory under glass can pass 35 to 40°C. Solar control coatings help a little, but the room is still hard to use by mid afternoon.
- Winter cold: older double glazed roof units lose heat fast, and even modern low-e glass loses more than twice as much as our panels.
- Misted units: when the seal of a sealed unit fails, moisture gets between the panes and the unit mists up for good.
- Condensation on the bars: the glass and bars are cold on the inside face, so water forms there and runs down.
- Cleaning: leaves, moss and bird mess all show from below, and you cannot safely walk on the roof to clean it.
New glass or insulated panels?
If your glass roof is failing, you can replace it with new glass. A replacement glass roof costs about £350 to £550 per m², which is £3,300 to £5,200 for a 3 m by 3 m roof. It will be better than what you have, but it will still let the summer sun in.
| Roof | U-value (W/m²K) | Heat lost through a 12 m² roof at 20°C difference | Direct summer sun |
|---|---|---|---|
| Glass fitted before 2002 | about 2.8 | 672 W | Comes straight in |
| Modern low-e roof glass | 1.0 to 1.2 | 240 W to 288 W | Reduced, still comes in |
| Our 75 mm insulated panels | about 0.43 | 103 W | Blocked, except through roof lights |
Over a heating season in England, a 12 m² pre-2002 glass roof loses around 1,734 kWh, against about 266 kWh through our panels. If you kept the room warm all winter, the difference is worth roughly £386 a year on electricity at 26.32p per kWh, or about £117 on gas at 7.97p. The conservatory roof U-values guide shows how these sums work.
Weight
Glass is heavy. A double glazed roof unit made of two 4 mm panes weighs about 20 kg per m² before the frame is counted. Our panels weigh less than the sealed units they replace, so on a glass roof conversion the load on your frame goes down rather than up.
Keep some daylight with roof lights
Going from a clear roof to a solid one is the biggest change you will notice, so plan the light at the survey. Most people add one or two glazed roof lights at £395 each, placed over the part of the room where they sit or eat. The inner face of every panel is white, which reflects the light that comes in through the side windows.
If you are worried about the room feeling closed in, read our guide on whether a solid roof makes a conservatory dark. The walls stay mostly glass, so the room still gets side light all day.
How we take out a glass roof
- We protect your floor and furniture and close off the room.
- Caps and gaskets come off, then each glass unit is lifted out by two fitters and stacked safely outside.
- We check the glazing bars, ridge and gutter beam, and point out any damage before going on.
- Your made-to-measure panels go onto the bars under new caps and seals, followed by the ridge, hip and wall trims.
- The old glass is taken away and recycled.
Glass units are heavy and awkward to handle, so taking them out takes a little longer than lifting off polycarbonate. We keep the room closed off until every unit is down and out of the way, and we check for any broken glass before the panels go on.
A small roof is usually done in 1 day, a medium roof in 1 to 2 days, and a large roof or P-shape in 2 to 3 days. Most single storey roofs need no scaffold.
What it costs
A fitted panel roof works out at about £250 to £450 per m² of roof, below the usual price of new glass. The table shows guide prices by style and size.
| Style | Small (0 to 12 m²) | Medium (12 to 25 m²) | Large (25 m² and over) |
|---|---|---|---|
| Lean-to | £3,000 to £3,550 | £3,950 to £4,700 | £5,450 to £6,450 |
| Edwardian | £3,200 to £3,800 | £4,200 to £4,950 | £5,800 to £6,850 |
| Victorian | £3,300 to £3,900 | £4,350 to £5,150 | £6,000 to £7,100 |
| Gable end | £3,350 to £4,000 | £4,450 to £5,250 | £6,100 to £7,250 |
| P-Shape | £3,500 to £4,150 | £4,600 to £5,450 | £6,300 to £7,500 |
Every price includes removing the glass, the panels in your colour, fitting, the building control application and a 10 year insurance backed guarantee. Extras are roof lights (£395 each), LED spotlights (£345) and new gutters and fascia (£295). The conservatory roof cost calculator gives a figure for your own shape and size.
Building control and planning
A conservatory is exempt from building regulations only while at least 75% of the roof and 50% of the walls are translucent, the floor area is under 30 m², it is separated from the house by external quality doors, and it has no fixed heating from the house system. Replacing a glass roof with an insulated one ends that exemption, so building control approval is normally needed.
The target U-value for a new roof element under Approved Document L (2021 edition) is 0.15 W/m²K, and officers vary in how they apply it to conservatory conversions. We agree the specification with building control before ordering and apply on your behalf, then hand over the completion certificate once the work is signed off. Planning permission is not normally needed because the footprint and height do not change, though listed buildings and conservation areas should check with the council first.
Questions people ask
What happens to the old glass units?
They are lifted out by hand, taken away and recycled. Removal of the old roof is included in the price.
Would self-cleaning or solar control glass fix my hot conservatory?
It helps a little with glare and dirt, but it still lets direct sun through the roof. An insulated roof blocks the direct sun on the roof completely, apart from any roof lights you choose.
Can I replace only the misted glass units?
Yes, single units can be reglazed, and that is worth doing if the rest of the roof is sound and you are happy with the room. If the room is too hot or cold, spending on new units does not change that.
Will panels make my glass-roofed conservatory quieter?
Yes. Glass is quieter than polycarbonate, but the 75 mm foam core in our panels damps rain and hail noise further still.
Is a glass roof heavier than an insulated panel roof?
Usually, yes. A double glazed unit of two 4 mm panes weighs about 20 kg per m², and our panels weigh less than the units they replace.
