How Much Does a Triple Glazed Rooflight Cost?
A triple glazed rooflight, supplied and fitted in the Ipswich and Suffolk area, runs from roughly £1,850 for a small pitched roof window up to £7,400 for a large roof lantern, sitting a few hundred to a couple of thousand pounds above the double-glazed equivalent depending on size. The extra buys a whole-unit U-value of 0.7 to 1.1 W/m²K and a warmer inner glass surface. On top of the unit price, triple can carry a structural surcharge on a retrofit, because it adds about 40 per cent to the glass weight and sometimes forces a heavier opening detail. This page gives the installed ranges and the surcharges honestly.
No other installer in Suffolk publishes these figures. We do, because three quotes with no common basis is not a comparison.
Installed price by size
Supply and fit, in the Ipswich, Suffolk and north Essex area, for a thermally broken triple unit with a warm-edge spacer, a new insulated upstand, airtightness and vapour control detailing, weathering and internal trims. Single storey, reasonable access, sound structure. The double-glazed column is shown alongside so you can see the step.
| Unit and size | Double glazed, supply and fit | Triple glazed, supply and fit | Days on site |
|---|---|---|---|
| Pitched roof window, 780 x 1180mm | £1,400 to £1,900 | £1,850 to £2,500 | 1 |
| Pitched roof window, 1140 x 1180mm | £1,700 to £2,300 | £2,250 to £3,000 | 1 |
| Flat rooflight, 1.0 x 1.0m | £2,100 to £2,900 | £2,700 to £3,600 | 1 to 2 |
| Flat rooflight, 1.5 x 1.0m | £2,600 to £3,500 | £3,300 to £4,400 | 2 |
| Flat rooflight, 2.0 x 1.2m | £3,300 to £4,500 | £4,200 to £5,600 | 2 |
| Roof lantern, 2.5 x 1.5m | £4,600 to £6,000 | £5,600 to £7,400 | 2 to 3 |
The pattern is that the triple premium grows with size, from a few hundred pounds on a small pitched window to a couple of thousand on a large lantern, because there is more glass to add the third pane to.
The structural and handling surcharges
The unit price is not the whole story on triple, because the weight has consequences:
- Structural upgrade on a retrofit. The extra 40 per cent of glass weight can push a retrofit opening from doubled trimmers into needing a ring beam or a steel. Where that happens it can add several hundred to a couple of thousand pounds, sometimes more than the glazing premium itself. This is why we check the structure at survey before recommending triple on an existing roof. The detail is on triple glazed rooflight installation.
- Structural engineer’s calculation, a few hundred pounds, where the opening is over 1.5m or the roof is an unknown quantity. The cheapest insurance on the job.
- Handling and access. A heavy triple unit sometimes needs more hands or mechanical lifting, especially a large lantern, which can nudge the labour up on a difficult access.
The surcharge can outweigh the saving. On a marginal retrofit roof, the structural work triggered by triple’s weight can cost more than the energy it saves over many years. That is exactly the case where a good solar control double unit is the sensible answer. On a new opening designed for the weight, there is no surcharge, so triple is a cleaner decision. We tell you which situation you are in at survey.
How it compares with a high-performance double
Against a solar control double unit at 1.2 to 1.4 W/m²K, triple gets you down to 0.7 to 1.1 and a warmer inner surface, for the premium in the table plus any structural surcharge. Whether that is worth it depends on the roof: yes on large units, north-facing roofs and low-energy builds, no on small units, sunny aspects that overheat, or marginal structure. The decision is set out on is triple glazing worth it for a rooflight and compared in full on double or triple glazed rooflights, what the numbers say. On a south or west-facing roof that overheats, note that a solar control double often beats a clear triple, so paying the triple premium there can actually give you a hotter room.
How much does a triple glazed rooflight cost installed?
In the Ipswich and Suffolk area, roughly £1,850 for a small pitched roof window up to £7,400 for a large roof lantern, supply and fit with a new insulated upstand and full detailing. That is a few hundred to a couple of thousand pounds above the double-glazed equivalent, with the premium growing with size. On a retrofit, add any structural surcharge, because the extra weight can force a heavier opening detail. Your survey gives one fixed price for your exact unit.
Why is a triple glazed rooflight more than the glass alone suggests?
Because the weight has knock-on costs. A third pane adds about 40 per cent to the glass weight, which on a retrofit can push the opening from doubled trimmers into needing a ring beam or a steel, and that structural work can add several hundred to a couple of thousand pounds. There may also be a structural engineer’s calculation and heavier handling. On a new opening designed for the weight there is no surcharge, so triple is cheaper to justify there than on a marginal existing roof.
Get triple priced with the structure checked
We quote triple and high-performance double side by side, check whether your structure carries the weight, and put any surcharge on the quote plainly rather than as a surprise. One fixed price, a 10-year workmanship guarantee, and installers with 25 years on rooflights.
Request a fixed quote, read the published prices, or start from energy efficient skylight installation.
Thinking about this job? We survey across Ipswich, Suffolk and north Essex and give you a fixed price before any work starts, with a 10-year workmanship guarantee.