2500 × 4000 mm roof lantern
Prices, weight, rise and glass area for a 2500 × 4000 mm rectangular lantern, plus a drawing you can share with your builder.
Get a lantern price
Send your kerb size and we will reply with a fixed written quote.
In short: a 2500 × 4000 mm rectangular roof lantern covers 10.00 m² of roof, stands about 580 mm above the kerb and costs from £4,895 including VAT, supply only.
What does a 2500 × 4000 mm lantern cost?
Three common specifications, premium first. All prices are guides including VAT for supply only; your quote confirms the fixed price.
| Specification | Glass | Guide price, inc VAT |
|---|---|---|
| Premium | Triple glazed, neutral solar control | £6,695–£7,795£5,579 ex VAT from |
| Balanced suits most kitchens | Solar-control double glazing, neutral | £5,395–£6,295£4,496 ex VAT from |
| Essential | Self-cleaning double glazing, blue or clear | £4,895–£5,695£4,079 ex VAT from |
Aluminium, stock colour, supply only. Matching insulated upstand from £445; fitting this size to a ready upstand from £1,395. Fixed price on your written quote.
Questions about this size
Will a 2500 x 4000 mm lantern fit my kerb?
It fits a kerb whose outside measures 2500 mm by 4000 mm. Measure the outside of your kerb at several points and check the diagonals. If your kerb is a few millimetres different, we can quote made-to-measure instead.
How heavy is a 2500 x 4000 mm roof lantern?
Roughly 435 kg with double glazing and 585 kg with triple glazing, as a planning figure. The manufacturer's weight for your chosen range is on your quote.
How much light does a 2500 x 4000 mm lantern give?
It covers 10.00 m² of roof with about 11.03 m² of sloping glass. As a guide, that suits a room of roughly 40–60 m² of floor. In England, extensions are generally expected to keep all glazing (windows, doors and rooflights together) within about 25% of the floor area unless calculations justify more.
Does a 2500 x 4000 mm lantern need intermediate rafters?
Many ranges add an intermediate rafter at this length; the drawing on your quote shows the layout.