How Much Does a Roof Lantern Cost, and What Size Should It Be?
Updated: 8 hours ago
An aluminium roof lantern typically costs £1,500 to £2,500 for a small lantern, £2,000 to £3,500 at around 1.5m x 2m and £3,500 to £7,000 for a large one, supplied and fitted including VAT, with hardwood costing more. The price is driven by four things: the lantern's size, its frame material (aluminium or hardwood), the glass specification, and whether the roof already has an opening for it. A small aluminium lantern on a new extension sits at the lower end; a large hardwood lantern cut into an existing roof sits at the top. On an existing flat roof, the structural opening, the upstand and the making-good inside can cost as much again as the lantern itself.
We design and fit roof lanterns in aluminium and hardwood, and quote each one after seeing the roof.
Typical UK prices
Supplied and fitted, including VAT, onto a ready upstand:
Small aluminium lantern, around 1m x 1m: £1,500 to £2,500.
Medium aluminium lantern, around 1.5m x 2m: £2,000 to £3,500.
Large aluminium lantern, around 1.5m x 3m to 2m x 3m: £3,500 to £7,000.
Hardwood lantern, around 1.5m x 2m: £3,200 to £4,500.
Extras: an electric opening vent £750 to £3,000; lantern blinds around £2,500.
Premium systems sit toward the upper end; a new opening in an existing roof is extra. These are typical UK market prices from published cost guides as of 2026; bespoke designs are priced after a survey.
How does size change the cost of a roof lantern?
Roof lanterns are priced by their footprint and their specification. Three sizes cover most projects.
A small lantern of around 1m x 1.5m suits a flat roof over a hallway, a bathroom or a narrow side return. It brings light into a room that would otherwise have none from above, and in aluminium it is the least expensive lantern to supply and fit.
A medium lantern of around 1.5m x 2.5m to 2m x 3m is the size most kitchen extensions take. It is large enough to light a room of 20 to 30 square metres and to read as a feature rather than a rooflight. It is the size where most budgets for a lantern are set.
A large lantern of 2m x 4m and above belongs on an orangery or a substantial extension. At this size the lantern is a piece of architecture, the glass panels are large, and the structure carrying it needs to be designed for it, so the cost rises with both the glass and the engineering. In hardwood, which is what a traditional orangery calls for, it costs more again than the same lantern in aluminium.
Our guide to orangery roof lanterns covers the particular rules that apply when the lantern sits on a brick-built orangery.
What size roof lantern should you choose?
The proportion rules are simple and they matter. As a rule of thumb, a lantern's glazed area is about a quarter to a third of the ceiling it sits in, adjusted for orientation and room use. Smaller than that and it looks like a rooflight that has been given ideas; larger and the roof around it looks like a rim.
Most manufacturers make lanterns to measure, but common off-the-shelf sizes typically run:
1000mm x 1000mm and 1000mm x 1500mm for halls, bathrooms and side returns.
1000mm x 2000mm and 1500mm x 2000mm for smaller kitchen extensions.
1500mm x 2500mm, 1500mm x 3000mm and 2000mm x 3000mm for larger kitchen and living extensions.
2000mm x 4000mm and above, usually made to order, for orangeries.
Sizes are normally quoted to the outside of the upstand, so check which dimension a supplier means before comparing prices.
Leave a clear margin between the lantern and the roof edges, and between the lantern and the house wall. On a rear extension, a margin of at least 600mm to the parapet or fascia gives the lantern room to read as an object and gives the roofer room to weather it properly.
Height follows footprint. A lantern's ridge height is set by its pitch and its width, and a wider lantern is a taller one. On a single-storey extension under a first-floor window, the height available is the limit on the width, and a long, narrow lantern is the answer.
Inside, the lantern should sit over the part of the room where the light is wanted: the table, the island, the seating. It is worth drawing the furniture on the plan before fixing the position.
What does a lantern roof cost to install?
The lantern price is the supply-and-fit of the lantern itself. The roof has to be ready for it, and that is where the rest of the money goes.
On a new extension, the structural opening is designed in and the upstand is built as part of the roof. The cost is absorbed into the roof and is modest.
On an existing flat roof, the opening has to be cut, trimmed with new structural timbers or steels, and an insulated upstand built to lift the lantern above the roof surface. The roof covering is then dressed up the upstand and the ceiling is made good inside. This work can cost as much as the lantern itself, and more if the roof structure needs reinforcing, so it belongs in the budget from the start.
Building regulations apply to a new opening in a roof, because it affects the structure and the thermal performance. A structural engineer's calculation for the trimmers is usually needed and costs around £300.
What changes roof lantern prices?
Material comes first. Aluminium is the standard for modern extensions: slim, strong, thermally broken and available in any colour. Hardwood suits period buildings and traditional orangeries, costs more and needs decorating. Both are made to order.
Glass comes second. Double glazing is standard. Solar control glass, which keeps a south-facing room usable in summer, is the upgrade most worth paying for. Triple glazing improves winter performance and adds weight. Self-cleaning coatings are useful on a roof that cannot be reached.
Configuration comes third. A simple hipped lantern with four sloping faces is the base. A lantern with a ridge and more glazing bars, a lantern with opening vents for ventilation, or one with integrated blinds each add to the price.
Size is last, and it is nearly linear once the structural work is accounted for.
Roof lantern vs skylight: which costs more?
A roof lantern costs more than a flat skylight of the same footprint: more frame, more glass faces and a taller upstand. A skylight sits flush and brings light straight down, and is usually the right, cheaper answer over a hallway or bathroom. A lantern brings light in from four sides, gives the room height and a focal point, and earns its extra cost over a kitchen or living room. Our guide to orangery roofs and features shows the ways a lantern can be used.
What should a roof lantern quote include?
Two quotes for the same size lantern can differ widely because they cover different work. Check that each one states:
The lantern size, and whether it is measured to the upstand or the glass.
The frame material, colour and whether it is thermally broken.
The glass specification: low-emissivity, solar control, self-cleaning, laminated inner pane.
Vents, blinds and lighting, if wanted, and the electrics to power them.
The structural opening, trimmers, engineer's calculation and upstand on an existing roof.
The roofing work around the upstand and the making-good of the ceiling inside.
Building control, which applies to a new opening in a roof.
On a south-facing roof, budget for solar control glass and an opening vent from the start; they are cheaper to design in than to add.
Roof lantern questions, answered
How much does a roof lantern cost supplied and fitted?
Typically £1,500 to £7,000 for an aluminium lantern, small to large, including VAT. The price is set by the lantern's size, its frame material and its glass, plus the structural work if the roof is existing. A small aluminium lantern on a new extension costs least; a large hardwood lantern cut into an existing roof costs most, and there the opening and upstand can match the cost of the lantern itself.
Can a roof lantern be fitted to an existing flat roof?
Yes, provided the roof structure can be trimmed to take the opening. An engineer checks the timbers or steels, an insulated upstand is built and the covering is dressed up to it. Our guide to roof lanterns for flat roofs covers the retrofit in full.
Do roof lanterns leak or overheat?
A well-made lantern on a properly built upstand does not leak. Overheating is a matter of glass: solar control glazing keeps a south-facing lantern comfortable, and opening vents help.
Aluminium or hardwood roof lantern?
Aluminium for modern extensions and most kitchen projects: slimmer, lower maintenance, any colour. Hardwood for period houses and traditional orangeries, where the joinery is part of the design. Our guide to orangery roof lanterns covers ventilation and blinds for a lantern that takes full sun.
Talk to our design team
If you are weighing up a lantern, talk to us about your project and we will advise on the material and the size.
