In brief
The cost of fitting a roof lantern is set by the lantern itself, its frame material and glazing, whether a new kerb has to be built, and how the crew reaches the roof. Because those vary so much between houses, we price from a survey and send a written quote, with no standard figure to quote over the phone. Two lanterns of similar width can sit well apart once these are counted.
- Size: the footprint, the ridge height and the number of glazed panes
- Frame: aluminium or uPVC, the finish, and the slimness of the profile
- Glazing: the glass specification, solar control and self-cleaning coatings
- Kerb: a new one to build, or an existing one to check and use
- Access: scaffold, lifting gear and the route for heavy glass
What a lantern quote is made of
A roof lantern is a glazed structure on a flat roof, with sloping sides and a ridge, built up from a frame, glazing bars and sealed panes. A quote for one is really several prices added together: the lantern as made by the manufacturer, the kerb it stands on, the work to fit it, the access needed, and the finish inside.
We split the quote into those parts so you can see which of them moves when you change your mind. If you swap a frame finish or alter the size, only the relevant lines change. Our general page on rooflight costs explains the cost factors across all our rooflight types, and this page covers the points that are specific to lanterns.
Size and shape of the lantern
Size is the first driver. A larger footprint means a longer frame, more glass and a heavier unit to lift. Height matters as well, since a steeper pitch on the glazed sides adds frame and glass. The number of panes follows from the shape, and each one is a sealed unit made to the lantern's drawing.
Shape changes the price too. A simple rectangular lantern with a single ridge is less complicated to make than a hipped lantern with a pyramid roof, or one with an unusual outline to follow a bespoke kerb. Corner details, ridge finials and decorative cresting each add to the work in the factory.
For help in choosing a size to suit the room and the structure, see our guide to roof lantern sizes and kerb dimensions.
Frame material and finish
The frame is a large part of what you pay for. Aluminium frames can be made with slim sightlines and a powder coated finish in a colour of your choice, and they are the usual choice where the lantern is a feature of the room. uPVC frames are made differently, tend to have thicker profiles and are offered in a narrower range of finishes.
Colour affects the price. A standard colour is quicker for the maker than a bespoke one, and a different colour inside and out adds a further step. Our comparison of aluminium and uPVC lanterns sets out how the two differ so you can weigh the price against the look.
Glazing choices
Glass is the other major variable. A standard double-glazed unit costs less than a triple-glazed one, and each coating adds to the price: solar control to reduce heat gain in a south-facing extension, self-cleaning for panes that are hard to reach, and a tint or a low-reflection finish for appearance.
Opening lanterns, where a vent is built into the glazed side and operated by hand or by motor, cost more than fixed ones, and a rain sensor and electric control add again. If you want the lantern to help move warm air out of the room, say so at the survey and we will price the vent as a separate line.
Performance has to meet the current rules for the type of rooflight, and the glass specification named in your quote is chosen with that in mind.
The kerb, the roof and the way in
A lantern sits on a kerb, and there are two possible situations. On a new extension the kerb is part of the roof being built, and it is formed by the carpenter to the sizes we supply in writing, which keeps the cost down because the work happens once. On an existing flat roof, a new kerb has to be built, the joists trimmed and the covering cut back and made good, which adds time and sometimes a roofer's visit.
Access can be a large line. A single-storey extension with a clear side route might need only a tower and a few hands. A taller house or a tight garden might need scaffolding or a crane or lifting arm for the glass. We state in the quote what access has been allowed for.
Inside, the lantern needs lining, and the reveals are plastered and decorated. If your builder and plasterer are already on site, we agree who does what so the same work is not paid for twice. If you are looking at an existing roof, read about fitting a lantern to a flat roof that is already covered.
How the written quote is produced
We start with a free survey. We measure the opening or the kerb, look at the structure, check the access and talk through the glazing options. From that we write a quote that names the lantern, its frame and glazing, the manufacturer's quoted wait, the access allowed, and the points to be settled with your builder.
If your project is still on the drawing board, a price can be worked from the plans and checked against the opening once it exists, and a lantern can be compared with a large flat rooflight in the same quote. Because a lantern is made to measure, we place the order once the size is settled, and the maker's acceptance fixes the date that you and the builder both receive. For how the work fits into a build, see the roof lantern installation service, or read how long the fitting itself takes in our answer on fitting time.
