How much does a roof window cost to fit?

A roof window, which the trade also calls a rooflight, is priced by its parts. A larger window means more glass, a bigger frame and a wider opening in the roof, so size moves the price first. The way it opens comes next. A manual centre-pivot or top-hung window is the simpler build; a window with an electric or solar motor adds the motor, a control and the cable or panel that goes with it. Electric models from some makers carry a rain sensor. Our guide to opening types compares the two manual styles.

The energy rules sit inside the glass choice. In England a new roof window in an existing home should have a U-value no worse than 1.4 W/m²K, or a Window Energy Rating of Band B or better, so the glazing is part of what is bought rather than an add-on. Makers sell different glazing within a range: solar control coatings for a room that catches summer sun, and easy-clean coatings that the maker says help rain wash dirt away. Each choice changes the price of the unit.

The flashing kit is the set of pieces that joins the frame to the roof around it. It is matched to the covering: thin slate, plain tile or a profiled concrete tile each take a different kit, and a window set lower into the roof may call for a recessed one. That is why a window of the same size does not cost the same on every roof. The covering is examined during the survey, so the kit is chosen before ordering. See flashing for slate and tile.

A blind is made for one maker and one size code, and a bathroom or bedroom blind is a different product from a kitchen one. A motorised blind costs more than a manual one. On the roof side, reach matters: a tall house with no side path to the back may need a scaffold tower or similar equipment to carry the window up, while a low roof approached from clear ground may not. Blind controls play a part as well: a cord or pole costs less than a motor, and a motor needs a cable route to the window, which is easiest to plan early.

Taking one window out and putting another in the same hole involves less roof work than cutting a fresh opening, because the rafters are already trimmed. A bigger window, or one in a new position, means cutting and trimming rafters, which adds work. A job that changes only the glass, or a window within its existing frame, is not a controlled fitting, which is separate work from fitting a whole new unit. Whatever goes in as a replacement element should be no worse than the part it replaces. Where the old window still has its label, a photo of it helps with the size code.

In England, planning rules usually treat a roof window on a house as permitted development, inside limits, so a planning application is not normally part of the price; our planning permission guide gives them. Where the work is notifiable, we handle the Building Regulations notification with the council's building control team or a registered building control approver. On approval, the position is that a new rooflight generally needs it, and a swapped roof window usually does.

Inside the room, a lining runs round the window, where the rafters were cut and the plasterboard returns to the glass, with insulation behind it. A deeper roof, or an old opening of a different size, changes how much lining is built. When you compare quotes, check whether each one ends at plaster or goes on to decoration, since that is one reason two figures differ.

A picture shows the window you like but not the rafters, the covering or the way in. Nothing is quoted off a photo alone: the free survey is first, and the fixed written quote arrives afterwards. Photos to WhatsApp 07880 284133 give us a head start. For the labour there is a 10-year workmanship guarantee. For every product side by side, see the costs page; the roof windows page covers this range.