People ask about price before they ask about anything else, and fairly. We do not quote figures on this page, and the quote we write after the survey stays fixed in writing. What we can set out here is what moves the number, so you understand why two houses on the same road get different answers.
Size comes first. A larger opening means longer timbers, a bigger unit and a wider light well. Next is the roof covering, because slate and the two kinds of tile all take different flashing. Access matters too. A low roof reached from a driveway is a simpler job than a tall one reached over an extension. The ceiling below counts as well. A clean reveal, plastered and painted, needs more work than a simple lined shaft.
Glazing choices add to the unit. A laminated pane is tougher and quieter, a coated pane holds heat in, and an electric opener means a motor plus wiring. A blind, in blackout or pleated form, completes the window.
Finally there is the question of how many windows. Two windows ordered for the same job share access and a single visit. Some households pair one over the table with another above the kitchen worktop or the stairs, and it is worth saying so at the survey, as both can sit on one fixed quote.
Timing plays a part as well. If the room is about to be redecorated or fitted with a new floor, it makes sense to fit the window first so the finishing is done once. We are glad to fit in with a decorator's dates and say so when we agree the visit.