Two rooflight quotes for neighbouring houses can be far apart without either being wrong. The differences come from the roof, the glass and the way into the loft, and a free survey finds them before any figure is written.
Listed or sensitive roofs need a type of rooflight that sits flush with the covering, such as a conservation rooflight, and these cost more than a standard roof window. Newer houses with machine-made tiles take a standard unit and an off-the-shelf flashing kit.
Size has an obvious effect, but so does shape. A tall, narrow window and a wide, short one can have the same area and need different framing. The pitch of the roof controls how much of the opening is visible from inside and how far the window is from head height.
The things you can influence
Some factors are yours to choose: the glazing grade, the opening method and the blind. Others are set by the house, like the roof covering and the access. We separate the two in the quote, so you can see what is a choice and what is a given.
No figure appears on this page because the right one depends on all of this. After the survey you get one fixed written quote, and that figure is the one on the day.