You always order by daylight size: the clear opening visible from inside. Your new skylight fits straight away.
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Daylight size= your order size
The clear opening visible from inside. Measured along the inside of the curb, from edge to edge.
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Roof openingstraight curb = daylight size
The opening in your roof. With a straight curb (/00), it equals the daylight size. With a sloped curb (/20 or /30), it is 20 or 30 cm larger.
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External skylight size= daylight size + 160 mm
What you measure on the outside of an existing skylight. The flange extends 80 mm on each side. Subtract 160 mm to find your daylight size.
Sizing questions
What is the difference between daylight size and roof opening?
I am measuring my skylight from the outside. What do I order?
You already have a Skylux curb
You are creating a new roof opening
You have a curb from another brand
iWindow2 Flex flat roof windows
Replace your old skylight with an openable glass flat roof window, without demolition work. The iWindow2 Flex fits directly onto your existing curb. The motor is integrated into the frame and slides the window upward for ventilation. Sleek design, guaranteed watertight.





































