Thanks a lot for the help. It would seem that the little shopping trolley in the instruction manual is therefore code for "optional". cryptography at it's best! I will reduce the size of the suggested opening to take just the window frame, allowing enough "play" for the flashing kit.
Hello. New to this forum so please bear with me.
I have read through some past threads but can't find an answer to my question. I have 2 new GGL Velux windows to fit. Just had a confusing hour or so with the installation manual and am none the wiser as to the function of the insulation...