We had Anderson Velux roof windows professionally installed about five years ago. From day one they leaked and neither the contractor nor Anderson was any help. In fact one of Anderson's phone reps. told me that all Velux windows would leak and that they could not be disassembled and reglazed. I have tried untold numbers of caulks-from silicone to butyl - and the only thing that works is taping 3 mill plastic around them with duct tape. My brother in law - a marine mechanic says 3M caulk # 5200 or 5250 will stop a sub-water line leak. Should I try this or is there a better solution?

Velux Skylight