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TOPIC: Skylights and Bay windows

Skylight and Roof Vent 101

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Hello, Looking for a little basic theory put in laymen's terms about flashing, transitions and edges with metal roofing. I'm sure most of you remember this? Both the skylight manufacturer and a custom flashing/metal roof parts company have told me that this type of **self-flashing skylight** will not work with a metal roof and was primarily designed for comp shingles. Many have told me that a curb mounted skylight or vent is the ONLY method to use with metal roofing. Also, the ONLY method described in the ASC specs appears (with my limited grasp) to be for a curb mounted skylight. So the question at this point is if I rip these out and eat the cost OR attempt to make my own custom flashing? After all, the other Velux skylights we are installing on a different pitch are deck mounted but come with a multi piece flashing kit specifically designed for metal roofing. Why couldn't I just have a sheet metal shop produce something that accomplishes the same thing for the two problematic self-flashing 2'x2' bubbles? I realize it is never a good idea to go outside that manufacturer specs, but by that same logic, wouldn't the Velux models be considered outside the ASC spec by that methods omission from the plans? I have no doubt, however, that the Velux models will work and never leak. Can a method of flashing (keeping in mind the pictures from the link) be created for these self-flashing 2'x2' bubbles? Yes? No? Or is my only route is to rip the suckers out and put in a curb type skylight? Also, should I replace the vents with curb mounted roof vents too? Thanks for your patience, Tim
Guest User

10/10/2003
It should be possible to build up a curb and flash it appropriately using these skylights.
Todd Miller
Isaiah Industries, Inc.

10/12/2003
What should be used? An asphalt shingle contractor told me that the standard practice for metal roofs is to use silicon, and that it doesn't hold up.
Lee Harp

7/19/2004
The standard practice is to have a skylight on a curb with roof flashing which extends up the sides of the curb and under the "cap" of the skylight. This flashing then extends out from the sides of the skylight for 12" or so and also up above the skylight for 18" or so, being received under the underlayment. On horizontally-run metal roof panels, the top and side flashings are made so that they bring water back out on top of the roof panels. On vertical run metal roofing panels, the panels lay on top of the flashing and, on the sides, a second flashing is installed on top of them. The downhill side flashing runs up the curb and also out and across the roofing.
Guest User

7/19/2004
Hey would you be able to make a diagram of what you feel is correct.
Guest User

6/21/2010