Originally Posted by vwboomer
as I said, no eves so I can't go anywhere but roof. Which I spose I could do. little leery of what a 4" hole saw is gonna do to old fiberglass shingles. I guess with enough flashing and goop it shouldn't be a problem.
Make sure your hole saw is sharp and the shingles aren't cold and you should be OK. This is the roof vent I used:
which comes with its own flashing, so you just need to cut the shingles to fit and goop the seams. I didn't use the included duct, since I had 4" insulated duct already. In my case, since I had a package of shingles on hand, I went ahead and replaced all the shingles around the new opening. I did have to use a 5" hole saw so there would be room for the duct insulation and the clamps.