How To Drill A Hole In A Roof!
Actually, this is part of the on-going full bathroom remodel but it does feature drilling a hole in our roof so...
We are finally going to have a properly-functioning bath fan because 1) we over-sized the fan, 2) we have a very short run of 6 inch diameter duct and 3) we are venting up through the roof using a large high-quality vent hood. The American Dream isn't home ownership, it's a bathroom ceiling free of mold!
Here's how I did it (your scenario might well be entirely different so don't follow me, I'm lost too).
After ensuring from underneath the location of my proposed hole with respect to where the duct was coming up from below, I drilled a small hole up through the roof sheeting and metal. I then layed out where my vent hood would go, based on that hole and equidistant between two ribs of the standing-seam roof (breaching a standing seam is to be avoided at all costs):
Using a carbide-tipped hole saw, I drilled through the metal roofing and mostly through the wood roof sheeting:
Next I used my handy Rockwell Versa-cut saw and metal blade to cut the roofing out to fit the dimensions of the vent hood and then finished removing the roof sheeting that I'd cut with the hole saw:
I then slid the base of the vent hood under the metal roofing such that the latter would now act as flashing. The bottom portion of the vent hood base would overlap the roofing, acting as flashing there.
Next I fasten all down using rubber-washered roofing screws and then caulked the whole works with roofing caulk:
Jennifer says, "Sure, that's nice, but not nearly as difficult as drilling a hole in a rock!"