I do not want to install an extra vent specifically for bathroom so I was wondering if I could use one of the existing top ones. It looks like from underneath there is a circular hole that I can push a duct in. The roof vents don't leak so they are solid even with really crazy rain, hail snow etc.
Can I install on existing vent? If yes, do I have seal it after pushing the vent in so that no humidity will return back down to the attic? What's the best way to go about doing this?