This is a classic winter time style of leak that I service often. This is condensation build up. In this particular case warm air is escaping through a skylight chute in a bathroom, right over a shower and entering the attic bc of a bad vapor barrier and insulation install. The home owners naturally think that their roof is leaking but when warm air enters a very cold attic it condenses into water and creates leaking, and sometimes mold and wood rot.
