Bathroom exhaust fan question
Definitely to the outside. We had a serious mold problem in a hallway closet and wondered why. It turns out that the house had settled and the top of the wall in the closet had separated from the ceiling. The door to the closet happens to be in the same area as the HVAC return...and...the hallway bathroom exhaust fan vented into the attic in the direction of the hallway closet.
So, near as I can figure...the moisture from the exhaust fan, after baths, was pulled into the closet by the HVAC return...and created a moist, mold loving environment.
Fixed and gone...