I'm building a duplex with two interior bathrooms in each unit (no windows). To do what I can to control moisture when it is tenant occupied, and totally dependent on mechanical ventilation, I have installed higher end bathroom fans that will automatically come on when sensing humidity and will supposedly move 110 CFM.
I'm wondering what is the best way to supply make up air in a bathroom where the door will be closed when the fan is going (shower time) and no return air supplied (because it is a bathroom) to make it possible for the fans to do their job without starving for air. What would you do? The units should be fairly tight, infiltration wise. I have not yet had a fresh air supply to the return of the air handler installed but am seriously considering having that done.
Anyone know how many CFMs a decent bathroom vent fan can pull under a 2' 8" door with a 1" gap at the bottom if there is make up air available outside of the bathroom?
BTW, not sure how it is elsewhere in the country, but around here the bathroom vents are usually installed and supplied by the electrician.