I had a ceiling leak, between the first and second floor, where a vent pipe from an upstairs bathroom exist. I had a plumber in to find the cause of the leak and his diagnosis is that the vent pipe had sufficient condensation on it, to cause an accumulation of water, thus a leak. He suggests that I put an air vent in the ceiling to allow air to flow into the cavity between the rafters and to help keep the area warm and dry. Does this sound right? Is there an alternative to putting a louvered vent into the ceiling? Since the ceiling has been opened, there no longer exists any condensation.