The last issue of Fine Homebuilding discussed installing a bathroom fan. It suggested venting through the roof or a gable end wall, not the soffit because moist air would re-enter the attic through the soffit vent. There is no gable end wall near my bathroom. Can I go through the roof in a cold climate (Saskatchewan, Canada)? Wont the flapper freeze shut? What about heat loss? Do I have to climb on the roof to sweep snow away from the vent? By the way, I have a chimney and an open stack in the roof and a wall vent for the dryer if this sheds any light on the situation. Also there is a vent for the attic in the gable end wall. I don’t know if the soffit is vented but it is covered with some kind of perforated metal cladding that was installed when the house was sided in vinyl. The house was built in 1950. I know that bathroom fans are common here. In fact, I think that a fan or a window is required by code. Any observations?