Remember my bathroom remodeling project? I took the liberty of gutting our outdated, decaying bathroom while my wife was out of town in April. I found some interesting air leakage pathways when I opened the walls. I fixed that. I found termite damage. I fixed that.
Our 1970 condo didn't have an exhaust fan in this bathroom because, hey, who needs a bath fan when you have a window? I fixed that. Here's how.
from Building Science http://www.greenbuildingadvisor.com/articles/dept/building-science/installing-exhaust-fan-during-bathroom-remodel