Show us a bathroom with peeling paint, rotting window trim and a mold problem and we'll show you a bathroom without a vent fan. Bathrrom ventilation is the best way to prevent moisture-related problems, such as the growth of mold and mildew. Here, This Old House general contractor Tom Silva shows the proper way to install a fan, running the exhaust duct into the attic and through a sidewall to the outdoors.
Other venting options includes running the duct up through the roof or down through the soffit. Note that the fan must always exhaust to the outdoors; never allow the duct to simply blow into an attic, crawlspace or other enclosed area, or you're certain to fail inspection.