Ceiling Fans in Bathrooms

by John
(Michigan)

I have a ceiling fan in our bathroom that vents into the attic. Should this be vented to the outside and if so, can I run a line to my soffit or do I have to go through the roof.

Answer: I believe you have a bathroom exhaust fan. The purpose of this fan is to get rid of dampness/moisture in the bathroom. Most builders simply vent into the attic because it complies with building codes. The more moisture you can vent to the outside, the dryer your attic will be and the less mold there will be because of the reduced moisture.

Taking the vent to the eave is better than nothing, but not as good as thru the roof. There are special vents with built in dampers to prevent back drafts. Keep the pipe short and use the least amount of bends possible. Bends restrict air flow. A timer to allow the fan to stay on for a short time after you exit the bathroom is a good idea.

Dave