Bathroom ceiling fans that vent directly into an attic will move an immense amount of moisture laden air from the home’s interior to the attic. This can result in serious consequences, especially during cold winter months. Excessive moisture in attics can reduce the effectiveness of the attic’s insulation, cause condensation to occur within the attic, cause premature deterioration of the roof decking, cause shingles and underlayment on the roof to pucker up, contribute to mold growth, etc. For these reasons we advise that bathroom ceiling fans be exhausted to the exterior of the home instead of directly into the attic. To properly vent bathroom ceiling exhaust fans we advise the ceiling exhaust fans be connected to roof exhaust vents by insulated flexible duct, run the insulated ducts the shortest distance possible (less than ~12-feet), and connect them to plastic roof exhaust vents. Avoid connecting ducts to the home’s existing soffit vents (a.k.a. undereave vents) because undereave vents are “intake” vents, so much of the moisture laden air exiting the duct will be drawn back into the attic if exhausted at these “intake” vents. Also avoid connecting the ducts to existing metal passive roof vents because the moisture laden air may condensate when it makes contact with cold metal roof vents and then drip back in to the attic.

Roofing Resources

You may be interested in some of our Visual Aids Roofing Resources. Visual aids can be of great assistance when roofing a house for a variety of reasons. Since “a picture is worth a thousand words” we’ve included some roofing photos to help in those instances when a picture would make it so much easier to explain a certain issue. For example, we frequently find it necessary to propose the installation of kick out flashings.