A case study of a home in Schaumburg, IL
Why in the world would your bathroom exhaust fan blow directly into your attic space!?! Great question!!! We receive calls nearly every day from people with attic mold issues. Just like the one pictured above in Schaumburg, IL. Attic mold is ALWAYS a result of some underlying root cause issues. Bathroom exhaust fans blowing directly into the attic can be one. Crazy, right??? For decades builders exhausted the fans directly into the attic. Thankfully, modern building practices have moved away from this malpractice. Unfortunately, there are existing homes all over Chicagoland that have not been corrected.
Moving hot moist air from one space of your home to another??
The whole point of the bathroom exhaust fan is to move hot/moist air OUT of your bathroom. Oddly, no one ever thought that moving that moist air out of your bathroom and into your attic was a problem!! Imagine with me for a second that you too live in Schaumburg. It is 28 degrees outside and all of the components of your roof are FREEZING COLD. What do you suppose would happen if you were to take a 4 inch tube and use it to blow hot moist air all over the ICE COLD underside of your roof!?! You guessed it……condensation, frost, and ultimately MOLD!!
So how should a bathroom exhaust fan work then!?!
It is shockingly simple. There should be an insulated vent line that runs directly from the top of your bathroom exhaust fan to a dedicated vent on your roof. NO, you can’t just take a tin line and kind of point it at one of your mushroom vents. NO, you can’t just shove the line down into your eave and pray the hot air gets out!! The line needs to be tied DIRECTLY to a boot that comes through your roof from the installed vent above! Simple!! Yet millions of homes all over Chicagoland have MULTIPLE bathroom exhaust fans blowing DIRECTLY into the attic.