Bathroom Exhaust Fan Ducting

drtpdee · 03-03-2008, 07:00 PM

I am in the process of finishing my basement. We have a rough-in for a bathroom that I will finish in the future. The bathroom will also house the laundry (washer and gas dryer - vented to the rear of the house via rigid metal ducting). The bathroom/laundry is about 70 to 80 sq. ft. and I only plan to add a pedestal sink and toilet - no shower. That said, I have the fan housing (70 cfm fan) installed and am planning the run to the front of the house - through the rim joist and siding. Aside from the issues I have with getting the flat exhaust cover to work on lapped siding, my ultimate questions are

1.) Should use the flexible insulated ducting? I purchased some but haven't installed it. The run is only about' 8 to 10' with no bends. The cover I have has the louvered damper flaps and I live in the Northeast.

2.) If the ducting is insulated and I add some insulation in the joist space + there is insulation at the rim joist, should there be any concern about condensation and mold, especially if there is no shower in the bathroom?

ANy advice is appreciated. Thanks!!

tnthvac · 03-03-2008, 07:47 PM

Quote:

Originally Posted by drtpdee

I am in the process of finishing my basement. We have a rough-in for a bathroom that I will finish in the future. The bathroom will also house the laundry (washer and gas dryer - vented to the rear of the house via rigid metal ducting). The bathroom/laundry is about 70 to 80 sq. ft. and I only plan to add a pedestal sink and toilet - no shower. That said, I have the fan housing (70 cfm fan) installed and am planning the run to the front of the house - through the rim joist and siding. Aside from the issues I have with getting the flat exhaust cover to work on lapped siding, my ultimate questions are

1.) Should use the flexible insulated ducting? I purchased some but haven't installed it. The run is only about' 8 to 10' with no bends. The cover I have has the louvered damper flaps and I live in the Northeast.

2.) If the ducting is insulated and I add some insulation in the joist space + there is insulation at the rim joist, should there be any concern about condensation and mold, especially if there is no shower in the bathroom?

ANy advice is appreciated. Thanks!!

If you want to use the insulated duct since you already have it, it would probably help with heat loss since it is between floors. As far as the condensation goes, I don't see why you would have any problem with it if you have a vent cover and cold air can't get back in.