Bathroom Fan Vent Through Attic

Bath vent fan duct routing.

Bathroom fan vent through attic.

Duct already wrapped in insulation at home centers. When venting a bathroom exhaust fan make sure to vent the air to the outside rather than into your attic where it can cause mold and mildew to form. All municipalities have different requirements but some do not draw a hard line on requiring exhaust fans. The building code requires a bathroom exhaust fan to vent outside the building so installation of a new bathroom fan necessarily involves installation of ductwork.

Depending on the location of the bathroom it may be easy to vent the exhaust fan through the roof. Options for venting a bathroom exhaust fan include best to worst. Each fan vents separately out the roof. In order to accomplish this the roof has to have a hole cut in it.

Although this isn t always possible in attic crawl spaces you should always insulate the duct to prevent condensation problems. This involves running ductwork from the fan usually though an attic and out through the roof. In all cases the ducting needs to conduct the exhaust to the building exterior and needs to terminate in an animal proof vent cover. It seems like such an easy solution just leave a bathroom vent hose in an attic.

One in line centrifugal fan can be mounted in the attic to exhaust the moisture from two bathrooms. No you should not vent a bathroom fan directly into an attic. It is because of this that many builders tend to advise against this method. Let me tell you.

This article describes routing bath exhaust fan duct upwards through an attic or roof space or downwards through a floor or crawl space. You can find 4 in. You should never exhaust the bathroom fan directly into the attic. Your attic is not a temperature controlled environment is never the same temperature as your living space and generally closer to the temperature outside.

Through the roof or an exterior gable wall. This is much easier to do if you have attic access because if you don t you usually have to remove some ceiling drywall and run the ducts along a joist. Up through roof down through floor or crawl area. The best exhaust fan venting is through smooth rigid ducts with taped joints and screwed to a special vent hood.

However you can vent a bathroom fan through an attic while it terminates on the roof or gable end. Both bathrooms are vented by a single in line fan that has one exhaust vent running through the roof. It s all outdoor air anyways right. Surprisingly bathroom fans are not required by some building codes.

Bathroom code does address the issue of moving odor and moisture laden air from the bathroom to the outside.