Options for venting a bathroom exhaust fan include best to worst.
Bath fan vents into attic.
The exhaust vent must terminate outdoors.
You should never exhaust the bathroom fan directly into the attic.
First you ll partially block your roof vent with the piping reducing the flow of cooling air through your attic.
If you re tempted to vent your exhaust fan through an existing roof vent or even vent it into the attic don t do it.
It seems like such an easy solution just leave a bathroom vent hose in an attic.
Otherwise you re inviting a moisture mold rot insect problem in the building.
Through the roof or an exterior gable wall.
Do not simply terminate a bath vent fan duct in an attic as shown in our photo above nor can you just dump the exhaust vent into a crawl space nor into a closed wall floor or ceiling cavity.
Second during cold winters you ll be blowing warm moist air onto a cold surface the roof vent and roof plywood.
Your attic is not a temperature controlled environment is never the same temperature as your living space and generally closer to the temperature outside.
It s all outdoor air anyways right.
Bathroom ventilation codes require a bathroom exhaust fan to vent to the exterior not the attic for health and structural reasons.
No you should not vent a bathroom fan directly into an attic.
However you can vent a bathroom fan through an attic while it terminates on the roof or gable end.