If you vent through a soffit where attic vents are often located the moisture will get sucked back up into the attic or roof venting.
Bath fan vented to attic.
All municipalities have different requirements but some do not draw a hard line on requiring exhaust fans.
Vent your bath and kitchen exhaust fans through the roof through a special roof hood.
This article describes routing bath exhaust fan duct upwards through an attic or roof space or downwards through a floor or crawl space.
The truth about attic bathroom venting.
In fact i have seen numerous houses that haven t yet had signs of mold with the bath fan venting incorrectly.
Bathroom ventilation fan duct routing routing a bath vent duct down out or up through an attic or roof out.
Venting through a roof vent or exhausting them in the attic could cause moisture problems and rot.
But while you can t have two fans with one vent you can make one fan and one vent serve two bathrooms.
Options for venting a bathroom exhaust fan include best to worst.
This setup requires an in line centrifugal fan mounted in the attic drawing air simultaneously from both bathrooms see photo.
If you vent the bathroom exhaust fan to close to the soffit vents which are vented plates under your homes outer edge and roof your home the air can be sucked right back into the attic from the soffit.
Surprisingly bathroom fans are not required by some building codes.
Bathroom exhaust fans perform an important function by removing excess moisture from your home.
Bathroom code does address the issue of moving odor and moisture laden air from the bathroom to the outside.
No you cannot vent the bathroom exhaust fan into the soffit vents.
If you vent through the roof condensation will drip back into the interior.
In all cases the ducting needs to conduct the exchaust to the building exterior and needs to terminate in an animal proof vent cover.
Bathroom ventilation codes require a bathroom exhaust fan to vent to the exterior not the attic for health and structural reasons.
The best exhaust fan venting is through smooth rigid ducts with taped joints and screwed to a special vent hood.
I recommend that my clients vent their bath fans out a gable wall if at all possible when not using an hrv or erv that is.
This involves running ductwork from the fan usually though an attic and out through the roof.
It eliminates the need for routing ductwork through the house and these fans usually dry the bathroom more quickly.
Depending on the location of the bathroom it may be easy to vent the exhaust fan through the roof.
Can you vent a bathroom exhaust fan into the soffit vents.
The lowdown on venting your bath fan into an attic is that it can be done but it should terminate on the outside.
I would by lying if i told you that it will cause problems it may be totally fine.
