Bathroom Exhaust Fan Vented Into Attic

The lowdown on venting your bath fan into an attic is that it can be done but it should terminate on the outside.

Bathroom exhaust fan vented into attic.

Bathroom exhaust fans perform an important function by removing excess moisture from your home. The truth about attic bathroom venting. 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. This article describes routing bath exhaust fan duct upwards through an attic or roof space or downwards through a floor or crawl space.

Never allow the duct to simply blow into an attic crawlspace or other enclosed area. Bathroom ventilation fan duct routing routing a bath vent duct down out or up through an attic or roof out. You d often blow air from one bathroom into the other and local building inspectors wouldn t approve it. Bathroom fan vent code requirements include no venting to attic areas to help reduce mold or structural problems.

Note that the bathroom vent fan must always exhaust to the outdoors. In fact i have seen numerous houses that haven t yet had signs of mold with the bath fan venting incorrectly. Bathroom ventilation codes require a bathroom exhaust fan to vent to the exterior not the attic for health and structural reasons. No you cannot vent the bathroom exhaust fan into the soffit vents.

In all cases the ducting needs to conduct the exchaust to the building exterior and needs to terminate in an animal proof vent cover. But while you can t have two fans with one vent you can make one fan and one vent serve two bathrooms. This setup requires an in line centrifugal fan mounted in the attic drawing air simultaneously from both bathrooms see photo. 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.