Bathroom Echaust Duct In Attic

You should never exhaust the bathroom fan directly into the attic.

Bathroom echaust duct in attic. 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. Dumping bathroom exhaust into an attic or under roof space invites costly mold contamination frost under the roof in freezing climates moisture damage to roof sheathing possibly even plywood delamination or rot roof failures and shorter roof shingle life. Our photo above shows a long routing of bath vent fan ducts across an attic floor to an exit at the building soffit or eaves and the condensation of moisture in such vent lines. It may also violate a shingle warranty.

No you cannot vent your bathroom exhaust fan into the attic. If you re not comfortable working on a ladder call a professional for help. Your attic is not a temperature controlled environment is never the same temperature as your living space and generally closer to the temperature outside. When bathroom exhaust ducts are not properly insulated and vented the warm moist air traveling through them hits the colder section of the duct in the unconditioned attic space causing condensation on the duct work.

That condensation drips from the duct work in the attic space and the exhaust fan. An insulated duct will help prevent condensation when the warm air from the bathroom meets the cold duct in the attic.