Duct Exhaust Fan 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.

Duct exhaust fan in attic.

Options for venting a bathroom exhaust fan include best to worst. Terminating the duct in the attic is surprisingly common and harmful. A bath vent fan duct that is too long may restrict air flow such that the fan is not functional. You can find 4 in.

Here we provide specifications for recommended minimum maximum duct lengths for bathroom vent fans. Avoid venting through a soffit vent or ridge vent. The warm air will exhaust out the duct and enter back into the attic through the soffit vent or ridge vent. An external thermostat mounted in the attic controls the temperature and kicks the fan on when the temperature raises to the set limit.

The exhaust duct should be connected to the fan box with mechanical fasteners metal tape and or mastic and not regular cloth backed duct tape. Consider this a wake up call and extend the duct to vent the air outside before major damage occurs. A 3 or 4 inch duct connects to the outlet on the fan housing and runs to a side wall or to the roof and connects to a vent cap that allows the. Letting the fan exhaust into an open attic will cause moisture buildup on the underside of the roof.

Bathroom exhaust fan duct length specifications. Moist air will condense on framing and sheathing forming ice or water that will support rot and mold or damage the rooms below. Bathroom exhaust fans perform an important function by removing excess moisture from your home. Venting the kitchen vent fan must exhaust directly to the outside not into an attic crawlspace or a space between floors.

A bath vent fan duct that is too short may violate the manufacturer s installation instructions may not work properly or may be drafty. Although this isn t always possible in attic crawl spaces you should always insulate the duct to prevent condensation problems. Fan is vented into the attic. In order for attic exhaust fan to be effective you need a supply of fresh air coming in from soffits under the roof s overhang or gable vents.

The best exhaust fan venting is through smooth rigid ducts with taped joints and screwed to a special vent hood. If you have access to the attic the fan can vent either through a gable wall or roof.