Exhaust Into Attic

Duct already wrapped in insulation at home centers.

Exhaust into attic.

This can be a serious problem in cold weather if the living space is not properly sealed off from the attic. Bathroom exhaust fans perform an important function by removing excess moisture from your home. Taking advantage of this natural process referred to as passive ventilation is the most common way to vent an 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.

Step 2 run the ducts. It may also violate a shingle warranty. All municipalities have different requirements but some do not draw a hard line on requiring exhaust fans. Surprisingly bathroom fans are not required by some building codes.

Bathroom code does address the issue of moving odor and moisture laden air from the bathroom to the outside. Your vent hood will have places available for either attic or wall exhaust. The reason you don t vent into the attic is because when the attic is colder than the vent air moisture will condense inside the attic space causing mold and other problems. Small diameter ducts could trap grease creating a fire hazard.

Hot air exhaust vents located at the peak of the roof allow hot air to escape. In either case do not vent into the wall or the attic. The duct for your exhaust fan needs to be run to the outside of the house to remove the chance of a fire hazard. The fan s installation instructions should specify the diameter of the duct.

The kitchen vent fan must exhaust directly to the outside not into an attic crawlspace or a space between floors. Options for venting a bathroom exhaust fan include best to worst. 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. After further inspection it was evident the current home owners vented their bathroom exhaust fans directly into the open attic space and not to the outside.

The duct should be smooth and straight with as few bends as possible. You can find 4 in. 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.