Your Bathroom Fan Should be Vented

Every bathroom should have a fan. The building code requires that the fan vents directly to the exterior. Even if the attic space is vented, the fan must vent to the exterior to prevent moisture accumulation. This is how you can vent your fan.

Installed soffit vents that duct bathroom fans to the exterior.

The fans can vent through the wall, roof, or soffit. Venting through the soffit limits roof penetrations and avoids putting a hole in a brick wall, which was the case in this instance.

For the fan install, remove the existing light. This new unit is a dual fan and light unit. First confirm the electricity is off. Even if the unit is on a switch and the switch is off, the circuit breaker should still be off. Measure the new fan and marked the location in the attic. The existing light was centered in the room, so the new unit was placed in the same spot. The opening was enlarged for the fan with a hack saw. Since there is not an adjacent joist, a 2x4 across joists is installed to mount the new fan. Once the fan is mounted, connect the wiring using wire nuts and confirm the light and fan work. Installation instructions should be provided with the unit.

Soffit vents.

Now, the fan must be vented. While there is already a fan in the other bathroom, it is not vented to the exterior. Instead it emptied into the attic space. That is not right and violates building code. The correction is easy.

Purchase 4" flex duct from a home supply store. Confirm that the fan has a 4" outlet. This is a standard size. A clamp ring will attach one end of the duct to the fan.

Flex duct, 4".

Clamp ring.

The duct will run to the soffit. If access to the soffit is difficult, push the duct into the soffit as far as possible.

Ducting running to the soffit in the attic.

Measure the proposed vent locations from the inside by locating a reference point. The bathroom waste line vent is a good reference. Transfer those measurement to the outside using a piece of tape on the gutter to mark the location. For this install the measurements were 36" and 60" from the waste vent.

Using a ladder to reach the soffit, mark the opening with the provided template (which was too small), and cut out the soffit with a jig saw. A pilot hole for the jig saw will need to be drilled first. When installing two vents simultaneously, confirm that the vents are spaced equally from the house for a professional look.

Holes cut and ready for the vents.

The kit provides the vent and screws. Pull the end of the duct through the opening and attach it to the vent.  If the neck isn't long enough for a clamp ring, use foil tape. Confirm a good seal between the duct and vent.

Push the vent into the opening, and use the vent as a template to drill the mounting holes. Screw in the vent with the provided screws to complete installation.

The vent has a spring attached to the damper. When the bathroom fan is switched on, the damper opens. Now, the fans vent to the exterior, meet code, and prevent moisture accumulation in the attic space. If you're buying a house, confirm the bathroom fans are vented, otherwise you may end up doing it yourself later.