How to Install a Bathroom Exhaust Fan

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A bathroom exhaust fan serves two purposes. One it eliminates odors in the bathroom and second greatly reduces the moisture in the bathroom. By reducing moisture you will eliminate mold and mildew build up that causes the paint to peel off the walls and ceiling. You will also eliminate the bathroom door and cabinet doors from warping. So as you can see a bathroom exhaust fan can save you maintenance and repairs. Exhaust fans come in many different styles and models. You can get one that mounts on the wall or ceiling. Installing one will require some basic electrical work and making a cutout in the wall or ceiling.

Material and Tools :

Screwdriver set

Jig saw or Drywall hand saw

BX cable (shielded: 2-wire with ground wire)

Wire stripers

Lineman pliers

Wire nuts

Electrical tape


Exhaust fan

Flexible vent duct

Vent duct clamps


Shut off the electricity to the bathroom light switch. If you are replacing your bathroom light fixture with a ceiling exhaust fan with a built in light, you will need to remove your old light fixture and electrical box.

Step2 :

The exhaust fan should be mounted between two ceiling joist. If this is not possible install a wooden brace between the two joists for a secure attachment. You can use a 2 x 3 or 2 x 4 to construct the brace. Make the necessary cutout in the ceiling to accommodate the vent fan.


Mount the exhaust vent fan as detailed in step 2.and connect the flexible ducting to the fan housing.


If you are using the same light switch for the bathroom light, run your electrical cable from the light switch to the vent fan and make your connections. Be sure to connect the ground wire also. Use wire nuts to secure all electrical connections. Refer to the manufacture’s instructions for details. If you want to use a separate switch you will need to use 3 conductor BX cable for the hook up.


After your vent fan is mounted and wired, install the unit cover from inside the bathroom.


You will now need to run your flexible vent duct to the outside of your house. If your exhaust fan is in your attic, then route the duct to the nearest soffit. This allows you to make the vent installation under the overhang of the roof, preventing the need for a roof vent. Run the vent duct over the insulation that’s between the attic floor joist and out to the nearest soffit. Use a vent duct clamp to connect the duct to the soffit vent.


If you decided to use a wall vent, mount the vent on an outside wall. This will eliminate the need for any duct work.


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