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Install a Bathroom Exhaust Fan

A foggy bathroom after every shower means your exhaust fan isn’t doing its job. That excess moisture in the air can lead to a big problem—mold. A new exhaust fan will clear the steam and help prevent mold. The installation takes only a few hours to complete.

Tools & Materials

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Buying a New Bath Fan

When you’re picking out a new fan pay attention to CFMs and sones. Sones indicate how loud a bath fan is—the higher the number the louder the fan. 2 sones is considered quiet.

CFM stands for cubic feet per minute. It’s the measurement of airflow. The larger the room, the higher the CFM number you’ll need.

It’s best to get a fan that’s rated for the size of your bathroom. Here are a few CFM recommendations:

Powder room: 50 to 60 CFM

Medium-size bathroom: 70 to 90 CFM

Large master bath: 100+ CFM

Also note the size of your old fan. The easiest replacement is to get a new fan that’s the same size as the old one. You can take your old fan to the store to check.

Remove the Old Bath Fan

Step 1

Cover the work area with a drop cloth. Turn off the power to the fan. Take off the cover and use a circuit tester to doublecheck that the power is off.

Step 2

Remove the motor.

Step 3

Take out the mounting screws. Some may have to be removed from the attic.

Step 4

Slide the housing to the side and disconnect the vent duct.

Step 5

Pull down the housing and label the wires. Then disconnect the wires.

Install a Larger Fan

Step 1

Hold the new fan housing up to the ceiling and mark it.

Step 2

Cut the hole with a drywall knife.

Install a Smaller Fan

Step 1

To make the hole in the ceiling smaller you’ll need to patch it with a piece of drywall. Determine the size of the hole you’ll need and cut a piece of drywall to fit. Also cut a 1-by-2 just a little longer than the hole opening.

Step 2

Attach the drywall piece to the 1-by-2 with screws. Slide it into place and secure it in the hole with drywall screws.

Step 3

Apply joint compound over the seams and let it dry. Sand it smooth, then apply a little more joint compound. Sand one more time and finish up with primer and paint.

Install the Fan

Step 1

Some fans require setting the duct connector in the ceiling first. Hold the housing up, lining up the connector with the slots, and slide the housing into the hole.

Step 2

If you don’t have an attic or access to your attic, check your manufacturer’s instructions for recommendations. Typically, you would need to frame part of the hole. Cut a 2-by-4 to fit between the ceiling joists and secure with screws. Remember to keep the vent side clear.

Step 3

Keeping the housing level and square with the joists, drive screws through the mounting holes into the joists.

Step 4

The next few steps should be completed in the attic. Skip this step if you added extra 2-by-4 bracing between the joists.

From the attic, set a board to kneel on near the fan. Attach the brackets to the joists. Then connect the brackets to the fan body with screws.

Step 5

Attach the ducts to the connector with HVAC tape.

Step 6

Hook up the wiring by first removing the junction box cover. Then connect the house wires to the fan wires: ground to ground, neutral white to neutral white, and hot black to hot black.

Step 7

Replace the junction box cover and turn on the power. If the fan sounds loud like something isn’t right, turn off the power and check that it’s mounted securely and level.

If it sounds ok, add the mounting springs and push the cover into place.

Cleaning Your Bathroom Fan

Step 1

Turn off the power to the fan and remove the cover.

Step 2

Wash the grill in the sink, and dry it with a cloth.

Step 3

Use a vacuum cleaner to remove dirt and dust from the fan body.

Step 4

Clean the fan body with a damp cloth, then wipe it with a dry cloth.

Step 5

Replace the cover and turn on the power.