Install a Bathroom Exhaust Fan

A luxury bathroom with his and hers sinks.
What You'll Need
Exhaust duct kit
Jab saw
Wire stripper
Wire nuts
Electrical tester

Every time you run hot water, you create steam. That steam penetrates every crevice and soon cools down and turns to water. When this happens in an area that doesn't dry efficiently, you create a prime breeding ground for mold spores. The key to preventing mold and mildew growth is to get the moist air out of the bathroom before it has a chance to condense, and an exhaust fan is the best way to do this.

A small exhaust fan, typically mounted in the ceiling, pulls the moist air right out of the bathroom and sends it up an exhaust pipe. There are a wide range of fans available for you to choose from. Whether you are installing one for the first time or replacing an inefficient one, it will make a major difference in the battle against mold.

Exhaust Fan Types and Quality

There are several different styles of exhaust fans, as well as levels of quality. The first choice that you need to make is whether or not you want a light integrated into your unit. This requires a little bit more electrical expertise during the installation stage, but an integrated unit adds a fan without having to create two separate openings in your ceiling to house both fixtures.

There are two measuring factors that determine quality. The amount of air the fan moves is measured in CFM (cubic feet per minute). Higher quality fans will move more air than a lower quality one. The other measure is how loud the unit is. Most manufacturers put a noise rating right on the package. The quieter the unit, the higher the quality.

Step 1 - Open the Ceiling

Ideally, your new exhaust fan will be mounted right over the hole in your ceiling where the light is. In the rare instance that you don't have an overhead light in your bathroom, you’ll need to create an opening. Use the duct kit you purchased to determine how big the hole should be first. The plasterboard ceiling can be cut with a jab saw. The cut doesn't have to perfect since the outside housing of the fan will cover any minor mistakes, but you still want to be fairly accurate so that you don't lose any insulation value around the outside of the duct pipe.

Step 2 - Wire the Fan

The wiring in every house is a little bit different. If your bathroom light is already wired into a wall switch, then that is the best place for you to wire your fan. Since every situation is going to be unique, I would recommend buying a book on electrical work. It will sketch out the many different options and types of switches and how each one should be wired. With different colors and varying sizes of wire, it's best to have it all laid out clearly in front of you.

Step 3 - Install the Duct Kit

Mount the box that your fan will hang on right above the hole. This box can be attached directly to the joist or, if the hole is too far from the joist, you can use the special hanger that comes with the kit. This hanger consists of a steel bar that rests across the joists and allows the box to slide back and forth. That way you can locate it directly over the hole. After the fan is positioned, attach the length of duct hose onto the mounting bracket.

Step 4 - Vent to the Outside

Once the hose is run up into the attic, find your way to the closest roof soffit. Cut a hole into the soffit according to the instructions that came with your kit, and attach the hose to the vent that mounts on the outside. This vent should also be included in your kit. Since the soffit faces down, you don't have to worry about rain, snow, or other debris getting into the exhaust pipe, and the moist air from your bathroom will be safely pumped outside.