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Properly installed bathroom exhaust fans act like climate control centers in what is the most complex climatic room in the house.

Bathrooms have standing water and evaporation makes these small rooms humid. Add in a shower or tub and the humidity in your bathroom has tropical density every time you use the shower. It is the job of a bathroom exhaust fan to regulate the humidity (moisture) and to help control odors - naturally occurring and man-made. They also help by getting rid of mold before it starts growing. Bathroom exhaust fans should be part of every bathroom remodel. 


discount bath remodel headquartersThe Technical Side of Bathroom Exhaust Fans

Technically, bathroom exhaust fans work shuttling the humid and odiferous air inside of a bathroom to the outside of your home. They do so by using a reverse fan that sucks air up through a vent system instead of blowing air around as a household fan does. By lifting humid air up and out, the fan creates a vacuum-like effect. If your bathroom fan is not properly vented, then that vacuum just sucks air from another part of your home or from your attic. Properly installed exhaust fans are vented to a soffit vent which draws fresh air from outside, not from the attic. 

In short, a bathroom exhaust fan has three basic parts. Those are:

  • The fan and motor
  • The expulsion vent - shuttles air outside
  • The intake vent - often a soffit vent that brings fresh air from outside the home.


Buying a Bathroom Exhaust Fan

The trick is to know the square footage of your bathroom. Exhaust fans are rated by the size of their motors. Bigger motors draw more air and service larger bathrooms. Smaller motors draw less air and service smaller bathroom. You can begin to see what happens if you install a small-motor fan into a large bathroom — the air exchange is very poor and you end up with all of the problems of a bathroom without an exhaust fan. Exhaust fans are rated by cubic feet per minute (CFM) which is why you need to know the square footage of your bathroom. 

What is the Proper Way to Install a Bathroom Exhaust Fan?  

This is really a big question. You need to decide how the fan will be wired, what type of fan you need, and how you will vent the fan. 

Wiring - How the fan is wired in will also limit your choices on what type of fan to buy. There are two wiring choices here - direct wiring which means the fan works on its own power source. Choice number two - wired to the bathroom light's switch which means when the light is on the fan is on. Many bathrooms have a separate switch for the fan and light. A few use a single switch for both. There is almost no conceivable benefit to wiring the fan to the light. The exception would be if there is not enough room for a second toggle switch at the light switch's location. If this is the case, consider moving the light switch during your bathroom remodel. 

Venting - Fans have to be vented otherwise you are just dumping wet air into a crawl space or into the attic. You will run across exhaust fans that are not vented correctly. Most will draw "fresh" air directly from the attic. All that is doing is redistributing dust and grime into the air you breath. The proper way to fresh-vent an exhaust fan is to use a soffit vent that vents from under the eaves of the roof at the low point. You always want fresh outside air. 


Bathroom remodel ideas for small bathroomsWhat Are the Benefits of Installing a Bathroom Exhaust Fan?

Properly installed bathroom exhaust fans help to regulate humidity throughout your home. They also help to prevent mold and mildew from forming. If you can prevent mold and mildew then you have solved much of the problem of getting rid of mold. Mold is not something that you just wipe away. It grows into its food source, which in this case are your walls, grout, and trim. Mold needs a warm and damp environment to live and a bathroom without a proper exhaust fan is just the ideal place.

Beyond mold and mildew, bathroom fans help keep the woodwork in your bathroom looking nice. Wet air causes the finish on metal and wood to deteriorate quickly. Nice wood becomes pitted, metal rusts, and the walls begin to look grungy. A bathroom exhaust fan helps to keep your woodwork looking nice, your walls cleaner, and your metal free of rust and pitting. 

Bathroom exhaust fans are important. They can also be a DIY project if you have electrical skills. You've got this. Just understand the type of fan that is needed for your bathroom, the way it needs to be wired in, and the size of your bathroom. From there you can choose the perfect exhaust fan and complete your bathroom remodel like a pro. 



David S. loves to tell stories. He came from a fishing family so storytelling is likely genetic. His writing style translates easily to both blog and article formats. He is a patient writer who takes the time to understand your project. David writes a great deal about home living. His favorite place in the world is his home. He has a vast knowledge of antiques, art, and deep love of cooking. He likes to entertain and is the master of small parties and intimate dinners. They say home is where the heart is and they happen to be correct.