Homeowner Guide to Bathroom Exhaust Fans

Homeowner Guide to Bathroom Exhaust Fans

Humidity is a never-ending problem in South Florida, and September is the worst month of all with an average of 78 percent. One way to reduce the moisture in your indoor air is by making sure your bathroom exhaust fan is effective at venting humidity to the outside.


If you’re not sure if it’s doing the job, it might be time to replace it. An upgraded model with all the bells and whistles will provide superior performance at an affordable price.

The Purpose of Bathroom Exhaust Fans

Along with removing unpleasant odors, your exhaust fan removes moisture from the air. This prevents excess humidity from the bathroom infiltrating the rest of your home.

Excess humidity can result in damage to your home’s fixtures and finishes. It can also cause health problems, such as asthma and sinusitis. These two factors alone make it worth replacing your fan with a more efficient model.

Sizing Your Bath Fan

The “size” of your bathroom exhaust fan refers to how much air it can move. This is expressed as “cfm” — or cubic feet per minute. By determining the size of your bathroom and calculating how much air needs to be removed for good ventilation, you can see what size exhaust fan you need.

Luckily, you’ll find this in a handy reference chart provided by experts in the industry, like the Home Ventilation Institute.

Bathroom Size Fan Size

<50 square feet 50 CFM

50 to 100 square feet 1 CFM per square foot

>100 square feet 50 CFM for each bath fixture, plus another 50 CFM if you have a jetted tub.

Using the recommended size bath fan will deliver eight complete air changes in the room every hour.

Unless you’ve remodeled and changed the size of your bathroom, it probably has the right size fan already. But, if you’ve upgraded to a jetted bathtub or added in a new bidet, you may need to upgrade the fan too.

Walled-off water closets also need their own exhaust fan.

The Best Features in a Bathroom Exhaust Fan

You may be surprised to find some extra features appearing in even the modest bathrooms lately. Exhaust fans are no exception.

Once you have a budget in mind, you may want to look for some of these upgrades:

1. Lights

Lighted bath fans are a boon for parents of small children. They’re handy for grownups, as well. Most models offer enough light to make sure you can finish your business without incident. Some offer both room lighting and night lighting.

2. Heater

It doesn’t get really cold in South Florida, but a few nights will leave a chill on the tiles. Bathroom exhaust fans with heaters warm up just the bathroom, so you don’t have to turn on the furnace to bathe comfortably.

3. Humidity sensor

Not everyone can remember to turn on the fan before showering. And more often, they forget to turn it off. Humidity sensors will operate your exhaust fan automatically, so you don’t have to sweat the small stuff.

4. Motion sensor

Motion sensors in restroom fans have been a staple in commercial construction for decades. Now, you can find them for residential use. Many will automatically provide light and ventilation whenever motion is detected in the room.

4. Bluetooth

If singing in the shower is your path to happiness, then a bath fan with a Bluetooth speaker might be just the thing. There’s no need to stop the music just because it’s bath time!

Important Bath Fan Specs

Along with featuring some luxuries, you should expect any bathroom exhaust fan to meet basic operational specifications.

Sound levels

Many homeowners find bathroom fans noisy. This can alert your entire household to your personal business and interfere with your relaxing bath. Especially if you can’t hear what your 6-year-old is shouting from the other side of the door.

Bath fan sound levels are measured in sones, not decibels like other appliances. You’ll find them listed from as low as 0,3 sones up to 4 sones. A sone level of 4 is equivalent to watching a TV in the bathroom, which is pretty loud for such a small room. The smaller the sone rating, the quieter your fan.

Sizing, part 2

Along being sized properly for performance, any new bath exhaust fan needs to be sized correctly for the existing duct and cutout. Make sure you measure the hole in the ceiling and the size of the vent to outside carefully (even twice) before buying a new fan.

If you’re not sure how to install your new bath fan, make an appointment today with the technicians at One Hour Air in Miami. We’ll install it for you and have it working to expectations in no time.