What Size Should My Bathroom Ventilation Fan Be?

July 28, 2017

Ordinary tasks like showering, bathing and shaving can put home-damaging humidity into the air in your Rapid City home. There’s good news though—a straightforward bathroom ventilation fan can save you from deformed wood, mold growth, broken drywall and other trouble associated with a humid bathroom.

Even if you have ventilation fans in your bathrooms, do you know if they’re the right size? Are they as quiet and energy efficient as they could be? Precision Mechanical is here to answer your questions.

Today’s bathroom ventilation fans are small and modern and they work more quietly and efficiently than ever before. You’ll find a great range of selections, from classic fans that will get the job done to fans with integrated heat lamps, motion sensors and heat-exchanger ventilation that helps prevent warmed air from escaping through your ventilation. While you have a lot of bells and whistles to select from, the most critical aspect of your fan is whether or not it’s full-sized enough to do its job.

Rated by the cubic feet per minute (CFM) of air they push, a bathroom ventilation fan should be able to swap out the air in a bathroom at least eight times an hour. With a normal 8-foot ceiling, your ventilation fan should have a CFM rating almost as high as the number of square feet in your bathroom. Thus, if your bathroom is 5 feet by 8 feet, a CFM rating of 40 would be satisfactory.

If you have a taller ceiling, the equation gets a little more difficult. You’ll want to multiply the width of the room by its height and length, divide it by 60 and multiply by 8. Or, to keep it easy, you can use HGTV’s advice for bathrooms larger than 100 square feet – determine your CFM requirements by toting 50 CFM for every toilet; 50 CFM for each shower, bath and combo; and 100 CFM for each whirlpool.

If you’re unclear if your bathroom ventilation fan is the correct size, or you know it’s time for a new one, give the pros at Precision Mechanical at call at 605-206-3766. We’re here to help you guarantee you have a ventilation fan that will run hard to care for your home and keep it comfortable.