What Size Should My Bathroom Ventilation Fan Be?

Everyday tasks like showering, bathing and shaving can put home-destructive humidity into the air in your Rapid City home. There’s good news still—a simple bathroom ventilation fan can keep you from warped wood, mold growth, cracked drywall and other problems connected with a humid bathroom.

Even if you have ventilation fans in your bathrooms, do you know if they’re the proper size? Are they as noiseless and energy efficient as they could be? Street Heating and Cooling is here to answer your questions.

Today’s bathroom ventilation fans are small and sleek and they run more quietly and efficiently than ever before. You’ll find a hefty range of selections, from average 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 big 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 exchange 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 about the number of square feet in your bathroom. So, if your bathroom is 5 feet by 8 feet, a CFM rating of 40 would be adequate.

If you have a taller ceiling, the equation gets a little more complicated. 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 follow HGTV’s advice for bathrooms larger than 100 square feet – verify your CFM requirements by increasing 50 CFM for every toilet; 50 CFM for each shower, bath and combo; and 100 CFM for each whirlpool.

If you’re not sure if your bathroom ventilation fan is the proper size, or you know it’s the occasion for a new one, give the pros at Street Heating and Cooling at call at 605-206-3915. We’re here to help you guarantee you have a ventilation fan that will drive hard to care for your home and keep it cozy. 

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