What Size Should My Bathroom Ventilation Fan Be?

Ordinary tasks like showering, bathing and shaving can put home-destructive humidity into the air in your Des Moines home. There’s good news however—a modest bathroom ventilation fan can keep 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 correct size? Are they as soft and energy efficient as they could be? Kohles & Bach Heating & Cooling 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 hefty range of options, from classic fans that will get the job done to fans with integrated heat lamps, motion sensors and heat-exchanger ventilation that helps block warmed air from escaping through your ventilation. While you can find a lot of bells and whistles to pick from, the most imperative characteristic of your fan is whether or not it’s big enough to do its job.

Assessed by the cubic feet per minute (CFM) of air they move, a bathroom ventilation fan should be able to replace the air in a bathroom at least eight times an hour. With a typical 8-foot ceiling, your ventilation fan should have a CFM rating about the number of square feet in your bathroom. Therefore, 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 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 heed HGTV’s advice for bathrooms larger than 100 square feet – determine your CFM requirements by adding 50 CFM for every toilet; 50 CFM for each shower, bath and combo; and 100 CFM for each whirlpool.

If you’re unsure if your bathroom ventilation fan is the proper size, or you know it’s come to the point for a new one, give the experts at Kohles & Bach Heating & Cooling at call at 515-207-6569. We’re here to help you make sure you have a ventilation fan that will work hard to protect your home and keep it comfortable. 

Back To Blog