What Size Should My Bathroom Ventilation Fan Be?

July 28, 2017

Average tasks like showering, bathing and shaving can put home-harming humidity into the air in your Saint Petersburg home. There’s good news though—a straightforward bathroom ventilation fan can keep you from warped 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 quiet and energy efficient as they could be? Hale's Air Conditioning Services Inc is here to answer your questions.

Today’s bathroom ventilation fans are small and sleek and they run more quietly and economically than ever before. You’ll find a hefty range of options, 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 there are a lot of bells and whistles to choose from, the most imperative aspect of your fan is whether or not it’s large 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 at least 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 adequate.

If you have a larger 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 heed HGTV’s advice for bathrooms larger than 100 square feet – establish 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 the occasion for a new one, give the pros at Hale's Air Conditioning Services Inc at call at 727-369-6195. We’re here to help you make sure you have a ventilation fan that will work hard to guard your home and keep it cozy.