What Size Should My Bathroom Ventilation Fan Be? 07/28/2017Everyday tasks like showering, bathing and shaving can put home-harming humidity into the air in your Great Falls home. There’s good news however—a modest bathroom ventilation fan can save you from distorted wood, mold growth, damaged drywall and other issues connected 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 noiseless and energy efficient as they could be? Falls Mechanical Services LLC is here to answer your questions. Today’s bathroom ventilation fans are small and sleek and they operate more quietly and economically 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 prevent warmed air from getting out through your ventilation. While you have a lot of bells and whistles to pick from, the most critical 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 transfer, a bathroom ventilation fan should be able to swap out the air in a bathroom at least eight times an hour. With a standard 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 higher 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 use HGTV’s advice for bathrooms larger than 100 square feet – verify 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 right size, or you know it’s the occasion for a new one, give the experts at Falls Mechanical Services LLC at call at 406-761-7283. We’re here to help you make sure you have a ventilation fan that will drive hard to care for your home and keep it comfy. You can even set up an appointment with us online if that’s easiest for you.