What Size Should My Bathroom Ventilation Fan Be?

July 28, 2017

Everyday tasks like showering, bathing and shaving can put home-harming humidity into the air in your the Bay Area home. There’s good news however—a straightforward bathroom ventilation fan can protect 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 proper size? Are they as quiet and energy efficient as they could be? Contra Costa Heating & AC is here to answer your questions.

Today’s bathroom ventilation fans are small and modern and they operate more quietly and efficiently than ever before. You’ll find a hefty range of selections, from simple fans that will get the job done to fans with integrated heat lamps, motion sensors and heat-exchanger ventilation that helps avoid warmed air from leaking through your ventilation. While there are a lot of bells and whistles to select 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 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 about 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 sufficient.

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 straightforward, you can use 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 unsure if your bathroom ventilation fan is the correct size, or you know it’s come to the point for a new one, give the experts at Contra Costa Heating & AC at call at 510-343-9841. We’re here to help you make sure you have a ventilation fan that will run hard to care for your home and keep it comfy.