What Size Should My Bathroom Ventilation Fan Be?

Ordinary tasks like showering, bathing and shaving can put home-harming humidity into the air in your Tucson home. There’s good news however—a straightforward bathroom ventilation fan can save you from distorted wood, mold growth, broken drywall and other issues 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? Ambient Air is here to answer your questions.

Today’s bathroom ventilation fans are small and sleek and they operate more quietly and efficiently than ever before. You’ll find a large range of selections, from classic 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 getting out through your ventilation. While you have a lot of bells and whistles to select from, the most imperative feature 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 move, a bathroom ventilation fan should be able to replace 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. Therefore, 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 simple, you can follow HGTV’s guidance for bathrooms larger than 100 square feet – verify 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 not sure if your bathroom ventilation fan is the correct size, or you know it’s the occasion for a new one, give the pros at Ambient Air at call at 520-201-3871. We’re here to help you make sure you have a ventilation fan that will work hard to guard your home and keep it comfy. 

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