Choosing a Bathroom Fan

Scott Gibson, Contributing Editor

Can you recommend a quiet ceiling exhaust fan for a 4 ft. by 8 ft. bathroom? Our house is a ranch built in 1960. There is an awning window in the bath.

You have a number of choices when it comes to a bathroom fan that won't drive you crazy. Manufacturers have made great strides in getting the noise level down to the point where fans are nearly inaudible. That's the key to using a fan regularly. As important as ventilation is to controlling moisture, it's hard to blame anyone for not using a fan that makes a terrible racket every time it's turned on.

Sound is measured in 'sones.' The amount of noise a bath fan generates is measured in "sones," a scale unlike the more familiar decibel. One difference is that the sone scale is linear, meaning that doubling the number corresponds to a doubling of perceived loudness. As a result, it's easier to compare fans when you shop and make a reasonable guess about how much noise it's going to make when it's in the ceiling.

One sone is about as much noise as a quiet refrigerator makes in a quiet room. Four sones is about as much noise as your TV makes from three feet away-- assuming you have the volume set at what most people would consider "normal."

At least two companies make bathroom fans that are rated at less than 1 sone. Both Panasonic and Broan-NuTone offer models rated at about one-third of a sone, quiet enough that you may forget you've turned them on. These small capacity fans don't have the capacity to clear out some of the mega-bathrooms that are being built these days. But with a bathroom that measures only 32 square feet, you could safely go with a small (and very quiet) model.

For bathrooms up to 100 square feet, the Home Ventilation Institute ( recommends one cubic foot of exhaust air per minute for each square foot of floor area. In your case, you'd only need a fan rated at 32 CFM. That's enough air movement for the recommended eight air changes per hour.

A 50 CFM Panasonic would be an excellent choice. It draws only 13 watts, produces less than one-third of a sone and has a built in damper to keep cold air out of the house. You can buy one for about $80. It's even Energy Star rated.

Get more than a basic model. You might consider the 1960s the dark ages of home ventilation awareness. Lots of houses from that era were built without any mechanical ventilation whatsoever.

When you upgrade with a new fan, you can choose a model that can run continuously at a low setting to move a little bit of air all the time, then jump to a "boost" mode when you take a shower.

Or check the wealth of controls that are available: sensors that turn on the fan when the humidity level reaches a certain set point, timers that turn the fan on and off at prescribed times of the day, switches that turn the fan on automatically when you walk into the room. (For a sampling, visit

Of course you're still going to have to install the fan, and that can be a chore. But some small fans are designed for installation in an existing bath. They use small-diameter ducts and are flat enough to go into ceilings with 2x6 joists.

You'll be happy you went to the trouble. And so will your house.

About the Author
An accomplished woodworker and carpenter, Scott Gibson is the former editor of Fine Woodworking magazine, and a former editor at Today's Homeowner and Fine Homebuilding magazines. He also is former managing editor of the Kennebec Journal, a daily newspaper in Maine.

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