How to Fix a Noisy Bathroom Fan: Complete DIY Tips from Experts


Your bath fan is likely louder than it should be if it’s older than 20 years. While a noisy fan can help mask noises in the bathroom, the jet engine roar can be pretty annoying. Even worse, your bath fan might not be moving enough air for your bathroom to remain free from mold and mildew.
Are you looking to know how to fix a noisy bathroom fan? Although there are many reasons why noisy bath fans may occur, it is usually just one.

How to fix a noisy bathroom fan

A loud bathroom fan is one of the most frequent complaints from new homeowners. These fans are louder than others, especially those of lower quality and ‘builder-grade’ quality. They also get louder with age. Bathroom fans can become noisy as they age. The motor can lose its lubrication, the fan blades may be misaligned, the grille could get clogged with dirt, and the duct can block airflow.

Dirty grille cover

A dirty or clogged grille cover is one of my most frequent issues as a home inspector. Dirty bathroom fans can become a fire hazard if the fan motor gets too hot. The bathroom fan grille is usually the most visible part of the bathroom fan. These grilles are generally white or beige and can quickly get clogged up with dirt and other debris. Most homeowners don’t clean their bathroom fan grilles. A dirty grille can cause a fan to be very loud. Bathroom fans can make strange noises if they don’t get enough air.

Dried out motor bearings

Oil wick bearings on older bathroom fans may need to be lubricated periodically with light engine oil. Oiling the fan motor is similar to cleaning the grille cover. These bearings help to keep the motor running smoothly. If they’re not maintained with oil, the “wicks” will dry and cause the motor’s roughness. An engine that isn’t well-oiled can make much more noise than one. Recently, I oiled an old Broan bathroom fan. It made a huge difference in its sound quality and made it run more efficiently. To add oil to these wick bearings, you will need the bathroom fan motor removed. The bearing brackets then need to be taken out. A few drops of oil in each part will be enough. Almost any engine oil should suffice.

Fan blade misalignment

It’s a good idea to remove the fan motor from the fan motor to oil it. Also, make sure the fan blades are correctly spinning. If one of the fan blades hits something or is wobbly as it spins, that can cause much more noise when running. You can spin the fan blades using your finger to check if there is anything odd about how they turn. If the fan blades are not spinning in a smooth and balanced manner, it may be time to replace them or buy a new bathroom fan.

Too many duct bends

Too many duct bends can also cause noise. More duct bends will result in more noise. A bathroom fan duct should be 3 to 5 degrees in diameter, with no sharp 90-degree turns. To maximize airflow (and reduce noise), duct bends should be smooth and gradual.
You can also use rigid metal ducting instead of flex ducts to reduce noise. Flex ducts ‘ ridges catch air and create resistance. This can increase the noise level.

Clogged duct

It is widespread for birds to build nests in dryer vent ducts and bathroom vent ducts. The bird’s nest can stop the airflow completely, so your bathroom fan will not work well. A bathroom exhaust fan can be affected by the noise the blocked or nearly stopped airflow makes. Turn on the bathroom fan to check for airflow. Next, restrict the outside airflow. The bathroom fan vent cover flapper should be able to open when the fan is turned on. If the flapper doesn’t move (or isn’t fully open), there is most likely no air coming out. A stuck flapper could also be a problem. You may need to use a ladder to inspect the bathroom fan vent for airflow if it is high.

Too small a duct

Bathroom fans with modern designs require a larger vent duct than the 3-inch standard. Many quieter bathroom fans require a duct width of 4 to 6 inches for proper operation. The performance metrics of your bathroom fan will not be as good as advertised, and you may hear it a lot louder than the manufacturer claims.

Get a new bathroom fan

Sometimes, the best solution is to purchase a new low-profile bathroom exhaust fan. Using’sones rate bathroom fan noise’, a measure of the noise level that humans perceive. Double the number of sounds will result in a doubled perception of loudness. A bathroom fan with 3-4 sones or more is considered loud.

The right size bathroom for you

There is no one-size-fits-all bath fan. Bathrooms up to 100 square feet. Calculate the cubic feet per minute required (cfm). This is done by multiplying the room’s length x width and height. Multiply this result by.13 to get the closest 10. Ex: 10 feet wide, 9 feet long, 9 feet high and 13 divided by 9 = 105. Round to 110 and get a 110cfm bath fan. Bathrooms larger than 100 square feet will need a 110-cfm bath fan. Add the following plumbing fixtures to your bathroom: toilet, 50 cm; shower, 50 cm; bathtub, 50 cm; and jetted tub, 100 cm.

Why is my bathroom fan so loud

It is good to be informed. Let’s begin with some background information about noise. The American National Standards Institute has created a unit for measuring noise in “phons”. A “sone system” is used to rate appliance noise. We’ll explain the relationship between phon and sone. It’s a simple and user-friendly system. 40-phons equal 1sone.

The quieter an appliance is, the smaller its sone number. For example, a refrigerator is approximately 2-sones. Bathroom ceiling fans give a rating of 1.5 to 5 stars. This means you can reduce noise when purchasing the bathroom fan. The fan will be quieter if it has smaller sound output. A very quiet bathroom fan might not exhaust the air. A low sound level is essential to ensure the fan is soft but also to ensure that the fan moves the air. If it doesn’t, then what’s the point in having a fan? This is where “CFM” comes in.


Homeowners can find it annoying to hear and see the bathroom fan noises. There are often simple solutions. First, clean the grill if it is dirty, and then oil the fan motor. If oiling and cleaning don’t work, I will inspect the duct to ensure proper airflow. If all else fails, you might need a bathroom fan with a 1.0 sone rating or less. This will make it super quiet. We hope now you understand how to fix a noisy bathroom fan.

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