Why Bathroom Fan Makes Noise when Windy?


Does your house sound like a horror movie when it is windy outside? If the noise is coming from your bathroom fan I can help you stop the banging noise.

The bathroom fan makes noise when windy because the backdraft damper is picked up by the wind and then dropped down. This is what produces the banging noise.

How To stop a Bathroom Fan From Making Noise When Windy

Sometimes wind and roof vents don’t get along well. If you hear a banging or clanging noise coming through your bathroom fan when it’s windy, it is likely that the wind is picking up the vent flap and hitting it continuously with a banging noise.

These flapping noises come from the wind blowing from the other side of the house which pressurizes it on one side and depressurizes it on the side of the exhaust hood. With gusts of wind, that causes air to actually move from the house out through the exhaust duct. There are various remedies for the bathroom fan to stop flapping.

The sound can be even described as a clicking noise when the bathroom fan is turned off. This is common with low winds and aluminium dampers.

Here are some of the solutions which you can consider to stop your bathroom fan from flapping and hitting the metal when it’s windy.

Keep in mind that all of the solutions below will help eliminate range hood, dryer vent, and general ventilation system wind noise problems.

I have a separate article where I discuss why range hood makes noise when windy. Most of the info applies to both, but if you are having trouble with a noisy range hood, head out to the other article since there are a couple of nuances that are different for them,

Whenever a ventilation system makes flapping, banging, or rattling noises in the wind. Most likely the solutions here will help you.

Replace The Damper

The Best solution is to replace the existing damper with a spring-loaded butterfly backdraft damper.

If yours is making noise, then most likely you have one that works by gravity closing the flap and airflow from the fan opening it. This makes it very easy for the wind to pick it up and annoy you with the noise.

A spring loaded damper will open only when exhaust fan is turned on and is likely more airtight than your existing gravity damper. Many have rubber seals; against which the flaps close and create an airtight seal.

This requires attic access as you will have to remove the old damper from the air duct and install the new one. Make sure you order the right size as the air duct can vary from 4 to 8 inches.

I recommend AC infinity dampers (amazon link) because they use quality rubber seals to prevent noise and any air leaks. They have dampers from 4 to 8 inches to fit most applications.

Foam it up

This is one of the cheapest solutions to stop the fan to flap is by getting some soft foam and self-adhesive weather-stripping tape to tape the exhaust hood where the flapper hits the metal. In most cases, this will stop the noise.

This is the kind of foam I am talking about on amazon. Unfortunately, it is difficult to find small pieces for sale so you must buy an entire roll.

Weigh it down

Attach small washers with a tab of silicone to the flap, be careful not to weigh it down too much. The fan should still be able to easily push it open when turned on.

Another alternative is to use wheel weights. They have a waterproof adhesive backing and are very easy to install. Wheel weights from Amazon.

The additional weight of the washer or wheel weight will make it harder for the wind to move the flap up and down. Thus eliminating the noise.

Wind Blowing Through Extractor Fan

Nobody likes a cold draft. Not only is it uncomfortable, but it is also not energy efficient to have the wind blowing through your extractor fan.

It is supposed to work the other way around. It is called an extractor fan for a reason 🙂

You might have noticed that the problem is worst when you have some other fan turned on at the same time.

For example a range hood.

Since they tend to be very powerful they can even create a draft from a running fan. (Provided the house is airtight)

It is very easy to stop wind blowing through the extractor fan.

Simply fit a backdraft damper and you are good to go! Don’t buy the cheapest plastic damper you can find.

In-fact, this might be installed in your ventilation system right now and could be causing the daft in the first place.

Instead, get a quality spring-loaded damper with rubber seals. You can find the link to the damper I recommend if you scroll up.

What Are Bathroom Fans and What Do They Exactly Do?

Bathroom fans or most commonly known as vent fans or exhaust fans help in ventilation like moving the smoke, moisture, and bad odor out from the room. Bathroom fans are generally installed in or near the shower, or tub and the exhaust is usually placed opposite the air supply source to make sure that the fresh air is drawn through the room.

Related article: What are bathroom fans for

For ventilation purposes, the bathroom doors are not completely sealed i.e. there’s always a small gap in-between floor and door to allow fresh air to enter the room and pull out any unwanted airborne particles.

If there’s nowhere for steam to travel, it’ll condensate on the surface of the bathroom and might produce mildew, mold, and stinky odors. If left unattended, it can peel the bathroom wallpaper, rotting drywall, and even warp wood trim and furnishings. Read my article about preventing mold in the bathroom to learn more.

When to Use a Bathroom Fan?

Bathroom fans can be used anytime to freshen up the air. However, for best results, you should always run it during hot showers for about 20 minutes afterward, or until the steamed air is completely thrown out. From an energy-saving perspective, it’s also important to remember to turn off the fans when they’re no longer needed. Here you can learn more about bathroom fan energy usage.

What if it Makes Noise Without Wind?

There can be a lot of different reasons behind a noisy fan. Since I have previously written an article about why bathroom fans get noisy I won’t go into more detail here.

What is a Backdraft Damper for Exhaust Fan?

A backdraft damper is one of the few pieces required to help in the overall functioning of the ventilation system. It allows the contaminated air to efficiently flow out of the exhaust ducts and prevent the unwanted flow of air into the house when the exhaust fans are off.

Often used in bathroom vents and kitchen exhaust systems, backdraft dampers stop cold air from coming inside, allowing a more comfortable temperature in your home. Backdraft Dampers are built with blades that are designed to allow air to flow through in one direction out of the house while keeping cold air outside during the winters.

A back-draft damper is essential for an energy efficient home.

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Joonas Pütsepp

I like it when I'm able to fix everything that needs fixing around the house. In order to do that, I have to do a lot of research. This site will cover everything I learn and maybe help others do the same.

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