Cold Air Coming in Through the Bathroom Exhaust Fan? (What To Do)

Updated on July 21, 2022

Do you have an issue with the air coming in through your bathroom vent fan? No problem, there are several solutions available to you to stop cold air coming into your bathroom fans.

Ensuring that your attic, doors, vents, ducts, and exhaust pipe are properly insulated will keep cold air infiltration from entering your bath. You can accomplish this with metal tape, insulation, dampers, and some flex duct.

Related: How to Replace a Bathroom Fan Without Attic Access

Materials Available to Insulate Bathroom Exhaust Fans

When you need to insulate an exhaust vent or some clothes dryer vents to prevent air from entering into your bathroom vents, it’s important to know some of the options available.


For those smalls cracks and gaps between the walls and ducts, consider using a caulk gun to seal them off. It’s a cheap and simple solution that’s easy to undo in the event of a remodel or repair.

Flex Duct

If you need to upgrade your bathroom ductwork, then consider investing in some flex duct. It’s a great option for an exhaust duct that is already insulated by design, so it’ll save you money without the extra hassle of an added step.


There are several types of insulation available to prevent air from entering through your roof vent and ceiling exhaust fan.

You can buy fiberglass wrap insulation for your ventilation ducts, walls, or attic, or you can buy foam board insulation for the walls or attic of your home.

Properly insulating your home will help keep cold air movement from entering your exhaust pipe and house.

Spray Foam

For a cheap and easy solution, consider using spray foam to seal holes and cracks around any bathroom exhaust systems in your home.

The increased moisture in a bathroom can cause wood rot, mold, and more humid air, all of which can cause swelling and eventual degradation of your walls and seals. Keep everything sealed tight with a little bit of foam.

Keeping up-to-date on materials used for home repair and projects is an ongoing task, one fraught with learning you were ill-informed in the past. With new understanding comes new insight, stay privy to the best materials to get the job done right.

Ways to Prevent Air From Entering Bathroom Vent Fans

The bathroom exhaust is composed of several components, such as the bathroom fan, fan housing, vent hood, exhaust duct, and exhaust pipe, all of which contribute to the amount of air movement in your home and bathroom. There are several ways to insulate and prevent cold air from entering your ventilation system.

set of ventilation grills

Clean or Replace Your Backdraft Damper

In order for your ventilation system to operate efficiently, you need a clean backdraft damper. As the name suggests, its use is to prevent air from traveling back up the exhaust duct and vent.

You should clean your backdraft dampers at least twice a year, it’ll save you money in the long run.

Insulate Your Home

In order to save money and prevent cold air from traveling through the bathroom and house, you need to install insulation. Key areas that should be insulated include the attic, ductwork for any bathroom exhaust fan or ceiling exhaust fan.

Keeping your doors properly sealed with weather stripping or sealant will help prevent cold air from entering the home and bath space.

Exhaust Fan

bathroom ventilator

Exhaust fans draw the air particles from a room to outside of the home, helping to eliminate bathroom odors and the likes. Often times the ventilation in a house is connected, such as the exhaust fans and ducts of the bathroom and kitchen, this can cause air infiltration to seep to all areas of your home.

Make sure that your bathroom exhaust fan has a flapper damper, which prevents cold air from outside from entering, and clean it regularly.

You can also install or upgrade any preexisting wall gasket to help keep cold air from entering the bath fans.

See Also: How to Replace a Bathroom Fan and Light Combo

Insulating the Exhaust Duct

As mentioned earlier, foam is a great material to use to seal any exhaust ducts around the fan box or any kitchen range hoods. Make sure to use mastic or metal tape with the foam when sealing the exterior of the ducts.

Keeping your ductwork properly sealed will save you money and keep heat contained within your home and bathroom.

Clean Your Fan Blades

At least once a year, clean your blades to ensure they’re properly working. A little routine maintenance can go a long way in saving you money on the electric bill.

plastic exhaust fan

Close Vents

If you have rooms that aren’t in use or that are poorly insulated, then you might want to close the vents leading to those areas of the house. This simple task can help keep your home distributing heat more efficiently and keep your bathroom from getting cold.


Keeping the shades and curtains drawn on your windows can go a long way to helping provide some needed comfort and warmth in your bathroom. Although it’s not associated with the vents at all, curtains and shades on windows help prevent infrared light, heat, from escaping. So, if it’s cold or nighttime outside, then keep those curtains closed for a little extra insulation against the elements.

Hire a Professional

If crawling through your attic and insulating the bathroom exhaust fan and vent pipe doesn’t seem like the job for you, then hire a general contractor to get it done.

Being familiar with the trade, they’re bound to know just what to do to prevent cold air from entering through your fan duct vent in the bathroom.

There’s no need for cold air to be circulating throughout the house unnecessarily. If you have an issue with cold air entering your bathroom exhaust, then consider taking some of the advice listed above to remedy the situation.

More Resources for Help on Bathroom Vents

installing a vent

Fan Manufacturers

All of the information you could ever want on dampers, bathroom vents, different types of exhaust pipe, and how it influences airflow and direction can be found on the manufacturer’s web site.

Manufacturers want you to buy their products and they’re willing to educate you on the benefits and drawbacks of purchasing certain types of fans, hoods, exhaust systems, and a backdraft damper that’s right for you and your needs.

They want the sale and you want the proper information, it’s a win-win scenario.

Check out a Q&A Forum

Someone out there has had the same dilemma as you, so you might as well get an idea of how to tackle the problem by listening to their advice.

The q a forums can provide a lot of helpful information on different types of fan dampers, bathroom exhaust fans, doors, and all the information you need to make an informed decision.

DIY Network and Magazines

If you’re a fan of watching the process of home repair and upgrades from start-to-finish, then you should check out the DIY network for all kinds of tips on bath fan insulation, cleaning, and backdraft prevention in a home’s ventilation and exhaust systems.

Get expert advice on all matters related to home upkeep, tips on bathrooms, and eliminating humid air in your home.

When it comes to bathrooms, fans, dampers, and how to use and install flex duct, you can almost always benefit from multiple resources before starting a project.

Installing a ventilation grill

There’s more than one way to maintaining the proper moisture and temperature level in your bathrooms and preventing mold in the process. Keep on top of simple routine maintenance and help prevent mold, mildew, and cold air from entering your home and bathroom exhaust fan in the process as well. Being a homeowner isn’t an easy endeavor, there’s no landlord to call when a problem arises.