Bathroom Exhaust Fan Leaking Warm Air From Attic

This meetup leads to condensation and will drip water back to your bathroom.

Bathroom exhaust fan leaking warm air from attic.

If you have taken the proper steps to remove excess humid air from your home and you re still having condensation issues it might be time to check the attic insulation. The ducting of your exhaust fan should be properly insulated. The bathroom exhaust fan is terminating in the attic. Cold air is denser and heavier than warm air and wants to go down not up.

It can cause you a lot of problems with mold and mildew forming on the underside of your rafters and decking as well as getting into your insulation. If so it indicates there is a leak in the vent cap. The fan pulls warm moist air from the bathroom and distributes the air to the attic. When the exhaust fan is on the damper should on and vice versa.

Several different ways you can move that hot air to the outside. The tubing or the ducting of the exhaust fan should be insulated and vented to the outside. This can be the nails the sheathing the rafters and more. This cold pipe can cause the air inside the pipe to go from warm to cold.

The duct should be insulated. Many bath vents can be pulled down an inch or so since they have little clips holding them in place. The duct is now cold because the attic is cold. If so the pipe gets very cold when the fan is not in use.

Warm moist air from the bathroom condenses on the cool duct and runs down the duct to the fan. Insulation is responsible for keeping warm air inside your living space and out of the attic where it can lead to condensation. No it s never a good idea to have any exhaust fan in your home dump all that hot moist air in your attic. However you will be suffering more likely because of the poor insulation.

Actually depending on the prevailing winds at your site cold air may blow in or warm air may leak out. Pay close attention to check whether there is insulation around the duct. If not this is the problem and you can solve it insulating around the duct. This can also happen during the warmer months.

On a cold day the moisture in the air will condense on anything below the dew point. My guess is the bathroom fan exhaust pipe is located in a cold attic space. Make as short of a run as possible to a vent connector through the roof deck. The hot and humid summer air will condense when it hits the pipe made cold by the air conditioning system.

If you are concerned about air flowing through the vent just put a page of a magazine behind the fan grille and lock it in place.