How to Vent a Bathroom Exhaust Fan Into an Attic

The attic in a home is designed to accept the heat from the house and ventilate it outside.

An exterior pipe venting air from a bathroom exhaust fan can be vented into the attic instead, should you wish to avoid water and contaminants entering and clogging the pipe. You will need some household tools and with supplies from a hardware store. No electric wires are involved, nor will you be altering the structural integrity of the exhaust pipe.

Turn on the bathroom exhaust fan, then get up on the roof. Place your hand against the top of the exposed pipes exiting the roof, feeling for the one exhausting air. Mark this pipe with an "X", using the pencil.

Go into the attic. Place your ear against the pipes running from the floor through the ceiling. When you find the pipe that has air rushing through it, mark it an "X". Turn off the bathroom exhaust fan.

Return to the roof. Shake a can of fast-acting spray foam insulation for 10 seconds and spray the foam into the pipe's hole. Stop spraying once the hole is filled. Let the foam set for the amount of time specified in the instructions, then spray a second application of foam into the hole.

Return to the attic. Use the hacksaw to cut through the top end of the pipe that has an "X" on it, cutting about 5 inches below the ceiling of the attic. Cut through the bottom of the pipe, about 5 inches up from the floor.

Pull the pipe off the cut ends and place it away. Shake the can of spray foam insulation for 10 seconds and spray the foam into the top of the pipe protruding through the roof. Stop spraying once the hole is filled. Let the foam set for the amount of time specified in the instructions.

Things You Will Need

  • Pencil
  • Fast-acting spray foam insulation
  • Hacksaw
  • Ruler

About the Author

Marshal M. Rosenthal is a technology maven with more than 15 years of editorial experience. A graduate of Brooks Institute of Photography with a Bachelor of Arts in photographic arts, his editorial work has appeared both domestically as well as internationally in publications such as "Home Theater," "Electronic House," "eGear," "Computer and Video Games" and "Digitrends."