Seal and insulate an exhaust fan

Not all types of vents must be sealed and insulated, but doing this prevents the risk of experiencing mould and damage to the structures in the garage. One type of vent which requires this operation is the exhaust fan. This has to be sealed because of the difference between the air inside the venting and the air inside the garage.

This guide will teach you how to seal and insulate a garage ceiling venting, in order to avoid condensation.

Necessary tools:

  • knife
  • duct insulation
  • caulk gun & silicone caulk
  • aluminum foil tape


  1. With the silicone caulk tube, puncture the seal inside and load the caulk tube into the caulk gun.
  2. Using the caulk gun, dispense the caulk around each seam on the venting. It’s recommended that you tool the caulk in, using your finger so that the bead has a 3/8 inch thickness and the seam is entirely covered. Now, following the manufacturer’s instructions you must let the caulk cure.
  3. You now have to measure the distance around the outside of the vent pipe-the circumference of the vent. The cut size for your insulation pieces will be obtained by adding 6 inches to the circumference of the vent.
  4. Using your utility knife, you must now cut the insulation at the measured length.
  5. You now have your desired insulation. All you have to do now is to wrap it around the venting. Pull it tight and secure it with aluminum foil tape (it’s recommended that you use 3-inch aluminum tape).
  6. The final step: cut the tape and the insulation untill all the venting is completely insulated.


  • When you install the insulation, don’t forget to put on a protection mask, because you run the risk of irritating your lungs.
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