How to Insulate the Exhaust From a Downdraft Countertop Stove

Downdraft exhaust fans for countertop stoves do not require ductwork to go through your ceiling and roof. Instead the ductwork usually is under the countertop stove and goes directly out of the rear wall. Often the ductwork has a small gap between the hole in the wall and the outside diameter of the duct work. Insulating the exhaust from a downdraft countertop stove requires heat-resistant silicone caulk. Although this is not a major heat source, it is helpful to use a caulk that can handle the expansion and contracting of the ductwork without cracking or separating from the seam.

Heat-resistant silicone caulk
Caulk gun
Tin snips

Instructions

- 1
  Look for the run of galvanized ductwork that makes up the exhaust pipe for your unit. On a countertop stove, the ductwork is in the cabinet below the stove and usually goes through the nearest wall.
- 2
  Apply heat-resistant caulk to the seam between the inside wall and the exhaust duct with a caulk gun, if the seam is less than 1/4 inch wide.
- 3
  Cut two pieces of sheet metal into 12-inch squares with a pair of tin snips, if the seam between the duct and the wall is more than a 1/4 inch wide. Cut a half-moon shape out of one side of each piece with the tin snips. The half-moon space left in the sheet metal should be half the diameter of the exhaust duct.
- 4
  Apply a bead of heat-resistant silicone caulk on the bottom of each piece of sheet metal with a caulk gun. Position each piece around the kitchen exhaust vent pipe and press it down onto wall around the exhaust duct.
- 5
  Apply a bead of heat-resistant caulk around the seam between the exhaust vent pipe and the sheet metal with the caulk gun. Go outside and apply a bead of caulk between the outside perimeter of the exhaust vent cap and the outside wall.

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