How to Insulate a Metal Flue Pipe

Insulate A Metal Flue Pipe

• 1

  If you are installing insulation around a metal furnace flue pipe, turn off your furnace and allow time for the pipe to cool down before beginning. Once the pipes are cool, take a flexible measuring tape and wrap it around the pipe. Add 6 to 8 inches to your measurement to allow for insulation overlapping.

• 2

  Cut enough aluminum flashing to fit around your metal flue pipe and insulation. Wrap it around the flue, adding an additional 6 inches for safety. Cut slots in the top of aluminum flashing and bend the tabs down to keep flashing in place. Cut slots around the bottom of flashing and bend down. Place the aluminum flashing around the metal flue pipe and staple the tabs. Seal any gaps between flashing and pipes with heat-resistant caulk.

• 3

  Lay your blanket insulation on the floor and roll it out. Using a utility knife, cut the insulation to the measurement taken. Wrap the insulation around the flashing, overlapping it several inches for thickness. Place insulation around the metal flue pipe until it fits tightly against the flashing.