Procedure: Fireplace or Other Combustion Appliance Vents
Expose the ceiling finish and framing on each side of the chimney chase. Install blocking as needed to create a four-sided framed box.Install sealant around joists and blocking to seal the chase-wall framing to the joist framing and at the corners of the chase. Install sealant along the top side of the joists and blocking in order to adhere and seal the sheet metal closure.Cut and install the sheet metal closure to fit over the chimney opening tight to the metal chimney, with overlap at each joint. Apply sealant between the metal closures where they lap, and between the metal closures and wood framing. Secure the metal closures to the wood framing with screws.Seal the metal closure to the chimney and at each joint with silicone sealant.Install an insulation guard around chimney using an oversized metal duct. Cut and fold tabs to keep the insulation guard spaced 3" from the chimney on the top and bottom. Size it so that the top edge is above the insulation level, including any additional insulation that may be added.Replace existing insulation and install additional insulation around the chimney insulation guard.
