Step 1: Create Flue Clearance

Be sure to wear safety glasses for protection. Cut the roof sheathing around the flue with a rotary saw. Use the saw only if there is enough clearance. The plywood must be thicker than 1/4" to avoid cutting into the actual roofing material.

If using the saw is not an option because the sheathing is too thin, use a wood chisel. Use the hammer and chisel to create a 1" clearance around the flue.