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• The size of the roof hole framing dimensions depend on the pitch of the roof. There MUST BE a 1-inch (25.4mm) clearance from the vertical vent pipe to combustible materials. • Mark the roof hole accordingly. • Cover the opening of the installed vent pipes. • Cut and frame the roof hole. • Use framing lumber the same size as the roof rafters and install the frame securely. Flashing anchored to the frame must withstand heavy winds. • Continue to install concentric vent sections up through the ro