A vent connector shall not pass through a ceiling, floor,
or fire-resistance-rated wall. A single-wall metal pipe
connector shall not pass through an interior wall.
Exception: Vent connectors made of listed Type B or Type L vent material and serving listed appliances with draft hoods and other appliances listed for use with Type B gas vents that pass through walls or partitions constructed of combustible material shall be installed with not less than the listed clearance to combustible material.
Exception: Vent connectors made of listed Type B or Type L vent material and serving listed appliances with draft hoods and other appliances listed for use with Type B gas vents that pass through walls or partitions constructed of combustible material shall be installed with not less than the listed clearance to combustible material.
Vent
connectors for medium-heat appliances shall not
pass through walls or partitions constructed of
combustible material. [NFPA 54:12.11.13.2]