Section 27-870. Chimney connector construction

Chimney connectors except
  those serving incinerators shall be constructed of galvanized  steel  of
  thickness  conforming  to  the  requirements listed in subdivision(a) of
  this section or of equivalent materials.  Cleanout  doors  of  the  same
  material  as  the  connector or other equivalent means shall be provided
  for the cleaning of connectors. Tile pipe shall not be used as a chimney
  connector.
    (a) Thickness of metal. The thickness of galvanized steel for  chimney
  connectors shall be not less than that given in table 15-7.
 
      Table 15-7 Required Thickness of Galvanized Steel for Connectors
  ========================================================================
 
  Galvanized Sheet                                       Area of Connector
    Gauge No.                                                 Sq. In.
  ------------------------------------------------------------------------
       24                                                   less than 79
       22                                                   80 to 154
       20                                                   155 to 200
       16                                                   Over 200
  ========================================================================
 
    (b)  General. All chimney connectors shall be as short and as straight
  as possible consistent with their use and the required draft conditions.
  No chimney connector shall pass through a floor or ceiling construction.