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• The masonry wall of the chimney, if brick or modular block, must be a minimum of 4 inches (102mm)
nominal thickness.
• A chimney of rubble stone must be at least 12 inches (305mm) thick.
• The chimney must have a fire clay flue liner (or equivalent) with a minimum thickness of 5/8 inch
(16mm) and must be installed with refractory mortar.
• An equivalent liner must be a listed chimney liner system or other approved material.
• Since an oversized flue contributes to the accumulation of creosote, the size of the flue should be
checked to determine that it is not too large for the appliance.
• The chimney should also be checked to ensure it meets the minimum standard of the National Fire
Protection Association (NFPA) Standard 211.
• A chimney support package must be used when a connection is made through the ceiling to a factory
built chimney.
• An approved thimble and chimney support package are
absolutely necessary
to provide safe clearances
to combustible wall and ceiling material.
NOTICE
: In Canada when using a factory-built chimney it must be safety listed, Type UL103 HT (2100°F)
[1149°C] CLASS “A” or conforming to CAN/ULCS629M, STANDARD FOR 650°C FACTORY-BUILT
CHIMNEYS.
FIGURE 3H
