Section R. 400.18621 - Chimneys and fluesRule 621.
(1) A furnace or other fired unit shall be vented by smoke pipes to a chimney which is constructed of brick, solid block masonry, or reinforced concrete, which has an approved flue lining, which is properly erected, and which is maintained in a safe condition. A bracket chimney is not permitted.(2) The provisions of subrule (1) of this rule do not prohibit the installation and use of any prefabricated chimney that bears the label of approval of underwriters laboratories, incorporated, if it is installed and used in accordance with the specifications of underwriters laboratories, incorporated.Mich. Admin. Code R. 400.18621