All chimneys shall be built of brick, concrete, stone or hollow tile of such thickness and construction as hereafter specified. The walls of brick chimneys shall be not less than three and three-fourths inches thick, and shall be lined with fire clay flue lining. Concrete chimneys cast in place shall have walls not less than three and three-fourths inches thick, shall be suitably reinforced both vertically and horizontally and shall be lined with fire clay flue lining. Rubble stone chimneys shall have walls not less than eight inches thick and shall have fire clay flue lining. Hollow tile shall not be used in connection with exterior hollow tile walls, and the walls of such chimneys shall not be less than six inches thick. All chimneys built of hollow tile shall have fire clay lining.
(1977 Code Sec. 5-27)