(a) Chimneys with a smoke flue having no side or diameter in excess of 24 inches shall be built of eight inches of brick, solid masonry or stone. If provided with a standard terra cotta flue of not less than five-eighths of an inch in thickness, the walls may be only four inches in thickness.
(b) Chimneys having any side or diameter more than 24 inches, but not having an area in excess of 900 square inches, shall be lined with a firebrick lining four inches minimum thickness laid in fireproof mortar, for a distance of not less than two feet below the lowest smoke inlet and extending upward at least 20 feet. The remainder of the chimney shall have the same lining or may have a standard terra cotta flue lining. Such firebrick may be considered as a part of the thickness required for the surrounding walls, except in cases where there is an air space between such lining and surrounding walls. In such cases the surrounding walls shall be the full thickness required. In no case shall they be less than eight inches in thickness.
(c) All chimneys with a flue area greater than 900 square inches, and other chimneys subject to excessive heat, shall be lined with firebrick at least four inches thick and extending from below the flue opening to a height of one-fifth the chimney height for steam boilers, or to one-half the chimney exposed to temperatures of 800 to 1,200°F and for the full height for temperatures over 1,200°F. At least a two-inch air space shall be allowed in all cases between lining and the outer wall. The lining material shall not be considered as carrying any stress. This requirement also applies to smoke flues of high pressure (over 15 pounds pressure) appliances.
(d) Chimneys shall be finished on top with one of the following:
(1) A three-inch stone cap;
(2) A solid masonry laid up in cement lime mortar;
(3) A solid three-inch minimum concrete cap; and
(4) Cast-iron plates at least three-fourths of an inch thick.
(e) All chimneys shall be built at least four feet above flat roofs, or a minimum of two feet above the peaks of pitched roofs, and chimneys for iron cupolas and other similar purposes shall project at least 15 feet above the highest point of any roof within 50 feet.
(Ord. 1963-52, passed 5-6-1963)