2113.11.2.3 Multiple passageway.

Masonry chimneys containing more than one passageway shall have the liners separated by a minimum 4-inch-thick (102 mm) concrete or solid masonry wall.

2113.11.2.4 Termination height.

Chimneys serving appliances that operate at greater than 1,000°F (538°C) shall extend at least 20 feet (6096 mm) above the highest construction, such as roof ridge, parapet wall, penthouse, or other obstruction within 50 feet (15 240 mm) of the chimney outlet, whether the construction is on the same building as the chimney or in another building. However, such construction does not include other chimneys, vents, or open structural framing. Any chimney located beyond 50 feet (15 240 mm) from such construction but not more than the distance determined from Equation 21-2 and Table 2113.9, shall be at least as high as the construction.

2113.11.2.5 Clearance.

A minimum clearance of 4 inches (102 mm) shall be provided between the exterior surfaces of a masonry chimney for medium-heat appliances and combustible material.

2113.11.3 Masonry chimneys for high-heat appliances.

Masonry chimneys for high-heat appliances shall comply with the provisions of Sections 2113.11.3.1 through 2113.11.3.4.

2113.11.3.1 Construction.

Chimneys for high-heat appliances shall be constructed with double walls of solid masonry units or of concrete, each wall to be not less than 8 inches (203 mm) thick with a minimum airspace of 2 inches (51 mm) between the walls. Alternate chimney designs for high-heat appliances constructed with radial brick shall be permitted subject to the approval of the commissioner.

2113.11.3.2 Lining.

The inside of the interior wall shall be lined with an approved high-duty refractory brick, not less than 4 1/2 inches (114 mm) thick laid on the 4 1/2-inch bed (114 mm) in an approved high-duty refractory mortar. The lining shall start at the base of the chimney and extend continuously to the top.

2113.11.3.3 Termination height.

Masonry chimneys for high-heat appliances shall extend not less than 20 feet (6096 mm) above the highest construction, such as roof ridge, parapet wall, penthouse, or other obstruction within 50 feet (15 240 mm) of the chimney outlet, whether the construction is on the same building as the chimney or on another building. However, such constructions do not include other chimneys, vents, or open structural framing. Any chimney located beyond 50 feet (15 240 mm) from such construction but not more than the distance determined from Equation 21-2 and Table 2113.9, shall be at least as high as the construction.

2113.11.3.4 Clearance.

Masonry chimneys for high-heat appliances shall have approved clearance from buildings and structures to prevent overheating combustible materials, permit inspection and maintenance operations on the chimney and prevent danger of burns to persons.

2113.12 Clay flue lining (installation).

Flue liners shall be installed in accordance with ASTM C 1283 and extend from a point not less than 8 inches (203 mm) below the lowest inlet or, in the case of fireplaces, from the top of the smoke chamber to a point above the enclosing walls. The lining shall be carried up vertically, with a maximum slope no greater than 30 degrees (0.52 rad) from the vertical.

Clay flue liners shall be laid in medium-duty nonwater-soluble refractory mortar conforming to ASTM C 199 with tight mortar joints left smooth on the inside and installed to maintain an airspace or insulation not to exceed the thickness of the flue liner separating the flue liners from the interior face of the chimney masonry walls. Flue lining shall be supported on all sides. Only enough mortar shall be placed to make the joint and hold the liners in position.