Chapter 7, Section 701.10, Combustion Air Ducts, is hereby deleted in its entirety and the following provisions shall be substituted therefor:

Combustion air ducts shall comply with the following: [NFPA 54:8.3.8]

(1) Ducts shall be of galvanized steel or a material having equivalent corrosion resistance, strength, and rigidity. [NFPA 54:8.3.8.1]

Exception: Within dwelling units, unobstructed stud and joist spaces shall not be prohibited from conveying combustion air; provided, that not more than one fireblock is removed.

(2) Ducts shall terminate in an unobstructed space, allowing free movement of combustion air to the appliances. [NFPA 54:8.3.8.2]

(3) Ducts shall serve a single space. [NFPA 54:8.3.8.3]

(4) Ducts shall not service both upper and lower combustion air openings where both such openings are used. The separation between ducts serving upper and lower combustion-air openings shall be maintained to the source of combustion air. [NFPA 54:8.3.8.4]

(5) Ducts terminating in attics shall not be screened and the combustion air opening shall be provided with a galvanized sleeve of not less than 0.019 inch (0.48 mm) (No. 26 gauge) steel or other approved material extending from the appliance enclosure to at least six (6) inches (153 mm) above the top of the ceiling joists and insulation. [NFPA 54:8.3.8.5]

(6) Intakes for combustion-air ducts located exterior to the building shall have the lowest side of the combustion-air intake openings located at least twelve (12) inches vertically from the adjoining grade level. [NFPA 54:9.3.8.8]

(7) Horizontal upper combustion-air ducts shall not slope downward toward the source of combustion air. [NFPA 54:9.3.8.6]

(8) The remaining space surrounding a chimney liner, gas vent, special gas vent, or plastic piping installed within a masonry chimney flue metal or factory-built chimney shall not be used to supply combustion air unless it is listed and shown in the manufacturer’s installation instructions. [NFPA 54:9.3.8.7]