The 1998 California Fire Code, Section 1109.7 requires that all chimneys used for fire places or heating appliance using solid or liquid fuel shall be equipped and maintained with an approved spark arrestor.
Approved shall meet the definition of a spark arrester as defined in the California Building Code, Section 3102.3.8.
Spark Arrester. The net free area of the spark arrester shall not be less than four times the net free area of the outlet of the chimney. The spark arrester screen shall have heat and corrosion resistance equivalent to (0.109 inch (2.77 mm) (No. 12 B.W. gage) wire, 0.042 inch (1.07 mm) (No. 19 B. W. gage) galvanized wire or 0.022 inch (0.56 mm) (No. 24 B.W. gage) stainless steel.
The spark arrester shall extend above the chimney to a height of not less than 1.3 times the minimum diameter or horizontal dimension of the chimney.
Openings shall not permit the passage of spheres having a diameter larger than 1/2 inch (12.7 mm) and shall not block the passage of spheres having a diameter of less than 3/8 inch (9.5 mm).