All chimney terminations must extend a minimum of 3 ft. above the roof, and must be at least 2 ft. above the peak of the roof if within a horizontal distance of 10 ft. from the peak. This same rule must be followed if the chimney will be within 10 ft. of an air conditioning unit or another chimney.
If you have a chimney chase, a 2 in. minimum horizontal distance from the chimney must be maintained on all sides. Also, the chimney must extend a minimum of 1 ft. above the chase.
Fig. 2: Chimney within 10' of peak
Fig. 3: Chimney 10' or greater from peak