The California Building Code is very specific as it relates to chimneys. The rules is referenced as the 10-foot, 2-foot rule. A chimney placed within 10 feet of the roof ridge must be a minimum of 2 feet above this ridge.

Homes are becoming very contemporary with roof pitches at 7:12 and even 9:12. A contemporary roof with a 9:12 pitch means it rises 9 inches vertically for every 12 inches horizontally.    

A quick and easy calculation to find your minimum height requirement is to multiply your roof rise by 10 and add 24 inch to find you minimum chimney height. For example with a 7:12 roof pitch, you multiply (7 x 10) + 24 = 94 inches or approximately 8 feet. Your main concern should not be if Santa can deliver all of his present on time, but if he has a ladder to even reach the top of the your chimney.