crown will have a slight slope to direct water, snow, and sleet off of the crown and onto the roof.
But it’s not just a proper slope that determines the effectiveness of the crown – it’s the thickness and edge as well!
In order to stand up to the constant abuse of the elements, a proper crown should be at least 3 inches thick at its thinnest point. Proper thickness helps ensure that the crown won’t deteriorate prematurely. Additionally, the crown’s drip edge should extend at least a couple of inches past the chimney stack so that all the moisture running off of the crown doesn’t go right down onto the masonry of the chimney or the surrounding flashing