I used a pitch (slope) of 2/12. My roof at the front is 48" high. At the back it is 36" high...and width of coop is 5 feet, so I am just at 2.4" per foot of slope roughly. That is a very shallow slope, but I would think if you are in a snowier area, a slope of 4/12 would be good and more if you could manage. So in essence, just try to have it slope 4" per foot from front to back. 

