Depends on how slippery your roof material is. (Asphalt shingles verses metal)
A 45 degree angle is excellent to make sure the snow slides off.
30 degrees might be fine, if you use a slick roofing (like metal).
Nice explanations! :clap
I actually prefer Dutch doors.... and outward opening doors because outward opening doors are more secure against dogs jumping on them... and my carpentry skills suck. :idunno
The Dutch doors are so the bottom half stays closed all winter, I only open the top half...