glad I could help.
You'll definitely want more than 2/12 if you get snow, if 3/12 is all you can get, brace it a LOT and what ever size boards you were going to use, go bigger and closer together. you're spanning more than 12 feet? I wouldn't go under a 2x8 and I'd put them 12" on center. As aart said, you don't want to lose a roof to a snow load and at 3/12 it's going to take a long time to run melt and run off, unless I'm reading that you're going to be out there clearing it by hand?
You'll definitely want more than 2/12 if you get snow, if 3/12 is all you can get, brace it a LOT and what ever size boards you were going to use, go bigger and closer together. you're spanning more than 12 feet? I wouldn't go under a 2x8 and I'd put them 12" on center. As aart said, you don't want to lose a roof to a snow load and at 3/12 it's going to take a long time to run melt and run off, unless I'm reading that you're going to be out there clearing it by hand?
since the last picture I've got the other wall fenced too! It's almost done and ready for hens!