The only thing I would add is that if you live in a snowy area, don't do a flat roof. I have a flat roof and it's been horrible with snow on it. I cover the roof with a tarp to keep out moisture. I had a foot and a half of snow on it, which had to be removed with backs of rakes while I was on a ladder in the snow. Not fun. We've had snow all winter here in northern Nevada. Removed several times. Along with digging paths to the doors. I'll be putting a regular pitched roof with recycled metal probably. Not doing this again. So if you have weather, build accordingly. Remember, chickens are a lot of work, every day. Rain, snow or shine.
The only thing I would add is that if you live in a snowy area, don't do a flat roof. I have a flat roof and it's been horrible with snow on it. I cover the roof with a tarp to keep out moisture. I had a foot and a half of snow on it, which had to be removed with backs of rakes while I was on a ladder in the snow. Not fun. We've had snow all winter here in northern Nevada. Removed several times. Along with digging paths to the doors. I'll be putting a regular pitched roof with recycled metal probably. Not doing this again. So if you have weather, build accordingly. Remember, chickens are a lot of work, every day. Rain, snow or shine.