We built The Garden Coop (google it) four years ago and insulated the house part with rigid foam insulation. It has withstood a few very cold Ohio winters and they have user photos of their coop in Alaska! We do put a heat bulb in there when it gets really cold for extended periods. I do...
We have a flock of 4 4-year-olds (originally 6, but 2 died in the last year) who are still laying regularly in our backyard coop and also have 6 6-week-olds (4 hens, 1 banty hen, 1 surprise banty rooster) that will be moving out of our enclosed porch (ugh--I had forgotten how dusty and messy...
