As a kid I spent time on my aunt's farm and she had converted an old horse stall in to a chicken area. The stall had half-split barn doors to a small outside paddock so they had stapled chicken wire around the existing fencing and over the top of the run and left the bottom door open to the outside. Basic nest boxes were mounted on the stall wall about three feet up and there were roosts that looked like a wide wooden ladder leaning up against the corner. I was only there in the summers, but I'm sure nothing much changed in the winter except maybe the big door to the paddock area was shut and the chickens just came and went through the small pop hole. This was Up North Michigan (the upper part of the Lower Peninsula) so I'm sure it got really cold but there was no insulation and I'm sure the stall was drafty. It was a really basic set up, but it was perfect for the flock. They didn't shut the barn up at night, but they always had a couple of farm dogs that slept out there.
My cousin just had her husband frame out "walls" with 2x4s inside her barn, framed and hung a basic door and covered everything with chicken wire. She bolted 5gal. buckets to the wall for nesting boxes and bolted various horizontal branches in the corner for roosts. Again, no added insulation inside the barn for her Michigan winters. Good luck with your project!
