My second floor chicken coop is nearly done. I just don't have space anywhere in the winter at the ground level. My city has a winter parking ban, so all the cars have to be parked in the driveway all winter. I have a small lot, and it snows a lot here, so that by the end of the winter my entire yard is 5' high in snow, with shoveling the drive and the walk, and having the snow slide off the roof. So, the chicken coop needed to go on the second floor of the barn. I posted here a few months ago asking for advice, and received some helpful feedback. So, here is how it turned out. I decided to cut two new windows in the south corner of the 110-year-old barn. I was able to reuse historical windows from elsewhere in the house/barn. I have yet to finish adding the trim, but I think it will look pretty good. I constructed a 4x5 coop in the corner. I laid new 3/8" plywood on top of the old barn floor, and put linoleum over that. Pretty much all of the materials for the coop are reused. Since it is inside the barn, it doesn't have to be weather tight - there is a roof overhead! It is well-insulated and air-sealed, however. To let the chickens in and out, I left one pane out of the lower window. I constructed a removable chicken ladder that I only put up to let the girls in or out. The ladder comes down at night, and the barn get locked up.