My hubby built an 8x8 large coop, featuring a metal roof, windows (covered in hardware wire) and linoleum floor. The girls enjoy an automatic door that opens into a small run, and they can be free range in a larger run when we are around to supervise.
Inside features a level roost with a poop board underneath it, and tile board to line the upper walls for easy cleaning. The lower walls are reclaimed 1x3s. there is insulation one the north and west walls. Because windows allow sun to shine on the nest boxes, I have added curtains for privacy and darkness!