My coop was from freecycle, 6'x12' and now that I am expanding our flock, so I went on Craigslist and found someone getting rid of 2 12'x16' sheds. I disassembled them and now I have put a 12'x12' addition on the original coop so finished size when I am done with addition will be 18'x12'. I guess it helps that I am a "shop" teacher and I am able to do all the construction myself.