Building a large size coop this spring and have a few questions. First off I live in central Illinois and winters can be harsh, is it a given that I insulate the walls? ( I probably will anyways). Also we will have approx 15-20 hens with one rooster, Do you recommend making wood boxes or buying plastic laying nest or is metal better? For that many hens how many nesting boxes would you put up? Thanks for your answers and any additional info/tips on building a coop would be appreciated. Happy New Year!