In central illinois there are multiple small companies that sell prebuilt small sheds and typically they also have small coops that are much better quality than any of the kits at TSC and other stores. They deliver them assembled. They definitely cost more but I think you will regret getting a...
Have you seen the article about making a cave with a heating pad? I haven't tried it but it seems like a good plan to me ill see if i can find the article and put a link here.