The concrete can really suck the heat out of something. Once I brooded chicks from about 1-2 weeks of age on, in the dead of winter on a plain, OSB type shed floor, with only the shavings as insulation, with plenty of heat though. I'm getting ready to brood in the house in a mobile home, and because the floor is cold, I have 3 layers of cardboard and a small rug under the brooder cage. I'm brooding hatchery/mail order birds, though, which are probably not in quite as good a shape after 40 hours in the mail, as if you took them straight from your incubator though, much less let a broody raise them.One thing nice about where I'm at, is that I'm starting from a blank canvas and I can take your suggestions and improve upon my plans. I found this on the internet. I think it will address the brooder space that some of you have pointed out. This will give me almost 16 sq ft. If I put this in the garage, it will be on concrete. Will this be a concern, or should I have some plywood down first? I like this plan because you can take it apart and store easily and not take up too much space in storage.