Gah, I think all my planning was for naught, LOL. I have a 4x4' brooder box for my babies, I was planning to keep them there for a week or so until I build a hover brooder to go in the big coop. I moved the box into a 15' by 10' room, because it's a bit warmer in there than the coop, (my coop is 3-sided), but my son just brought up a good point. I don't have any windows in that room. It's not a sealed room, per-say, but the ventilation is minimal. (During the night, during the day I can open the doors, but the point of putting them in there was to be able to maintain the temps for the first couple weeks) Is ventilation an issue NOW?