I have 2 girls that are approx 5/6 months old living in the garage until I get a coop built. They get out in the yard for a bit daily. I also have 4 chicks in the house under a heat lamp that were 1 week old on Monday. How old do they need to be before they can go to the garage with the big girls? The garage is not heated but they are free to move around out there. I was thinking at about 4 weeks maybe? What do you think?