We have 8 day-old chicks arriving in about a month to expand our small flock of laying hens. At what age should I put the two groups together? I'm not in any rush to combine them; I'm basically asking so I'll know how to construct the new coop. If we can put the "babies" in with the grownups at 6 weeks, I would construct the coop differently than if I need to keep them separated for 20 weeks. Also, how much space do the babies need? I've read that 1 sq foot in a brooder is OK to start, and then move to 2 sq ft. How long will that last before they need the typical 4 sq foot in an outdoor coop? In case it matters, the grownups are 2 Australorps and 2 Easter Eggers and the babies will be 1 Salmon Faverolle, 1 Barred Rock, 1 White Leghorn, 1 Red Star, 1 Silver Laced Wyandotte, 1 Bantam Silkie, plus 2 other Bantams.