I'm not sure what "fully feather" looks like. I'v read all sorts of conflicting things. Basically, these girls are getting to big for my box, running around the living room at night and jumping back in before morning! ! And now I notice them maybe fighting a little? ? I want to move then to the garage, larger pen, with the heat light. They are 3 weeks today. The garage is covered and weather proof. It's 60 daytime and 40 nighttime. Can I?
When they have grown real feathers 4- 6 weeks .
Longs you have a heat source at night or a warm place they can huddle they should be fine ..
Cold chicks huddle & scream / peep