Maven, I gotta agree with Bee and Loanwizard. I'd let then out at least a little.
I raise mine different than most people, but here's what I do myself; When they hatch I leave them in the incubator for 24 hours to dry and get their legs, then they go into a small brooder with closed sides and a wire front for one week. At a week old they go into our big brooder with wire front, floor and sides. They stay there until the are five weeks old. At five weeks I open the brooder door and on the ground they go. Our brooders sit out behind our house under some big oaks and my grow out pen fence is about 50 0r 60 feet from the brooders all around. so basically the brooders sit in the center of the grow out pen.
You can see pictures of our brooders here. (The info is out of date, but it'll give you an idea.) I really need to update that darn page... maybe soon. https://www.backyardchickens.com/a/mississippifarmboys-chcken-blog
Anyway, at 9 weeks mine would already have been running loose on the ground for a month.
I raise mine different than most people, but here's what I do myself; When they hatch I leave them in the incubator for 24 hours to dry and get their legs, then they go into a small brooder with closed sides and a wire front for one week. At a week old they go into our big brooder with wire front, floor and sides. They stay there until the are five weeks old. At five weeks I open the brooder door and on the ground they go. Our brooders sit out behind our house under some big oaks and my grow out pen fence is about 50 0r 60 feet from the brooders all around. so basically the brooders sit in the center of the grow out pen.
You can see pictures of our brooders here. (The info is out of date, but it'll give you an idea.) I really need to update that darn page... maybe soon. https://www.backyardchickens.com/a/mississippifarmboys-chcken-blog
Anyway, at 9 weeks mine would already have been running loose on the ground for a month.