I got a late hatch this year and have babies that are 7.5 and 9.5wks old. All very feathered. Mostly feather footed breeds I.e. Cochins, d'uccles, silkies, etc. I've had them out in a brooder OUTSIDE with a 250ww red heating bulb over them on only one side of the crate and food and water away from it so they have to acclimate to the cold. Theyve done great! they eat in the booder in the cold areas when its about 0 degrees F outside. Last night I put them in the big coop (they go in during the day almost every day with temps at 20ish during day) with probably about 5-7" of bedding and no heat source. They run around like crazy during the day, digging, eating, pecking, etc. no signs of being cold. I left the 5 biggest ones out last night in 5deg F and they did fine, I put in warm water bottles. But now i'm wondering if im moving them out too fast or are they OK if they survive 5F nights already?