Mine too are about a month old. I transitioned them during week three, by turning off the lamp and taking them outside for the day.
Now they live in the coop in a large wire dogcrate. 1 inch squares to the wire, so they can't get out and the big folks can't get in. I tried a huddle box, but they weren't having that. So now I put an old dog bed fleece over them when it gets cold. High 20's with wet mix came down last night, they were fine this am.
The biggest thing is to make sure they and their bedding is dry and not in a draft. Cold and dry is ok, cold and wet is a recipe for disaster.
Now they live in the coop in a large wire dogcrate. 1 inch squares to the wire, so they can't get out and the big folks can't get in. I tried a huddle box, but they weren't having that. So now I put an old dog bed fleece over them when it gets cold. High 20's with wet mix came down last night, they were fine this am.
The biggest thing is to make sure they and their bedding is dry and not in a draft. Cold and dry is ok, cold and wet is a recipe for disaster.