I have chicks that are only about 2-3 weeks old. I couldn't stand the smell of them in my house any more so I put them in a 3' square brooder box my husband built and lined with black thick plastic and layed down straw. I put a 250 watt light directly over them pretty low and under the light it stays 85 degrees or so. The brooder box is in an insulated 6'X8' coop. we put actual housing insulation and sheet rock in there. We have another heat lamp outside the box for the 14 week old chicks I have in there. It stays pretty cozy in there, but will it be too cold for the new babies?