I have 6 Silkies, none are chicks, but a couple are pretty small. They are in a small henhouse 4'x 6' at night with 5 large buff brahma hens. The henhouse is completely sealed except for a couple of small openings and a row of vent holes at the top of the henhouse. I hung a 100W bulb from the center of the henhouse, but each morning, the water dispenser (like the kind hamsters and gophers use) had frozen..not completely but almost, so it must drop below freezing in the henhouse. I have about 4" of pineshavings on the floor of the henhouse (some of it is mulching, so I have to keep turning it), but the temps have been in the mid-teens a couple of nights here and it has not seemed to affect my Silkies. I am also putting 3 tiny bantams (really belong to my neighbor, but sleep in exposed conditions up on top of the hen pen) inside with my Brahmas and Silkies when temps drop below 32 F at night. The Silkies sleep in the deep litter on the floor, all bunched up in a group, so I'm assuming that the combination of larger birds giving off plenty of body heat, a light bulb, deep litter, and huddling Silkies is what has kept them alive.
