When fully feather and/or don't need supplemental heat.
12 chickens x 4 sg ft = 48 sq ft minimum.
I have 2 nesting boxes for 8 hens. Rarely do I find an egg in the second nesting box.
A draft free place to roost. Nesting boxes.
Plywood, 2x4, screws (not nails) and 19 gauge 1/2" hardware...