I've had great luck with the 90 lb dog size dogloo and an XL wooden dog house with a flat roof. 4 cayugas fit nicely in the dogloo, although one always insists with sleeping with her butt outside of the door.
They switch between the two for nesting. The hen that lays first picks the nest box.
I'm adding 3 more to my flock and I plan on getting another dogloo for them. The flat roof dog house is big enough to fit all 6.