I couldn't tell where you're from (west virginia??). If it gets hot in the summer, I'd suggest having sun shade instead of solid boards along the back of the boxes to provide ventilation and keep it from getting too hot in the boxes, assuming the boxes are otherwise sheltered. My birds still used them (in hot parts of arizona) because the shade cloth made them feel protected. I made the compartments big enough for almost any breed, even though I had leghorns. about 14 inches to 16 inches. And a remnant of sheet vinyl for the floor covering.
We are glad you joined our flock!
Best wishes and have lots of fun! 
