I used 2x4 roosts over the 8\' spans. They should be a chicken\'s length apart, so they could be closer together for bantams. Mine are about 14 to 16 inches apart, but probably should be about 18\" for large fowl The first one, near the wall could be half that amount, but not too close to the wall or the chickens might sit there picking at the OSB. You\'ll see a small piece of OSB at the end of my roosts to prevent the birds from fighting between coops.
The nest pails (\"boxes\") are screwed to the wall. Keep an inch or so clearance between them and between them and the support boards, on the sides, to allow dropping to drop thru. Some birds will go on top of these pails and this will avoid a pileup of droppings. There is a photo from the bottom of the nest pails to show there isn\'t a bottom board or support that they rest on. The side support boards are there to support the perch and board in front of the pails that holds the shavings and eggs in.
The last photo shows some small breeding coops that don\'t have birds in them yet. They work great for trios of bantams or single LF hens with a cock left in for a couple days each week.