wellcome mark your shed and idea looks fine m8 but i would remove the 3rd plank from the bottom the full lenth and replace with chicken wire giving a 4 inch gap for ventaltion then put the same plank back on at an angle to keep the rain out do the the same with top plank along the back and it will be perfect for air flow in the loft two sputnics on the front and your ready to go the size of your sections make no difference its how many birds you have in each that matters m8 good luck with it