For coop space, does the height not matter as far as sq ft? We're planning 8ft L × 4ft W × 5ft T, the nesting boxes will be attached outside so they don't lose floor space. There will be 2 8ft roost bars just above the top of the nesting boxes and either 3 or 4 4ft roost bars 1.5-2ft higher than the lower ones. Around the edge about halfway up the wall will be an L shaped ledge with a ramp to get up there on 2 walls. We decided on 5 nesting boxes, 3 individual boxes on one side and 2 larger communal boxes on the other. We're planning to expand when we can afford more materials but does this sound ok for 15 chickens starting out?