I have an old shed, the inside dimension is about 12 feet by 14 feet. It also has a 2 foot wide, 14 foot long shelf about 6 feet up. I am planning on making this into a chicken coop with a run, and I estimated I can hold about 45 chickens, if I am going with 4 square feet per bird. Is this a good idea? 45 chickens seems like a lot for a shed like that...