crazy question. garage of course. no fowl unless you are commercialized farming needs a coop that big. but heres how to have best of both worlds....build the garage and then spend a lil more $$ and put a shed roof off the back and/or side and make that your coup. perhaps even wrap the roof around 2 sides and give them plenty of room. you can make it big as you want. but you dont want to go too big, it will look silly if the shed roof overpowers the asthetic lines of the A framed roof.