I'm sure others have said it already but let me add : I wish I had known that chicken math is a DISEASE that all chicken owners get. Period. Regardless of their initial intentions....so build as big as you can afford and remember reuse/recycle....chickens don't care what it looks like (your neighbors might)
My neighbor was just going to buy my eggs. Then she was going to get 3 hens. Then she got 7. 2 died(predators) so I gave her 2. Now she wants to know if her coop will hold 12. All in 6 months time. Shortly after I gave her 2 , I ordered 10 from a friend.
(And I won't tell you how many my coop for 6 is holding...thank god I built big and my SO didn't mind me taking over the part meant for "storage")
I'm telling you it's a disease....there is always another breed you want in your yard and you can't get just ONE....and so it goes.