[unclebilly]

I built one this winter for my water cistern. It is 10X14 and I bought a kit and then modified it. I added a foot to the height, put on a 16" overhang, insulated it, and installed a 36" house door.

To do it again, I would stick build it from scratch.

For what you want, at Costco, they have the decent sizr plastic graden sheds on for $1000 right now. They go up quick, don't need paint, and you could run a wall down the middle and cut a door in one end for the chickens.