I agree yellowchicks. Just add some 2x4s for support and plywood as walls. I would leave one side open (with hardware cloth) for ventilation. Also use hardware cloth to cover the entire floor to protect the chickens from predators.
The coop is at least covered by hardware cloth not chicken wire, so it shouldn't be too bad and can be converted to a bigger one easily.
Edited by TillyPeeps - 11/12/15 at 5:46am