Hi,
I was in a similar place earlier this summer. I have 4 chickies and was going through all the different ways I could make their coop when I came across a children's playhouse at our local big box hardware store. It had been marked down to a price that I could barely buy the parts for, so i bought it and put it together for the girls. It's 4' x 4' x 6' at the peak. It has a lovely dutch door and two windows. I had to build a floor for it. I put it up on 4"x4"s and closed the space off with chicken wire. I live in Colorado, where it can get chilly, so i insulated it with 1" bead board and then covered that with a coated masonite that I held in place with glasers points. I covered the windows with 1/4" hardware cloth and put the reflective bubble pack that's used as an insulator on the inside roof.
I added a roost and put in a dog door as their in and out door. As for room for their food and water, I added 2"x2"s across at the top of the walls and suspended the food and water containers from there. As it turns out, the girls prefer to roost way up there than on the roost I provided. I'm amazed that they can get up that high in such a narrow space, but they do! I did have to put a slanted board over the food container though, because the kept roosting over it and pooping into it. (Silly girls)
We all seem to be quite happy with it. I would like a bit more space, but they have room to move around and flap their wings. The spend most of the day outside anyway.
Hope that helps!
(ps) I got my first eggs today! I'm so excited and surprised by them. We only have 10 hours/day of sun and I haven't put a light in the chicken hut, so it was a happy sight to see!