Please critique: The Fortress of Chickentude

[aart]

I don't want my birds crowded! The coop is probably about 20 square ft so just shy of what I need

That's still crowded, IMO.
Overall prefab coop/run foot print(not including nests) is about 3x6'?
Any chance you can get a hold of an old shed?

 

[Cryss]

I guess kind of gives them another 4-5 ft of roost?

Roost space is important. That is not part of the 4sqft/bird coop equation. This refers to walkabout floor space. Anything blocking floor space needs to be subtracted from the available floor space. I think you'll be good temporarily by enclosing the entire prefab unit. It will serve until you build bigger which you want to get started on ASAP. Chicken math is a real thing too so build bigger than you need for your current flock! I'm building mine from pallets snd scraps wherever possible. If I had the cash I would have gone the shortcut route and bought a wooden shed from home depot, then cut ventilation, windows, and a pop door. Might be something to consider. You can do this.