I have just completed my three sided coop, built for the heat of Texas. It is built within my fenced in garden area as a secondary protection mechanism...mostly to keep them safe from my dogs and to allow free ranging where I need it the most! Austin is mostly limestone so I wasn't too worried about digging, but I put down wire all around the bottom of the foundation sticking out about 24 inches anyway. That will be covered with gravel to provide more barriers. The total coop and run is 8' x 14' and it is built in between some cedar and oak trees for shade. The roosts are level to try and prevent pecking issues.
My favorite features include the two compost doors...allowing us to easily drop in kitchen scraps and garden trimmings without having to unlock everything. I put in a door at the roost for easy cleanout, an external egg box, automatic watering system and a hanging feeder. I am using oak leaves as the flooring of the run and pine shavings in the coop. There is ventilation at the roof as well as a ventilated/flap window for cross breezes in the summer. i plan to hang a carpet when it gets cold to help cover the open side and prevent the wind and rain from getting on the girls