I am not a chicken coop engineer, at least no yet.
I copied a design that was selling rather well in the area even though the price was higher than I thought any one would pay.
It had 4X4 posts on each corner that were cut to length to match the slope of the ground and set on flat cinder block that were set into the ground so they were flat.
It was made out of plain 3/4 plywood on all sides and top, and had a wire mesh floor.
It was so god awful heavy that once the sides, floor and posts were put together, it was placed where it will stay!
Then the roof, nest boxes, windows, doors and perches were installed.
There were 2 windows, one was removable and had mesh covering it as well, one was on the front, one on the right.
The main access door on the left with the chicken door and ramp next to it.
It was 4 foot wide by 4 foot long and 3 feet tall on the front and 4 feet tall on the back where there was a wall long hatch/door to access the four nests from the taller back wall.
I used home building style of shingle roofing.
I used some left over latex paint she had left over from painting the house and looked as good as the ones the hardware store was selling.
And even though she lived in a upper scale area the local hardware store was also the feed/animal/farm supply store.