Thanks for the suggestions everyone. I decided that I would sister every other rafter so every other rafter is a double 2x4 on 16" centers. 9' span. I'll be laying perpendicular 2x4's flat on 16" centers to screw the corrugated roofing to. Surely that will be enough support.
The coop is separate from the attached run. The coop is 9x8. The run is 9x26. The run is an outdoor area where the chickens are secure and under roof but can forage and do what chickens do. The sides of the run will be covered with 1/2" hardware cloth and then 2x4 welded wire. The coop is an extension of my compressor room on the back of my shop. The whole chicken extravaganza borders our raised bed garden. Chickens will have no access to the garden. They do have a 900 sq.ft. chicken yard behind the run/coop.
I had a fence company do the 8' privacy fence that forms the chicken yard. It connects with my storage building and parking area behind my shop.
Here's the 9' section of privacy fence that will become the west end of the run and the angled gate connecting the storage building so I have access to the implement storage area.
I cheated and had the fence guys set all the posts for the run while they were here. I began the rest of the framing today.
Here's some pics of where I stopped today for reference. Back to get more 2x4's tomorrow and continue on Monday...
Coop before the run construction...
And here's how far I got on the run today..