Be aware, every single surface will get coated with chicken dander. They shed heavily especially when growing. Also, they will perch at the highest point they can get to, so along your top most central beam. If you want to keep the chickens out of the rafters, you can run chicken wire to define the space they should stay in, and put a ceiling on it. Frame it out with 2"x4" and use chicken wire to partition. You could make a human work area or a brooder area, as well as using the rest for the coop. Chicken wire is great for keeping chickens in a defined location, easy to work with for that. Does nothing to protect against predators, but good to divide up interior spaces of coops and runs, and for temporary partitions. Also, I would seal your concrete and wood before you let them in there, or you will never get the poop smell out of the concrete, or the mites out of the wood if you happen to get them. Sealing the wood and concrete will make your life easier. Whitewash or outdoor paint or paint/epoxy with a slick surface easy to clean works for the wood. Garage floor sealant works for the floor. Then put your deep litter on top of the sealed floor - much easier to clean.
