Gotta be careful with fresh wood chips... I saw a case of someone who lost almost their whole flock to aspergillosis. It may have to be a certain type of tree or climate to make the perfect storm, but it does happen! It's on your radar now though... :highfive...
My coop floor is the same... I use hay, pine shavings, rice hulls... whatever. It's dry so it really doesn't matter much. Just whatever material you like working with. And yes, I'm in the PNW. I love it here!
My metal roof sweats something awful where the frame members are... on sunny cold...