scandiafowl
Songster
The first thing I recommend, PAINT IT! By painting the inside, you will seal off many of the places that creepy crawlies can hid. OSB gives them LOTS of places to do that. It cal also brighten up the inside of the coop for them and you. If you have chickens at some point you will have lice. I also recommend using cedar for roosts, in case you hadn't read that earlier, but don't paint those. Paint and poly coat doesn't stay on cedar well.
What kind of paint, color would you recommend? I'like the natural look