Time to expand the coop. I am on the 9th revision of my coop design and am feeling pretty close!! I have a handicapped chicken who hops on one leg and cannot go up a ramp. I need to have the house at ground level and cannot elevate the coop. How can I keep rats and mice from moving in under the shed? I'd rather not pour concrete, I have a small city yard and will remove the coop if/when I ever sell the house. Should I put pressure treated wood right on the ground? Would gravel make it less inviting? I can put trim around the bottom edge of the shed but the little buggers could always dig under it. Thank you BYC!