Rats are super good chewers. I. Had one enlarge a one inch space to 2 inches. I wouldn't put wire down on the floor, the chickens can injure their feet and get toes caught while scratching. Just staple hardware cloth around the parameter of the coop on the outside, bend the wire so it makes a skirt on the ground. Cover that with dirt or rocks or whatever...grass. animals will go up to the coop, attempt to dig and run into wire. Once grass grows through the wire, they won't be able to pull it up. Don't enclose the coop so you can't see under it....great place for rats if you do. Rat love eggs, and they've been known to kill small chickens while they sleep......and eat their feet off. Gross huh. Haven't seen that personally, just wanted to scare you. If the bottom and sides of your coop are tight...you may not need the wire. Keep an eye on it, and don't let it be a hiding place under there.
