The mesh on the ground is designed to stop digging predators. They come up to the fence, and try to dig under it, but can't since when they dig, they hit more fence. What type of predators are you trying to counter against? What type of fencing are you using? How big are the openings in the fence material? In protecting the coop itself, what is the coop floor made of? These are important to consider when building your chicken fortress! As a general rule, chicken wire is good for keeping chickens in, but does little to keep predators out. Dogs, raccoons and other animals can rip chicken wire apart and get into the coop. Stronger fence, like field fence with 2"x4" openings keeps some predators out, but allows larger ones to reach in and grab the birds, and smaller ones can fit through openings you would swear they could not. I saw an adult oppossum fit through a chain link fence opening 2"x2" as it was being chased by my dogs. I thought for sure he was going to get stuck! The best coops usually use 1/2" hardware wire. It has really small openings, and is a heavier gauge wire than chicken wire. I used two layers of fence on my coop / run. The outside layer is 2"x4" field fencing. Keeps bears, bobcats etc out. Then I have another fence layer on the inside of 1/2" hardware wire. I've had it for 3 years now, and the outer fence has been attacked and bent up a bit, but nothing has ever gone into the coop or run.
