My run is 4'x10' and bordered by 2x6's on edge. I am planning on filling with sand and gravel to a depth of about 4-5 inches. I have been thinking a lot about predator protection and decided I want to step up the rat proofing. Not in the least inspired by the rat I saw on the power lines two nights in a row. Rather than try to dig down and bury a perimeter of hardware cloth, I was thinking about laying it down across the whole floor of the run before I fill with sand and gravel. However, I don't want the hens digging into it much, if at all, as I can't imagine it's too good for their feet. So, how deep should I bury it? If it's covered with 4-5 inches of sand and gravel, is that enough? Or should I put it under the dirt a few inches before adding the sand and gravel (so it would be down 8 inches)? Thanks!