It's usually recommended to either have the fence extend underground or make a "skirt" around the run, extending out a foot or two, to stop digging predators, securing the skirt both to the run and at its outside edge. People also use things like paving stones or large rocks around the outside.
I would say,What could it hurt? I seen a fox lastnight in my yard.Today I am mounting my coop to a contrete slab.I am also gonna bury some hog-panels cut in half longways for thier run.That will give me 2ft underground.Plus I have a dog.I lost 2 chicks last week to something & you dont want that.
Agreed. You need to do one or the other. It's not just the digging predators. You'd be surprised at how small a gap between the bottom of the fence and the ground some of these things can squeeze through without digging. And your dust-bathing chickens can dig out a pretty good sized hole if they try.
I find it a lot easier to just lay an apron around the outside of the run instead of burying it and I think it is more effective. You don't have to bury it at all, just put something to hold it down for a little while and the grass will grow up through it and hold it down, plus the chickens will probably scratch some dirt over it. But removing the sod and putting it back on top gets the wire out of lawn mower and weed eater range and probably makes it look a little better. I suggest going out 18" to 24" with the apron, depending on how wide your roll of wire is.