The risk from larger animals like a large dog or an old boar raccoon is that they can tear hardware cloth if they can get a grip on it. This thread has photos that show it can happen. It doesn't happen often but it can.I remember reading somewhere that HC is good for raccoons, weasels, rats and so on, but less so for canids like foxes, dogs and coyotes.
Dog Vs. Hardware cloth... | BackYard Chickens - Learn How to Raise Chickens
Another possible point of failure is where your wire mesh fencing is attached to your run frame. If they get a good grip can they tear it loose?
The idea is that a heavy gauge welded wire fence would stop a larger animal and the hardware cloth would stop small critters that would go through the larger holes in a welded wire fence. I'm not a huge proponent of this because most critters that can get through the holes in the welded wire can climb above the 3 feet of hardware cloth. I have used it though to stop baby chicks from going through a welded wire fence where a broody hen could not protect them.The recommendation I’d seen was a double layer at the bottom (like the bottom three feet) with HC and welded wire fencing. Is that a thing? And if it is a thing, which layer would go on the outside?
How big are the holes in the welded wire fence? If the chick can easily get through those holes it would be hard for it to get stuck between the fences. I'd be less concerned about that with a 2" x 4" welded wire fence than a 2x2.So elsewhere someone had said chicks could get stuck between the layers if the welded wire was on the outside. Thoughts?
When you attach the hardware cloth to the welded wire, basically "sew" around the edges so a chick cannot get through. Don't leave any gaps big enough. You can attach the two fences with J-Clips, hog rings, short pieces of twisted wire, or thread a length of wire just like you would sewing a thread.
Probably doesn't matter. I think you could make an argument for either on the outside or inside. The main thing is to tie them together so they act as a unit.I guess what I’m looking for here is the reasoning behind which fencing goes on the outside.