We have a rug on top of a waterproof rug pad, much larger than our dog's crate, and then a blanket on top of that, under the crate. That way, the blanket is pretty easy to pull out and wash. I keep it folded under, so that the dog can't pull the blanket into his cage. There's no sliding involved.

So, in order from the floor:

Waterproof rug pad

Rug

Folded up Blanket

Crate.

You have to address why they're chewing the walls? Too long in their crate? Not enough distractions or toys while crated? Is it used as punishment not security or relaxation?

There's not much you can put between the wall and crate that they won't chew instead. You have to address the behavior first.

Well said.... My Greyhound's crate is situated about six inches out from the two room walls in a corner - no wall damage.

Never peed nor pooed in the crate. See Jen K's post above.

I don't think I latch the crate door more than once a year - when someone visits that is terrified of all dogs.

I had Great Danes and a Rottweiler that did this when they were young. I never crated them, they had a dog door to a large yard, run of the house and plenty of toys and each other while I was at work. They all did it and I never figured out why but they outgrew it. Are your dogs under 2 years old? I had a friend whose Rottweiler did the same thing. None of these dogs ever did anything else destructive. The only thing we could come up with was that for some reason they like the wall texture or the paint. It was regular drywall. If you have another type of wall you could put them next to of course that would work. My friend taped plastic sheeting over the wall. Looks awful but saved the drywall until he outgrew it. Does anyone know why they do this? I would really like to understand it. They are not bored. I've even caught them doing it while I'm sitting right there.