Jimmy, don't have a decent darn set of Xray glasses so don't know
what the little devils are up to under there.
The typar is much tougher though than the poly tarp and I doubt they are chewing through it. I'm sure they have tunnels around under it
though. Main thing is they are not getting inside the cabin.
A pack rat may chew through it, never been around them. Suppose if it was a concern a person could trench down around the beams on the outside and skirt the beams with sheet metal. Long as they are not inside I don't much care what they are doing. The cabin is so easy to heat since I perma-chinked that I wouldn't bother with insulation in the floor if I had it to do over. Would
still put down the typar though for moister barrier.