Our dogs are getting old and need more secure footing. So we're going to loose-lay room size pieces of new conventional carpet on top of a nicely finished wood floors. A couple of rooms. Some hardwood, some engineered. Loose-lay. No padding. Not wall-to-wall with tack strips. We're worried the coarseness of the underside of the carpet will scratch the wood floor finish, even though the carpet will not be sliding around like a rug since sofas, bookcases, beds etc... will, we hope, weight it in place. We plan to take it once a year to clean it and to clean up any dirt/sand that has made its way underneath.
We've thought of kraft-paper (either the thin smooth kind, or heavier textured kind that is like tar paper with out the tar) or plastic. Or something else? What would be best for protecting the wood finish for a couple of years?