I got a heavy duty tarp off Amazon, covered the area the ex-pen was going to go over and then just taped down the edges of the tarp. Worked really well for me. Normally, I'd just do bare floor, but I'm in a rental and the landowner frowns on messes of any kind on his floor. Not to say I didn't take the pup out often enough that that was ever a problem. But he still frowned on the idea of the floor being unprotected.