I have a pre-existing shed that is effectively sitting on the ground. About 2/3 of the base is crushed limestone and the last 1/3 is soil. I am replacing the 1/3 soil with additional crushed limestone, and I am adding a 1 foot perimeter around the shed of crushed limestone. I have read about adding plastic sheeting under the entire shed as a moisture barrier, but this will not be possible, since it is pre-existing and on the ground.
Should I apply this moisture barrier between the floor joists and the plywood that will be the flooring, or will this just trap moisture against the plywood?