We are installing a Hercules Uniclic laminate floor over a non-heated 4'crawl space. We were told to put down plastic then the underlay and lastly the flooring itself. A friend mentioned to us that you had suggested tarpaper rather than plastic for a vapor barrier. We would be most grateful if you could elaborate on this before we begin installation of the floor.
I use both items, tar paper and poly. I use Poly under laminate floors and I use tarpaper under real wood or laminated plywood floors. I urge you to follow the manufacturer's recommendations to make sure you comply with the requirements of the warranty on the flooring.