The Barrier under concrete thermal insulation and vapor retarder is a high-performance, simple to use and labor saving product for all of your under-slab, under concrete, and radiant floor insulation projects. The Barrier's unique core material is an extruded expanded polystyrene (EPS) with a jobsite tough, heavy-duty three (3) mil poly film laminated on both sides. Adding to the Barrier's labor saving features, NOFP added a 2" flap of film running the sixty-foot length of the Barrier insulation with an aggressive double-faced adhesive on the bottom side of the overlap -providing a seamless vapor barrier. This extra material allows one roll to be neatly secured up to the next roll. All that your jobsite crew needs to do is to remove the release paper off of the double stick taped edge, compress the overlapping flap on top of the exposed adhesive, compress the edge - and you have a seamless system that will not allow the transfer of heat or cold and will retard the transfer of all forms of moisture increasing the overall efficiency of your radiant floor heating system.