Your crawl space is finished with pressure-treated walls and a plastic vapor barrier on the floor — but the walls are still bare concrete in an uninsulated cavity. Every spring, that wall sweats because there's no thermal break between the cold ground and the conditioned space above. 1-inch extruded polystyrene bead-board. 4-foot by 8-foot sheet. R-5 per inch closed-cell XPS construction — enough thermal break to shift the dew point away from the concrete in all but the most extreme conditions, without the cost of a thicker board for the full perimeter. Standard on crawl space wall insulation across northeast Nebraska and northwest Iowa — the bead-board that goes on the concrete wall before the stud bay goes up. In stock at Crofton Lumber (Crofton, NE) and Akron Lumber (Akron, IA) — ready Stocked at Crofton Lumber and Akron Lumber.