Envirosheet 40-sq ft Premium 1-in Flooring UnderlaymentBoard compressive strength is 22 psi or 3000 lbs per sq ft load capacity with an R5 value, has less than 1. 5% water absorption and 0. 42 perms The panel is acceptable for roof, floor, and wall insulation in residential, agricultural, commercial, and industrial construction Raised square blocks and deep valleys with a laminated vapor barrier surface film on the bottom face allow for both water and air movement under the floor facilitating drying