the present invention provides coating material , insulation - containing building material products bearing the material and methods for applying the coatings to the building material products . the coating matarials possess one - way breathability characteristics with respect to water and aqueous solutions . that is , the coatings are essentially impermeable to liquid water and permeable to water vapor . vapor from water in insulation coated by the material may thus pass through the coating , whereas liquid water is effectively prevented from passing through the coating and entering the insulation .