In the two hundred year evolution of sheathing for houses, we’ve gone from boards to plywood to OSB (oriented strand board) and the latest entry, water-resistant treated OSB. The latter is sold as the ZIP-WALL System (a roof sheathing version is also available) and is marketed aggressively by Huber EngineeredWoods as the perfect substitute for the more conventional sheathing and house wrap system. Basically the product replaces the water-resistant/vapor-permeable house wrap barrier with a factory applied coating followed by a site applied joint tape.