The Henry 990-31 Protection Board is a continuously extruded flexible twin wall board made of polypropylene copolymer. 990-31 Protection Board provides protection for all types of waterproofing membranes.  The Henry 990-31 Protection Board is used as protection of waterproofing membranes against possible damage during backfilling on a wide variety of applications such as foundation walls, roof decks, terraces, planters, promenades, etc. Its lightweight feature makes 990-31 ideal to use on vertical applications.