Moisture Proof Plasterboard for Commercial Projects: Bulk Supply, Custom Sizes and Quality Control On a large project, whether the board is moisture resistant is settled early. What decides whether the programme runs is whether the mill can hold the same specification across a container-load order, cut to your sizes, and prove quality batch by batch. Five Questions to Ask Before You Order Which standard and grade is the panel declared against — ASTM C1396 WR, EN 520 H1/H2, AS