For installation of 1/2" wall & ceiling panels and trims to wood or metal in high moisture or acidic areas, we recommend using stainless steel fasteners. #8-15 x 3/4" with a low profile  truss head or wafer head, will do a good job for this purpose. Locating fasteners every 24" on center; in the center of the slots provided along the nailng fin of the panel; or make a 3/16" hole centered on the width of the nailiing fin and 24" apart, for the screws as required. You want to provide for a little movement of the panels ( 1/64"-1/32"), do not over tighten screws to the nailing fin. Allow panels to acclimate to area before installation as per installation instructions.