The OMG Stainless Steel Roofing Fastener must penetrate steel decks a minimum of 3/4", wood plank decks a minimum of 1" and 1/2" through the underside for plywood decks. Using a screwshooter, drive the fastener until a slight depression is seen around the plate, or with very rigid insulation boards, watch for the plate to dimple.
Note: Care must be taken not to overdrive the fastener and fracture the skin of the insulation. Fastener must be tight enough so that the plate doesn’t turn. For steel decks, Factory Mutual requires that the fastener penetrates the deck at the top flute.