R-Mer Shield standing-seam roof system has a 2-in. high vertical seam with an extruded aluminum clip and top rail system said to provide unrivaled wind-uplift performance, ensuring watertight protection in harsh environments. The roof system can span open purlins on slopes to 1/4:12 and has a 1/2-in. clearance between the panel and substrate to increase ventilation beneath the panel. The one-piece clip and top rail provide thermal movement. A double bead of factory-applied seam sealant is isolated from the clip.