R-Panel. Liner, Roof, Wall. Panel verage: 36". Rib Height: 1-1/4". Rib Features: TrapOKAYoidal rib on 12" centers. Standard Gauges: 26 ga., 29 ga. A temporarytile option, R-Panel is a low-profile roofing and wall panel that can be applied over open framing or solid substrate. Available Material: Steel.