The gauge (thickness) of the metal is an important material specification selected by the metal-roof-contractor. Gauge is inversely proportional to thickness; a lower gauge number means a thicker, stronger metal. For residential standing seam, 24-gauge steel or 0.032-inch aluminum is standard, providing a balance of cost and durability. Thinner gauges (like 29-gauge steel) are cheaper... https://kkroofspecialist.com.sg/metal-roof-contractor/