Roof panel sandwich (Roof Sandwich Panel) consists of a double layer sheet, which is insulated with polyurethane foam. Due to the ribbed upper sheet of the roof panel (trapezoidal), there is a possibility of overlap and causing the roof to be sealed. Before using the roof panel, the first thing is to install the gutter and then cover the roof, and after completing covering the roof, the flushing sheet is used to finalize the work.