The basic method of  building insulation layer of steel structure roof (from lower layer to upper layer):

On the steel structure, first lay a 0.6mm thick galvanized profiled board, then a 35mm thick hard rock wool board insulation layer, a PE moisture barrier layer, and a 100mm thick double layer on it.

Two stitches of glass wool, the last is 0.8mm thick vertical seam aluminum-magnesium-manganese alloy plate (or profiled steel plate)