How is the roof built up? 屋顶是什么结构？

0.37 mm outer sheet + 75 mm fire-resistant insulation + 0.27 mm coated ceiling sheet (effective width 831 mm).

0.37mm 外顶板 + 75mm 耐火保温层 + 0.27mm 彩涂吊顶板（有效宽 831mm）。