2. Light steel keel: the wooden keel is used as the edge dragon, and the light trough is made of wooden keel or joinery board. Where there is wood, fire retardant paint should be painted. Keels should be at least 50, with a spacing of 30 cm and suspenders with a spacing of 60-80 cm. A gap of 5-8 mm should be artificially reserved between gypsum board and board. Self-tapping screws on the surface of gypsum board should be recessed into 1-2mm, and be treated with anti-embroidery. It should be flat and strong.
3. Wooden keel: the keel should be at least 3*4, with a spacing of 30 cm and a spacing of 60-80 cm. Direct use of suspenders is prohibited.