1. The roof is a double-layer sandwich panel, and the roof joints are not waterproofed. Due to the thermal expansion and contraction caused by different roof materials, natural wind blows cause vibration of the color steel plate, causing opening of the roof joints. When it rains heavily, water penetrates into the insulation cotton through the joints. Due to the sealing of the lower layer, water accumulates in the insulation cotton for a long time, and the water flows from high to bottom, concentrated in the eaves. The eaves are cut, and there is no paint protection at this place, which is a weak part of the color steel plate anti-corrosion. Long-term humidity and no paint protection cause serious rust in the place.

2. Since the roof has not been thoroughly maintained and repaired, someone needs to work on the roof for a long time. The hardness of the paint itself is low. During the construction process, the scratches of construction tools and violent construction of color steel plates are very likely to cause the roof paint to fall off. Over time, due to the corrosion of acid rain, the oxidation of the natural environment, the parts of the roof paint to fall off from point to surface, starting from contagious corrosion. If not repaired in time, it will cause large-scale rust and perforation of the roof, affecting the stability of the roof structure. There are safety hazards and affect the normal progress of the roof.

3. When it rains, the rainwater washes away the floating embroidery in the rusty area and flows on the roof. The contact between the oxidized iron and the last rusted iron accelerates rust in other parts, causing flowing rust marks on the roof.

In the final analysis, the main reason for the leakage of color steel plates is that the roof joints are not well waterproofed, and repeated repairs cause wear of the original paint, loss of anti-corrosion protection, and the accumulation of water caused by water leakage accelerates the oxidation rate of color steel plates, causing large-scale rust in a short period of time.