1. Water leakage at roof screws and fastenershenomenon mainly occurs in the double-layer color steel plate and single-layer color steel plate roof. In the construction process, the tapping force is too heavy, too light, self screw deviation, skew, etc., which may make the self tapping rubber gasket deformation, fall off or form a concave surface, causing the roof drip water leakage, and accumulating through the insulation cotton, the accumulation makes a lot, forming multi-point water leakage. In addition, the position of the self tapping wire is not right, missing the purlin under the color steel plate and directly forming holes is also one of the important reasons for water leakage. This kind of leakage phenomenon may not be obvious in the roof structure of single-layer color steel plate without thermal insulation system, mainly because the rain water directly disperses through the contact part of steel plate and purlin, and does not necessarily drop rapidly.