Due to the fact that China’s steel structure building technology is still in the exploratory development stage and the market competition, after the investigation of the completed steel structure buildings, there are varying degrees of roof leakage phenomenon after the steel structure buildings are completed and put into use. Roof leakage has become a common quality problem of steel structure buildings.

Generally speaking, the water leakage of color steel plate roof is mainly caused by self tapping screw, overlapping of color steel plate, roof ridge tile, self piercing rivet, deformation of color steel plate caused by people on the roof and rainproof glue falling off of decorative parts such as lighting windows.The corresponding leakage points can be mainly divided into the following points:

1, roof screws and fasteners leakage

        This phenomenon mainly occurs in the double-layer color steel plate and single-layer color steel plate roof. During the construction process, the tapping force is too heavy and too light, and the self tapping rubber gasket may deform, fall off or form concave surface, resulting in water leakage on the roof. Through the accumulation of thermal insulation cotton, a small amount can make a lot of water leakage.In addition, one of the important reasons for water leakage is that the self tapping position is not correct and the purlin under the color steel plate is missed and the hole is directly formed.This kind of water leakage may not be obvious in the single-layer color steel plate roof structure without thermal insulation system, which is mainly due to the direct dispersion of rainwater through the contact part of steel plate and purlin, and may not drip rapidly. 

2. Water leakage at lap joint of color steel plate

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        The horizontal lap joint and vertical lap joint, and the lap joint of color steel plate have water leakage. If the tile wave of color steel plate is too low or the rainfall is too large to exceed the tile wave, it is easy to form large-area water leakage, and it is not easy to detect the leakage point. Once it is formed, it is difficult to maintain, which is more common in arc roof.The main reason is that the lap joint between the two plates is not tight, the self tapping thread is not fully filled, forming a gap and so on. 

3, roof tile leakage

       In the light steel structure roof construction, water leakage caused by roof ridge tile is also a common phenomenon.In the rainy season, especially when there is a large amount of rain water, the splash of rain water passes through the gap between the two color steel plates at the lower part of the ridge tile, forming a large area of leakage.

        After understanding the structure of color steel plate roof, possible leakage points and causes, we will talk about the treatment scheme.Combined with many years of construction practice experience, two leakage schemes are proposed

1The whole roof should be waterproof again

       This scheme can make the color steel sheet roof form a waterproof layer of integral connection. Self adhesive membrane is recommended for waterproofing of urban engineering.Self adhesive membrane is a kind of waterproof and sealing material which can be bonded with the base surface by itself, which can be divided into tire self-adhesive and tire free self-adhesive.It is composed of tire self-adhesive upper and lower self-adhesive adhesive, and the upper covering is made of ethylene film and the lower layer is strippable silicone oil film.Tire free self-adhesive is composed of self-adhesive, upper vinyl film and lower silicone oil film.The product has self-healing property, that is, the coiled material will automatically integrate with these objects when encountering puncture or hard objects embedding, and can still maintain good waterproof performance.And the material with pure metal aluminum foil on the upper surface has the function of heat resistance and heat insulation.The temperature of color steel tile can be reduced by 5-10 degrees in summer.

2Waterproof treatment shall be carried out for roof screws and fasteners, overlap of color steel plate and roof ridge tile.The construction process is as follows: cleaning the base course → painting the base course to treat the waterproof materials → adding the construction of the reinforced layer → brushing the waterproof coating.

       The above two schemes can effectively control the leakage of color steel plate roof, and the specific selection can be judged according to the construction area and other factors.