The leakage of concrete roofs mainly occurs in the roof expansion joints, roof walls, and roof pipes. The specific causes of leakage are analyzed as follows:

Conventional design of formal structural roof:

Reinforced concrete roof panel-insulation layer-cement mortar leveling layer waterproof coating-waterproof coil-dry hard cement mortar-floor tiles laying (cement mortar joint filling)

The roof expansion joint is the same as the daughter wall leaks, and the reasons are as follows:

Expansion joint function: Expansion joint is also called temperature joint, and its main function is to prevent cracks from occurring in houses due to climate change. Therefore, the contraction force under this area is much larger than that of other areas, and it is also a weak area for roof waterproofing.

The original waterproof layer fails to aging, and under the thermal expansion and contraction of the roof, and the pressure inside the structural layer, it breaks and peels off from the base surface, making the waterproof effect weaker. This causes rainwater to enter the insulation layer through the original waterproofing, and then flow into the room through the joint between the daughter's wall or the expansion joint and the floor slab, resulting in water leakage.

The perlite slabs in the insulation layer have a high water absorption rate. Due to water absorption and heat expansion, the pressure in the structural layer becomes increasingly greater, which breaks the original waterproof layer. This leads to increasingly serious water leakage.

During the waterproofing construction of the facade of the daughter wall, the roll material needs to be wrinkled when dealing with the yin and yang corners, and the bonding is not firm, causing water leakage.

Causes of water leakage around roof pipes:

When installing the pipe, the floor slab was penetrated, destroying the original waterproof layer. Moreover, there is no waterproofing construction around the pipeline. Due to the different materials of steel and floor materials and different thermal expansion and contraction coefficients, cracks stretched out between the pipeline and the floor. When it rains, water penetrates into the structural layer through the roof, and then flows into the room through the damaged parts of the coil and the floor, resulting in water leakage.