first of all, the moldy wall surface should be removed to the cement surface of the blank room, and the wall surface should be disinfected with disinfectant. After the disinfectant is dried, putty powder with strong water resistance should be used for painting. After the putty powder is completely dried, professionals should spray latex paint, and the latex paint should be brushed for 2-3 times, so as to achieve waterproof and durable effects.

Reasons for this situation:

1. Leakage of drainage pipes, hot water pipes and tap water pipes will cause the wall to be damp, and when it is seriously damp, the wall will produce mildew.

2. If the thermal insulation measures of the wall are not well done, external rainwater will seep into the room, which will cause the wall to be damp, especially at the junction between the balcony window and the wall, which can not be tightly sealed, resulting in the leakage of external rainwater into the room.

3. There are a large number of solar water heaters on the roof. If the roof is not waterproof for a long time, the installation screws of the water heaters are oxidized to produce cracks, and rainwater will continue to leak into the house from the roof.

4. If the doors and windows are not closed in time during the rainy season, a large amount of water vapor will adhere to the wall after entering the room, and mildew will occur on the wall if it is not dried in time.

5. When the heating pipe leaks, it will also cause the wall to be damp, especially the heating pipe that has been used for a long time without maintenance.