The new house I bought the year before last, the outer wall of the bathroom was damp, and there were

The waterproofing of the house is not done, and the water is in it, and it depends on the situation of going up and down the stairs. Make it easy to make changes early. The waterproofing is not done well, and the quality of the house is also a problem.

Which wall in the bathroom is the shared wall of your own room, or the wall shared with other homes, or your own partition wall? If it is the wall of the building that is damp, it is the reason for waterproofing, and if there is a window, it may be that the window is not well sealed. Or there are pipes for water supply and water on the façade of the wall, depending on the scene, comprehensive consideration, there are many reasons, it may also be that your bathroom exhaust is not good, the humidity itself is large in summer, and frequent water use is also possible.

The problem of waterproofing. It is possible that the waterproofing is too low.

If it is the back wall of the bathroom, you can first check whether there is water seepage in the bathroom, if so, you need to carry out waterproof treatment on the wall of the bathroom, and then repair the damp and peeling place on the wall.