What should I do if the building foundation sinks?

From your description, it should be a resident on the first floor. Ground subsidence will cause damage and leakage of underground pipelines, and floor drain will return to water. The window is deformed due to the deformation of the wall, and the sash cannot be closed. This kind of problem needs the coordination of the property management department. Need housing maintenance fund maintenance. The first floor needs to be excavated to connect the newly laid pipes to the outdoor water, and the windows need to be repaired. It is a part of the house, and it is a relatively large project. It should be maintained by the housing maintenance fund.