Both sides build their own houses, and the external wall leaks. Neighbors don't agree to mend the outer wall and ask how to mend the inner wall to prevent water leakage.

It is difficult to cement this joint. If it rains, water will flow down the joint. If your wall is not cemented, water will seep into the house between the bricks, right? Do you think it is possible to put a meter next door to the iron shed on your top floor, cover that seam, and install water pipes on both sides of the room so as not to leak water? However, the next-door neighbors all agreed. In the future, the neighbors next door had a grounding shed, and the two families negotiated to build a roof together.