One of the outer walls of the house built by both parties is leaking. The neighbor does not agree to repair the outer wall and asks how to repair the inner wall without leaking?

This joint is difficult to seal with cement. If it rains, rainwater will flow down the joint. If your wall is not covered with cement, water will seep into the house through the joints between the bricks, right? Can you see if you can build a meter from the iron shed you built on your attic to the next door, cover the gap, and install water pipes on both sides of the house (in a herringbone shape) so that there will be no water seepage. But the next door neighbor needs to agree. In the future, if the neighbor next door wants to build an iron shed, the two families will negotiate to build a roof together.