In the summer, there is no water leakage on the fifth floor, but there is a water seepage on the bat

This depends on the situation, if it is a leak in the public pipe, the two families discuss to solve it, obviously the fourth floor will suffer. If the branch water pipe leading from the fifth floor is leaking, of course, the fifth floor is responsible for repairing it. In short, distant relatives are not as good as close neighbors, it is best to solve the problem, don't take the cost too seriously, calculate it too clearly, otherwise it will cause neighborhood disputes, and it will be very troublesome in the future.

It is probably the water pipe originally embedded in the wall, the waterproof is done, and the surface is the problem, it may be the water pipe in the wall, aging and leaking.

The person directly responsible for the water leakage downstairs is your home, you are responsible, you can first check the specific cause of the water leakage, and make sure that the cause is solved, if the problem is not big, it will not be very troublesome.

Please describe the leakage on the roof of the fourth floor. Is the slab cast-in-place or the finished slab?

That's the time for decoration, and there is a problem with the renovation of the exhaust flue.