What should I do if the attic leaks when it rains?

Is to decorate indoor furniture and so on to minimize losses.

Find a property first. The roof belongs to property management. They are responsible for this.

To be clear, water leakage is difficult to control. Because it is not only leakage, but also seepage. It's hard to find loopholes. Even if the whole roof is waterproof, it may not be able to prevent it. Therefore, once the water leaks, we must first make clear the responsible party. If it is within the scope of property responsibility, it will all be delivered to them, and you can cooperate more. There is also the issue of compensation, which requires a preliminary understanding in advance.

If it is your own house, there is no other responsible party. That is to find loopholes. If the water leaks badly. I can't find a loophole. Then make the whole roof waterproof, remove all the tiles again and check the top surface. Then lay the tiles. If there are cracks, throw away the broken tiles and buy them again.