Leakage
The leaking of the roof can be seen mostly in the rainy season. Leakage can either be because of a small crack or it can be due to a large crack.
If the roof has a small crack, it can be repaired easily by patching it. The patching of the roof is not possible when the cracks are bigger so you are going to need the roof replacement.
To check about the cracks, you have to climb on the roof and try to see between the tiles and measure the length of the crack. You can also estimate the size of the crack by the amount of water coming.