If you are facing the problem of water leakage through the roof, you should contact the professionals and seek waterproofing advice immediately. There are many options available in the market today. Some involve painting waterproof material on the surface of the roof and at the side of the structure where the beams join.
Another more expensive option is removal of the tiling of the roof and redoing it after performing special waterproofing treatment. The expenses involve will depend on the complexity of the task and the area of the roof
In any rainy day, note that on how many points the leakage of rain water exist from the roof and mark those leakage point with some marker. Than on the dry day find the cause of leakage, i.e. there may be any voids left between tiles or there are some dipression in tiles or leakage with the joints of rain water pipe or with the junction of wall and tile flooring. After locating the leakage points, repair them. For more details see articles in roofing and dampness.