The way a roof actually wears out in this climate
If you want to understand why a Lake Forest roof eventually fails, follow the water and follow the heat, because between them they do nearly all the damage here. The heat comes first and works the longest. We sit far enough inland that the summers run hot and the ultraviolet load is heavy, and that radiation is hard on roofing in two different ways depending on what is up top. On a shingle roof it dries the asphalt and carries off the protective granules a little more each season. On a tile roof the tile itself barely notices the sun, but the heat builds up in the attic and the air space beneath the tile and slowly cooks the waterproof membrane underneath, the layer doing the real work, until it loses its flexibility and begins to crack.
Then the water arrives, and it does not arrive gently. After a long dry stretch the first real storm of the season dumps a lot of rain in a short window onto a roof full of the small openings the summer opened up. The wind plays its part in between, the dry Santa Anas that drop out of the canyons in the fall, lifting anything whose seal has dried, working under any tile that has slipped a fastener, and carrying grit and debris off the higher slopes onto the lower ones. None of these forces is dramatic on its own. It is the sequence, heat that weakens, wind that pries, and a sudden soaking that finds the gaps, that wears a roof out here, and it is the sequence we build every repair and every replacement to survive.