On a Paradise Valley tile roof the visible tile is what most homeowners think of as the roof. It isn't. The tile is a wear surface and a shedding layer. The waterproof component is the underlayment beneath it, and that is where most failures in this climate begin.
A standard 30-pound felt under concrete tile begins UV-degrading within a few summers. The tile gaps, the field penetrations, and the heat-loaded west elevation all expose the underlayment to UV cycles that the manufacturer's standard service-life rating doesn't fully account for in this climate. By year ten, what looks like an intact tile roof from the curb has an underlayment beneath it that's brittle and no longer waterproof.
The first monsoon that drives water sideways is the one that reveals the problem — usually as a stain on the ceiling of a master suite. By that point, a partial repair is rarely the answer. The right answer is a synthetic high-temperature underlayment, properly fastened, with the correct detailing at valleys, penetrations, and the heat-loaded west elevation.
We carry this specification on every Paradise Valley tile project. It isn't an upgrade. It's the spec.