How the foothill climate grinds down an Upland roof
The single biggest force on a roof in Upland is the sun. We sit at the base of the San Gabriels where the air is thinner and the exposure is harsh, and that ultraviolet light works on a roof every single clear day of a very long, very dry year. On tile and concrete roofs the tile itself shrugs most of it off, but the felt or synthetic underlayment underneath, the layer that is actually keeping water out, bakes and grows brittle until it cracks and stops sealing. On shingle roofs the UV dries the asphalt, drives off the protective granules, and curls the edges years before a roof in a gentler climate would show the same wear. Around here the roof is aging fastest in the months when nothing is happening to it at all.
Then the weather arrives in concentrated bursts. The Santa Ana winds tear down out of the passes in autumn at speeds that lift and shatter brittle tiles and peel back shingles that the sun has already loosened. The winter rains, when they come, come hard and fast, testing every flashing detail and every tired underlayment seam at once after months of drought. And the dry brush that surrounds the foothill neighborhoods turns the roof into the front line in fire season, where a single ember in the wrong gap can do what no rainstorm ever would. We inspect with all of that in mind, because a roof that looks fine in the June sun can have three different vulnerabilities waiting for three different parts of the year.