What the east valley climate asks of a La Verne roof
The force that does the most to a La Verne roof is simply the sun. The city sits where the valley meets the foothills, the summer runs long and the sky stays clear for weeks at a stretch, and that steady ultraviolet load goes to work on roofing material every cloudless day whether anyone notices or not. On the tile roofs that cover most of the town the tile itself barely flinches, but the underlayment tucked beneath it, the layer actually holding water out, slowly grows stiff and brittle until it splits and stops sealing. On the shingle roofs that turn up here and there the same sun scours away the protective granules, dries out the asphalt, and lifts the edges well ahead of the schedule the warranty assumed. The uncomfortable part is that a La Verne roof loses most of its ground during the long, pleasant-looking stretches when nothing seems to be happening to it at all.
Once the sun has done its slow work, the rest of the weather shows up in bursts and goes hunting for the weak points the heat created. The autumn winds come down off the slope behind the city and locate every tile the summer turned fragile, snapping and sliding them and prying at any shingle that has already loosened its grip. The winter rains land brief and heavy, testing every flashing joint and tired seam of underlayment in a single afternoon after months of bone-dry weather. And on the upper streets where homes sit closer to the dry brush, the roof becomes part of the question of fire every year. We inspect with all of that in view at once, because a La Verne roof that looks untouched in the June light can be carrying three separate vulnerabilities waiting on three separate seasons to expose them.