Riviera estates were built in the plaster-and-lath era, with thick walls, wood framing, red clay-tile roofs, and original clay sewer laterals. That construction is beautiful and slow to dry. Plaster holds water long after the surface looks fine, so we map moisture with meters and thermal cameras instead of guessing.
Tile roofs on the older homes crack and slip over the decades, and a single displaced tile lets winter rain into the attic and down an interior wall. The hillside setting also means many homes have stepped foundations and tucked-under rooms where water collects at the lowest point and lingers. Garages and wine storage cut into the slope are usually the lowest point in the house, so they take on runoff first and hold it longest.