24H Mold Inspection of San Bernardino

San Bernardino grew as a railroad town, and its Santa Fe Depot, opened on July 15, 1918, was the largest train station west of the Mississippi when it was built. Route 66 ran through the city, and Richard and Maurice McDonald started their restaurant here in 1940. Downtown's older commercial blocks are masonry buildings with flat roofs behind parapets, many vacant or converted over the years, alongside early-twentieth-century homes on the surrounding streets. Clogged roof drains, failing parapet flashing, aging supply plumbing, and buildings left empty long enough for small leaks to become large ones are the recurring risks here.

Much of downtown and the valley floor sits over the Bunker Hill groundwater basin — formerly swampy land with a documented history of artesian springs and flowing wells, where the water table can sit unusually close to the surface. In wet years that shallow groundwater presses up into slabs, crawl spaces, and older foundations, so moisture here often rises from below rather than entering from a leak overhead. Slabs poured in the postwar decades rarely included a vapor barrier, and the signs are damp carpet pad, lifting floor tile, and white mineral deposits along the slab edge with no plumbing failure anywhere in sight.

The Westside, the North End, and the central tracts are dominated by 1950s and 1960s single-story stucco homes on slabs, many of them rentals through several changes of ownership with maintenance that varied along the way. The recurring moisture sources are aging galvanized or copper supply lines leaking inside walls or under the slab, cast-iron drains cracking beneath bathrooms, original ductwork sweating in hot attics, roofs re-covered over older layers, and evaporative coolers leaking at their roof curbs. Garage conversions on unsealed slabs and unpermitted additions hide further moisture paths behind fresh paint.

The northern neighborhoods — Arrowhead, Del Rosa, and Verdemont — climb the alluvial fans toward the mountains beneath the Arrowhead landmark, along the base where the San Andreas Fault runs. In October 2003 the Old Fire burned the slopes above and destroyed hundreds of homes along the city's northern edge, and on Christmas Day an intense storm set off debris flows across the burn areas that killed 16 people near San Bernardino. Burned slopes shed water and sediment far faster for years afterward, pushing runoff against uphill walls, garage slabs, and retaining walls, while earthquakes open cracks that let it in.

North and west of the core, semi-rural Muscoy and Arrowhead Farms sit on large lots with a mix of older traditional houses and manufactured homes, many on septic systems, with horse property, outbuildings, and long unpaved driveways. Manufactured homes carry plumbing inside an underbelly wrap that hides leaks against the floor decking, and skirting traps humid air beneath the floor. Older traditional houses here often have additions built in stages and roofs patched over time. Wind out of the passes lifts roofing and drives dust into vents and cooler housings, and runoff across open land collects against foundations after storms.