Drainage, Moisture, and Foundation Performance Building science and geotechnical references consistently identify water management as a key factor in foundation performance, especially in regions with expansive soils like Los Angeles County. When water accumulates around a foundation, it can increase pore water pressures, soften supporting soils, or cause expansive clays to swell, leading to heave, settlement, and cracking. Local building codes and best-practice guides require that finished grades slope away from structures and that roof runoff be collected and discharged away from foundations via gutters and downspouts. Inadequate surface drainage—such as flat or negative slopes, downspouts discharging at the base of walls, or excessive irrigation near the house—is frequently cited in inspection reports as a contributing cause of foundation movement. In areas with known drainage or groundwater issues, engineers and contractors often recommend systems such as French drains, area drains, and sump pumps to intercept and redirect water. Civil engineering and waterproofing standards explain that these subsurface systems must be properly sized, sloped, and discharged to an appropriate location to be effective. For hillside properties in Los Angeles, local hillside ordinances emphasize managing surface runoff and subsurface seepage to reduce slope instability and foundation distress. Moisture management also includes controlling landscaping and irrigation. Extension and building science publications advise maintaining consistent soil moisture levels by avoiding overwatering near foundations and using drought-tolerant plantings that require less frequent irrigation. They caution that abrupt changes in moisture—such as eliminating irrigation entirely after long periods of overwatering—can also cause soil shrinkage and movement. Effective foundation repair plans in Los Angeles often incorporate both structural measures and improved drainage, recognizing that ignoring water management increases the risk of recurrence of foundation issues over time. Ending with this sentence for completeness.