Bad drainage is how foundation problems get started.

Improper Drainage: diagnosed and explained.

Improper drainage is not damage itself; it is the manufacturer of damage. When roof runoff, irrigation, or storm water is allowed to pool against the foundation instead of moving away from it, the soil beneath your home starts changing, and every change is bad. Expansive clay absorbs the water and swells, pushing up on slabs and sideways on walls. When the water source stops, the clay shrinks back, and the repeated cycle rocks the foundation unevenly. Moving water carries fine soil particles away from under footings, quietly removing the support the home was built on. Saturated soil weighs far more than dry soil, spiking the lateral pressure on stem and retaining walls. The visible signs are easy to catch if you look during and after rain: puddles standing against the house hours after the storm, soil splashed onto the stucco, downspouts dumping at the foundation line, planters graded toward the wall, or a crawl space that smells damp and shows standing water. Downstream, the damage wears the usual foundation costumes: cracks, sticking doors, sloping floors, and bowed walls. In Southern California, Arizona, and Nevada, drainage matters more than the rainfall totals suggest, because rain here arrives in intense bursts onto hard dry ground, delivering a year of water in a handful of storms, exactly the loading that overwhelmed grading cannot handle.

For the repair side of this, the foundation repair solutions page lists every method Dalinghaus installs, including the ones that fix problems other than improper drainage.