Footing

Every wall, column, and grade beam sends its load down into the ground, and something has to spread that weight across enough soil to carry it. That job belongs to the footing, a wider slab or strip of concrete poured at the base of the structure above it. Without that spread, the weight would punch into the dirt and the home would settle, crack, or tilt.

Footing size comes from two numbers: how much load is pressing down, and how much weight the soil can safely hold (its bearing capacity). The International Residential Code sets minimum footing widths and depths in Chapter 4, and a soils report can require more. Heavier loads or weaker soil mean a wider, deeper footing. The footing also has to reach below any zone that moves with frost or moisture, though in the low desert frost depth is shallow and the bigger concern is expansive clay.

For example, a two-story custom home in Cave Creek puts more load on its perimeter than a single-story ranch, so its continuous wall footings are wider, and an interior steel post may sit on its own thickened pad footing sized for that point load. The structural engineer calculates each one.

A footing is not the same as a stem wall, which is the short wall that rises from the footing to support the floor above, or a grade beam, which spans between supports. The footing is the part that actually contacts and loads the soil. On Arizona's expansive soils, footing design ties directly to the geotechnical report, because the same load needs more support on swelling clay than on firm caliche. We pour footings to the engineer's stamped sizes, never to a generic detail.