Foundation Footing Repair: What a Footing Is and How It's Fixed

Foundation footing repair is one of the most misunderstood phrases in the trade, because the footing itself is rarely the thing that needs repairing — the soil beneath it is. A footing is the widened concrete base at the bottom of your foundation that spreads the building's load across the ground. When it "fails," it has almost always settled into soil that moved, and the engineered fix is to underpin the footing with piers that reach stable strata — not to patch the concrete. This page explains what a footing actually is, how it differs from the slab and stem wall, how footings fail, and why "footing repair" and underpinning are, in practice, the same job.

What a Footing Is (and How It Differs From the Slab/Stem Wall)

A footing is the load-spreading base of a foundation. The weight of a house arrives at the ground as concentrated lines and points — down through walls, columns, and the edges of a slab. Soil can't carry that concentration directly without sinking, so the footing flares out beneath the load to spread it over a wider area. The wider the foot, the lower the pressure on any square inch of soil. That's the footing's entire structural job: take a heavy, concentrated load and hand it to the soil gently enough that the soil can hold it.

It helps to separate three terms homeowners often blur together:

• The footing is the spread base at the very bottom, in direct contact with the soil. It's what carries the building's load into the ground.
• The stem wall is the short wall that rises from the footing up to floor level, common in pier-and-beam and basement homes. It transfers the wall load down to the footing. The footing is wider than the stem wall sitting on it — that's the spread.
• The slab in a slab-on-grade home is the floor itself; its perimeter and interior load lines are usually thickened into integral footings (a thickened edge or grade beam) that do the same spreading job.

So "the foundation" is the whole below-grade system, and "the footing" is one specific part of it — the base that meets the soil. When a quote says "foundation footing repair," the problem and the fix both live at that base, in the dirt below it.

How Footings Fail

A footing rarely fails because the concrete is weak. It fails because the soil it bears on stops holding still. The common mechanisms:

• Differential soil movement (the dominant cause in San Antonio). Expansive clay swells when it takes on moisture and shrinks when it dries out. As the soil under one part of a footing rises or drops relative to another, the footing — and the wall above it — moves with it. The American Society of Civil Engineers estimates one in four U.S. homes has some damage caused by expansive soils. This is the local story; see expansive clay soil for why South-Central Texas is so prone to it.
• Undersized or old footings. Footings poured before modern code, footings sized for a lighter original structure, or footings on poorly compacted fill may simply be too small or too shallow to spread today's load over soil that can hold it. They were never wrong for their day; they're under-built for the conditions now imposed on them.
• Erosion and washout. Water that channels under a footing — from poor grading, a plumbing leak, or downspouts dumping at the perimeter — can carry away the soil that supports it, leaving a void the footing drops into.
• Frost heave (a cold-climate problem, not a San Antonio one). In northern states, moisture in shallow soil freezes, expands, and lifts a footing that wasn't placed below the frost line. This is precisely the failure IRC §R403.1.4 guards against by tying footing depth to the local frost line. San Antonio's frost penetration is minimal, so frost-heave footing failure is largely a non-SA, northern issue — worth knowing, but not the regional concern here.

The through-line: in every case except a genuinely crushed footing, the footing moved because the ground moved. That is the single fact that determines how it gets fixed.

What "Footing Repair" Actually Means (Underpinning the Footing)

Here is the part most marketing pages won't say plainly: when a footing has settled, you don't repair the footing — you underpin it. Underpinning is installing new deep supports beneath the existing footing to transfer the building's load past the unstable surface soil down to competent strata or bedrock. The footing stays where it is; the piers take over the bearing job the soil could no longer do.

In San Antonio's expansive-clay belt, the soil that swells and shrinks — the active zone — extends from roughly 8 to 15 feet below the surface. A pier's job is to reach below that active zone to soil that doesn't move with the seasons. Two systems do this for residential footings:

• Steel push piers — galvanized steel pipe driven beneath the footing to refusal, using the building's own weight as the reaction force. Best under heavier, settled homes over a reachable bearing layer.
• Helical piers — screw-plated shafts torqued in, with capacity verified by installation torque. Best under lighter structures, additions, and soils where a push pier can't develop enough reaction.

Which one your footing needs is a soil-and-structure decision an engineer makes, not a product a contractor picks. The mechanics of each system, and the full menu of deep-support methods, live on the underpinning hub and the methods overview — this page deliberately doesn't re-explain pier mechanics, because "footing repair" is really the why, and underpinning is the how.

Cost & Code (IRC §R403 Context)

Because footing repair is underpinning, it's priced like underpinning, and the code that governs it is the residential-foundation chapter.

On cost, the planning numbers below are 2026 ranges, not quotes. The variable that moves the bill most is how much of the footing actually needs support — which is exactly what an engineer's elevation survey defines.

For national context, This Old House puts the 2026 average foundation repair project near $5,179, and HomeAdvisor's 2025 range is $2,225–$8,133 — figures that span everything from crack sealing to full underpinning, so a structural footing job that requires piers sits toward the upper end.

On code, footings are governed by the International Residential Code's foundation chapter, and an engineer's design should reference it by section:

• IRC §R403.1.4 requires exterior footings to be placed not less than 12 inches below the undisturbed ground surface and below the local frost line shown in the code's design tables. This is the rule that keeps footings out of the shallow soil that moves with weather — and the reason frost heave is a northern problem, where that frost line sits deep.
• IRC §R403.1.8 directs that foundations on expansive soils be designed per IBC §1808.6. In San Antonio this, not frost, is the governing condition: footings here are engineered for clay that swells and shrinks, which is why reaching below the active zone matters more than frost depth.
• IRC §R403.3 permits frost-protected shallow foundations for heated buildings as an alternative in cold climates — again, a cold-region provision with little local relevance.
• IBC §1810 (Deep Foundations) is the chapter that governs the piers used to underpin an existing footing. A quote that claims to be "code compliant" without citing these sections is marketing copy, not an engineering statement.

FAQ Note

The FAQ below covers what San Antonio homeowners ask most after a first contractor visit — what a footing is, footing versus foundation, whether a footing can be repaired without replacement, why patching fails, code depth, and the regional irrelevance of frost. For a structured second opinion before signing, start with an engineer's report or compare the deep-support methods on the methods hub.

Get Matched With a Vetted San Antonio Footing-Repair Specialist

If your independent engineer has determined your footing needs underpinning — or a contractor proposed "footing repair" and you want a PE-led second opinion before committing — we'll match you with a vetted San Antonio foundation specialist who can install to the engineer's design. The match is free, the quote is no-obligation, and we don't take a fee from you. We screen for IBC §1810 compliance, current ESR-listed pier systems, sealed-engineer design that names the affected stretch of footing, per-pier documentation, and a clean Bexar County permit record. If a quote proposes patching a footing without addressing the soil, or underpins more of it than the engineering calls for, we'll tell you. That's the only way an editorial matching service should work.