Sloping & Uneven Floors: Is It Your Slab?

A floor that pitches to one side or feels “off” underfoot is one of the most direct signs that part of your slab has dropped. Here’s how to confirm it and what the fix looks like.

The marble test

Set a marble on the floor; if it consistently rolls one direction across multiple rooms, you likely have differential settlement, not just a worn subfloor. A free elevation survey measures the exact drop.

How much slope matters

Many engineers flag movement beyond roughly 1 inch over 20 feet. We measure to ±0.01 in. (1/64 in.) and show you where the low points are before recommending foundation leveling.

The repair

Steel piers driven beneath the settled area let us lift the slab back toward level and lock it there. Homeowners in Round Rock and Georgetown see doors and floors recover together.

When Your Floors Tilt: Reading the Story Written in Your Slab

A marble rolled across a Central Texas living room floor that gains speed toward one corner is not telling you about poor craftsmanship — it is telling you about soil. The Blackland Prairie clays that blanket the San Antonio–Austin corridor have plasticity indices routinely measured between 40 and 60, meaning a single soil column can swell several inches when wet and shrink back nearly as far when dry. When that movement is uneven — greater beneath one beam pocket than another, or concentrated along a shaded north wall versus a sun-baked south slab edge — the concrete above it tilts. Understanding that mechanism is the first step toward deciding whether a slope is cosmetic, structural, or somewhere in between.

Concrete slabs behave as relatively rigid plates resting on soil. When the support beneath a portion of the slab drops away — through clay shrinkage during drought, through erosion along a poorly graded yard, or through a perimeter beam losing its bearing depth in the active zone — the slab does not uniformly follow. Instead, it bridges the void until the span exceeds what the reinforcing steel and slab thickness can carry, then cracks and rotates. The result is not a bowl-shaped depression but an angular tilt, often most visible across open-plan spaces. A slope of 1 inch over 10 feet is frequently noticeable to occupants; slopes approaching 2 inches or more per 10 feet are generally considered a threshold requiring engineering evaluation, though comfort thresholds and structural thresholds are not the same thing.

Not every sloping floor originates from foundation movement. Hardwood or engineered-wood flooring installed over a slab that was never laser-leveled can introduce apparent slopes of a quarter inch or more. Settlement of a heavy partition wall, a post-tensioned cable that lost tension in one zone, or even a floor joist issue in a pier-and-beam section of the same home can create localized dips. This is why a ±0.01-in. elevation survey — measuring actual concrete elevations at a grid of points across the structure — is the only reliable way to distinguish between a slab problem, a finish-floor problem, and a framing problem. Without that data, any repair discussion is speculation.

When the elevation survey confirms that the slab itself has moved, the engineering question shifts to where the soil support has degraded and how deep stable bearing stratum lies. West of the Balcones Escarpment, Edwards limestone often appears within a few feet of the surface, and slab repairs can involve relatively short steel pier segments. In the heavier clay zones to the east, the active soil zone — the depth through which seasonal moisture fluctuations cause meaningful volume change — can extend 10 to 15 feet or deeper depending on local drainage patterns and vegetation. Galvanized steel piers driven hydraulically through that entire active zone, down to the competent stratum below, remove the repaired section of foundation from the shrink-swell cycle entirely. Concrete pressed piers that terminate within the active zone remain subject to further movement as soil conditions change season to season.

• Confirm the floor slope is in the slab, not the finish material. Tap the floor surface and probe for hollow spots; an uneven subfloor layer can produce a convincing slope without any slab movement at all.
• Look for corroborating symptoms. Drywall cracks running at 45 degrees from window corners, doors that bind or gap at the latch side, and visible gaps between baseboard and floor along one wall all suggest genuine slab rotation rather than a cosmetic floor issue.
• Grade the yard to direct water away. The general standard is 6 inches of drop within the first 10 feet from the foundation perimeter; flat or negative grades allow rain to pool against the beam, driving moisture differential between the slab edge and interior.
• Water the foundation perimeter during dry periods. Soaker hoses placed 18 to 24 inches from the foundation maintain more consistent soil moisture and reduce the differential shrinkage that produces edge settlement.
• Obtain a written engineer-backed plan before any repair begins. The number of piers, their locations, and the lift sequence all affect whether the slab recovers its elevation or sustains additional cracking during the repair process.

The repair process for a settled slab section involves hydraulically driving steel piers at calculated spacing along the affected beam, then using the pier heads and hydraulic jacks simultaneously to return the slab toward its original elevation in a controlled lift. Simultaneous lifting matters: raising one section ahead of adjacent sections concentrates stress at the transition and can propagate new cracks into previously undamaged areas. Once the structure reaches the target elevation — verified against the original survey data — the piers are locked and the system transfers the dead load of the house permanently to the bearing stratum below. Because that stratum is below the active zone, the repaired foundation section is no longer subject to the seasonal tilting cycle. A lifetime transferable warranty reflects that permanence: the fix travels with the house, not the homeowner, which matters when the time comes to sell.

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