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Problems & Signs

Cracks in Your Slab Foundation: When to Worry

Almost every concrete slab cracks a little. The question is whether you’re looking at harmless shrinkage or a structural crack from foundation movement.

Shrinkage cracks

Thin, shallow cracks that appear as concrete cures are normal and usually stable. They rarely affect structure on their own.

TopsoilExpansive clay — swells & shrinksLoad-bearing stratum
FIG · Where slab cracks form over moving clayN.T.S.

Structural cracks

Cracks wider than a quarter inch, with vertical displacement (one side higher), or that run with floor slope and wall cracks signal that the slab is bending over moving soil — a job for slab foundation repair.

MonitorLikelyAct now
Reading: Displaced edges — act
INFOGRAPHIC · Severity scaleIndicative

Get it measured

Vertical offset across a slab crack is the red flag. A free elevation survey confirms whether the slab has actually dropped, common in Buda and San Marcos.

Key takeaways
  • Thin curing cracks are usually harmless.
  • Width over a quarter inch or vertical offset is structural.
  • Elevation measurement confirms real movement.
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Frequently asked

Can a cracked slab be repaired without replacement?
Yes — steel-pier stabilization re-levels and supports the existing slab. Replacement is rarely needed.
Does sealing a slab crack fix it?
Sealing keeps water out but doesn’t stop movement. If the slab is settling, stabilize first.
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