Crack width alone does not tell you whether concrete is “structural.” ACI guidance starts with cause, extent, movement and function. For a homeowner planning a coating or overlay, the practical question is whether the crack is a stable surface defect—or evidence that the slab/support system is still moving.
Conditions That Deserve Evaluation Before Cosmetic Repair
- Vertical displacement: one side of the crack is higher than the other.
- Ongoing change: crack width, elevation or adjacent joints continue to move.
- Multiple related symptoms: uneven floors, wall/foundation cracks, sticking doors or broader settlement.
- Loss of support: hollow/rocking slab areas, visible voids or recurrent sinking.
- Water or soil movement: repeated washout, piping leaks, erosion or soil loss.
- Critical location/function: structural member, retaining condition, pool shell/coping interface or other condition where failure consequences exceed appearance.
Stable Shrinkage Cracks Are a Different Problem
Concrete commonly develops shrinkage and restraint cracks. ACI distinguishes repair choices according to whether cracking is active or dormant and emphasizes correcting the cause where movement continues. A dormant crack in a sound slab may be routed/filled or repaired as part of a coating system. An active crack may simply reappear through a rigid decorative repair.
A Coating Can Hide the Evidence
A full-flake garage floor or textured pool-deck overlay can make a repaired crack visually disappear. That does not mean the underlying mechanism disappeared. Document crack locations and elevations before the decorative work so future movement is easier to recognize.
Who Should Evaluate It?
The answer depends on the suspected cause and consequence. A coating contractor can identify whether a crack is incompatible with the proposed floor system; a concrete-repair or lifting contractor can evaluate slab support; a plumber/drain specialist may be relevant when leakage is suspected; and significant structural or subsidence concerns may require an engineer, geologist or other qualified professional. The decorative contractor should not be the only source of diagnosis when the repair being sold depends on declaring the slab structurally sound.