When to Call a Contractor
A severity 3 crack has crossed the threshold where DIY repair is appropriate. It may not be a structural emergency, but attempting to fill it yourself risks masking an active problem and spending money on a repair that will fail. This is the point to call a licensed concrete contractor for an assessment.
Professional Repair Triggers
Any of the following conditions warrants a contractor call. You do not need to have all of them — one is enough.
Crack width approaching or exceeding 1/4 inch
The 1/4-inch threshold is the industry standard dividing line between cosmetic and professionally significant cracking. At this width, simple crack filler is unlikely to be a durable solution without professional surface preparation.
Minor displacement between crack edges
Any vertical displacement (one side slightly higher than the other) indicates differential movement. While minor displacement may not be a structural emergency, it requires professional assessment to determine whether the movement is active or arrested.
Crack covering a large area or multiple connected cracks
Isolated cracks are easier to assess. A network of connected cracks across a large area of slab suggests a systemic issue — poor mix design, widespread settlement, or ASR — that needs professional diagnosis before repair.
Crack in or near a load-bearing element
Even a crack that looks cosmetic is automatically severity 3 or higher if it's in a foundation wall, structural column, beam, or load-bearing slab. Location changes the risk profile entirely.
Active crack that is visibly growing
If you can see the crack has widened since you first noticed it, the underlying cause is still active. DIY repair of an active crack is pointless — the filler will fail as the crack continues to move.
What to Tell the Contractor
Before the contractor visit, document the crack: photograph it with something for scale (a coin, a ruler), note when you first saw it, and note whether it has visibly changed. Tell the contractor:
- —When the concrete was poured (if known)
- —Whether the crack has grown since you first noticed it
- —Whether there is any water or drainage issue near the crack
- —Whether the crack is in a location with vehicles or heavy equipment
- —What the climate is like — freeze-thaw cycles, high summer heat
Repair vs. Replacement
A contractor assessing a severity 3 crack will typically recommend one of three paths:
Repair in place
Epoxy injection, crack stitching, or overlay systems. Appropriate when the slab is otherwise sound and the crack is static.
Partial replacement
Cut out and repour a section. Used when the damaged area is localized and the surrounding concrete is in good condition.
Full replacement
Remove and repour the entire slab. Recommended when damage is widespread or the underlying cause (soil, drainage) requires the slab to be removed to address it.
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