Filled Foundation Crack Reopens Within One Year: Active Movement vs. Improper Injection Decision Tree

Why this matters

A crack that reopens after injection is one of the most damaging warranty situations in foundation repair. It erodes customer confidence, triggers callback costs, and can mask a structural problem that needs more than a fill. Distinguishing active movement from improper injection requires a disciplined comparison against original documentation - the field crew's first job at every injection is to create that documentation so callbacks can be resolved without guesswork.

How to confirm the crack has actually reopened

Before diagnosing root cause, confirm the failure mode. A crack can appear to reopen for three reasons: the fill actually cracked again, the surface paint or sealer cracked without the fill cracking, or a parallel hairline formed adjacent to the original repair.

Steps:

1. Probe the crack with a utility knife blade. If the blade enters the fill material, the fill cracked or was never complete.
2. Compare crack width at the same port locations documented at time of service. Width increase of more than 0.005 inches (visible gap, not a hairline) signals movement.
3. Check whether the crack path follows the original exactly. A crack that jogs to a new path is almost certainly new movement, not injection failure.

If the blade cannot enter the fill and width is unchanged, the crack has not reopened - document this finding and educate the customer.

Branch 1: Active structural movement

Active movement means a force acting on the wall or slab has continued after injection. The injection stopped the water but not the cause.

Indicators of active movement:

• Crack width is measurably wider than original documentation
• New parallel cracks have appeared within 6 inches of the repaired crack
• Stair-step cracking has propagated since service
• Interior doors or windows that were binding before service are binding more severely now
• The crack path shifted direction compared to original photos

Common ongoing forces:

• Soil settlement under the footing (crack reopens at the top, closes at bottom, or vice versa depending on direction of settlement)
• Lateral soil pressure (crack is wider at the interior face, or wall shows slight bow)
• Seasonal heave from expansive soil (crack cycles with season - open in dry months, closed in wet months)
• Surcharge from a new load added after service (driveway extension, deck footing, stored materials against the exterior wall)

Decision point - active movement requires:

• Root cause identification from the list above
• A structural solution appropriate to the force type
• Customer explanation that the injection was correctly performed but the underlying cause was still active at time of service

Branch 2: Improper injection

Improper injection means the fill material did not fully occupy the crack at time of service. The fill is present at the surface but the crack interior was not fully filled.

Indicators of incomplete injection:

• Crack reopens at the same width as originally documented (no change in width - no movement occurred)
• No new parallel cracks have appeared
• Probing reveals the fill is hollow or the surface seal bridged without penetrating
• Injection ports were spaced more than 10 inches apart for a crack narrower than 0.02 inches (ports too far apart to ensure coverage at that width)

Common injection failure modes:

• Surface sealer applied before fill reached the port (pressure relief path was blocked, fill spread laterally rather than filling the crack depth)
• Injection pressure too low to push material past an obstruction (debris, previous repair material, aggregate)
• Wrong material selected: polyurethane foam is flexible and appropriate for non-structural water-stopping only; it will compress and re-gap under any structural load; structural epoxy or rigid polyurethane is required where load transfer across the crack is needed
• Ambient temperature below the material's minimum application temperature at time of injection, causing premature gelling before full penetration

Decision point - incomplete injection requires:

• Core drilling a test hole through the repair to confirm fill depth
• Re-injection under proper conditions with documented port placement and injection pressure
• Material review to confirm the correct product was selected for the structural requirement

Reading original documentation

The single most important factor in resolving a reopened-crack callback is whether the service crew documented crack width, location, and photos at time of service. Without this:

• Width change cannot be established
• Movement vs. no movement cannot be distinguished
• Liability for any pre-existing cracks is unclear

Every injection job should carry: photo of each crack before cleaning, ruler or crack gauge measurement at three points per crack, injection port locations marked on a sketch, material product and lot number, ambient and surface temperature at time of injection.

If documentation is missing, treat the callback conservatively: assume movement may be active, perform structural assessment before re-injecting.

When to re-inject vs. when to escalate

Re-injection is appropriate when:

• Incomplete fill is confirmed and no active movement is present
• Structural stabilization was completed and one full seasonal cycle has elapsed with no new width change

Escalate to structural assessment when:

• Width increase is confirmed
• New parallel cracks appeared
• Customer reports new door or window binding since service
• Crack is in a load-bearing wall and width change is more than 0.02 inches

References

• Portland Cement Association, "Guide to Concrete Crack Repair," PCA Publication IS234
• International Concrete Repair Institute, "Selecting and Specifying Concrete Surface Preparation for Sealers, Coatings, Polymer Overlays, and Concrete Repair," Guideline No. 03732
• ACI 224.1R, "Causes, Evaluation, and Repair of Cracks in Concrete Structures," American Concrete Institute