Crack Repair Preparation, Process, and Care

Before any repair, we assess the slab for moisture, identify every crack, spall, and hole, and determine what each defect needs. A static crack gets a rigid filler; a moving crack gets a flexible sealant; a spall gets a patch. The assessment tells us what the slab needs before we quote the repair — because a repair that's quoted without assessing the crack type is a repair that's quoted blind.

We also assess the slab's overall soundness. A slab with surface cracks but sound structure is a candidate for repair and coating; a slab with structural failure may need more than repair. We tell you honestly what the slab needs, because we don't sell repairs that won't last.

A crack is routed — opened with a grinder to sound material — so the repair material has a clean, sound surface to bond to. A crack that's filled without routing is a crack that's filled over contaminated material, and the repair won't bond. The routing also gives the repair material a consistent depth, which matters for the filler's performance.

The crack is then cleaned — vacuumed and wiped — so there's no dust or debris in the routed channel. A clean crack is a bondable crack; a dirty crack is a crack where the filler sits on top of the dust. The cleaning is the step that makes the repair bond, and it's the step that's most often skipped by a repair that doesn't last.

The routed crack is filled with the repair material matched to the crack type — rigid for static, flexible for moving. The filler is pressed into the channel so it bonds to the sound material on each side. A spall or a hole is cleaned out and filled with a patch material, which is then leveled to the surrounding slab.

The fill is the repair. A properly filled crack, with the right material and a sound substrate, gives the coating a stable surface to bridge. A poorly filled crack — wrong material, contaminated channel, or under-filled — is a crack that telegraphs through the coating. The fill is where the repair succeeds or fails.

The repair is leveled to the surrounding slab so the coating bridges a smooth, sound surface. A repair that's proud — higher than the slab — is a bump under the coating; a repair that's under-filled is a dip. The leveling is the step that makes the repair invisible under a solid color coating and sound under any coating.

After the repair is leveled, the slab is diamond-ground to profile the surface for the coating. See our diamond concrete preparation and polishing for the full prep scope. The grinding removes the laitance and the contaminants and gives the coating a profiled surface to bond to — and the repair, now sound and level, is part of that surface.

Once the slab is repaired and coated, the care routine is the coating's care routine — sweep, mop with a neutral cleaner, clean spills promptly. The repair itself doesn't need separate care; it's part of the slab, and the coating protects it. See our coated floor renovation and maintenance for the coating's care scope.

What to watch for: if a repaired crack telegraphs through the coating — a hairline line appears where the crack was — it may mean the crack is moving and the repair needs attention. A static crack that's properly repaired won't telegraph; a moving crack that's telegraphing may need a flexible repair or a maintenance touch-up. We can assess the telegraphing and tell you whether it's cosmetic or structural.