Best Concrete Crack Filler for Each Job
There's no single best concrete crack filler. The right product depends on how wide the crack is, whether it moves, and whether it's flat or vertical. Use this guide to pick the right type.
Quick picks by job:
Driveway or patio crack under 1/2": self-leveling polyurethane sealant.
Crack in a wall or step: non-sag polyurethane caulk.
Leaking basement wall crack: polyurethane injection kit.
Structural bond on a dry crack: epoxy.
Wide, shallow damage: vinyl concrete patch or repair mortar.
Concrete crack filler types compared
| Type | Crack width | Flexible? | Pros | Cons |
|---|---|---|---|---|
| Self-leveling polyurethane | Up to ~1/2" (with backer rod) | Yes | Flows into cracks on flat surfaces, weatherproof | Runs out on slopes. Needs a dry crack. |
| Non-sag polyurethane caulk | Up to ~1/2" | Yes | Stays put on vertical surfaces | Needs tooling for a neat finish |
| Silicone-based concrete sealant | Small | Yes | UV-resistant, fast curing | Most can't be painted |
| Epoxy filler or injection | Hairline to ~1/4" | No | Very strong bond, structural | Cracks again if the concrete moves. Needs dry conditions. |
| Polyurethane injection foam | Hairline to ~1/4" through walls | Yes | Stops leaks, works on damp cracks | Not structural |
| Vinyl or latex patch | Wide, shallow | No | Trowelable, can feather to thin edges | Not for moving cracks |
| Concrete repair mortar | Large and deep | No | Strong, rebuilds broken edges | More work, rigid |
How to choose
- Does the crack move? Outdoor cracks and cracks that open and close with the seasons need a flexible sealant. Rigid fillers will crack again.
- How wide and deep? Use backer rod for anything deeper than about 1/2". Use patch or mortar for wide, shallow damage.
- Flat or vertical? Self-leveling products are for flat surfaces only.
- Wet or dry? Most fillers need a dry crack. Polyurethane injection is the exception.
- Will it be painted or coated? Check the label. Many silicones can't be painted, and garage-floor coatings may require a matching epoxy filler.
Common mistakes
- Filling dirty or wet cracks, so the filler doesn't bond
- Using rigid filler on a crack that moves
- Filling deep cracks without backer rod, which wastes material and makes for a weaker joint
- Sealing a structural crack in a foundation instead of diagnosing it. Check it first.
Ready to apply it? Follow our concrete crack repair or driveway crack repair steps.
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