Method comparison / poured concrete cracks
Epoxy or polyurethane crack injection?
Choose the repair objective before the resin. Structural bonding and waterstopping are different jobs, and neither material fixes an unaddressed cause of movement or water.
Side-by-side
Compare the job, not the label.
ACI provides independent guidance for structural epoxy injection. The polyurethane conditions below come from a named manufacturer product and stay limited to that product.
Swipe horizontally to compare both materials
| Decision point | Epoxy injection | Polyurethane injection |
|---|---|---|
| Primary job | Bond the faces of a suitable concrete crack as a rigid structural repair. | Stop water through a crack, joint, or void when the selected resin is designed for that condition. |
| Crack condition | ACI RAP-1 calls for the cause to be identified and corrected before injection. Ongoing movement can reopen the concrete beside a rigid repair. | Movement tolerance and water response depend on the actual formulation. The word polyurethane is not a complete specification. |
| Moisture | The named epoxy product reviewed here requires a sound, clean, dry crack and excludes hydrostatic pressure during application. | The named polyurethane product reviewed here reacts in contact with water and is sold for waterstopping. |
| What it does not prove | A rigid bond does not prove the foundation is stable or that drainage has been corrected. | A stopped leak does not prove structural capacity has been restored. |
| Written record | Crack map, cause assessment, product, preparation, ports, pressure, cure conditions, and acceptance criteria. | Water condition, product, activation conditions, injection path, observed take, follow-up sealing, and monitoring plan. |
Before injection
Put six facts in the proposal.
A material name without a condition record is not enough to compare bids or check the completed repair.
- 01
Concrete and crack condition
Identify poured concrete, crack width and direction, displacement, contamination, earlier repairs, and access to both faces where known.
- 02
Movement record
State whether the crack appears dormant, is changing, or has not been monitored. Record repeatable measurements rather than relying on one photograph.
- 03
Water condition
Note dry, damp, intermittent, or active leakage and any hydrostatic pressure, drainage, grading, plumbing, or seasonal pattern.
- 04
Repair objective
Say whether the work is intended to bond concrete, stop water, prepare for another repair, or do more than one of those jobs.
- 05
Named product and preparation
Require the product data sheet, surface and crack preparation, port layout, injection direction, environmental limits, and cure conditions.
- 06
Acceptance and follow-up
Define how completion will be checked, what visible residue or finish work is included, and what happens if movement or leakage returns.
Epoxy boundary
A rigid repair needs a stable explanation.
ACI RAP-1 says the cause of the crack should be determined and corrected before epoxy injection. A rigid bond can be the wrong answer when the crack is still moving, the concrete is unsound, water conditions conflict with the product, or the load path has not been evaluated.
Polyurethane boundary
Water reaction is product-specific.
Sika Injection-101 US is one water-reactive, fast-foaming polyurethane resin intended for waterstopping. Sika also states that some foaming resins are temporary water blocks before another resin is installed. The proposal must identify the actual product and permanent repair sequence.
Regional application note / contractor-owned source
603 starts with the crack pattern, not an injection material.
603 Basement Solutions publishes New Hampshire crack guidance that asks homeowners to record direction, growth, leakage, displacement, and companion symptoms before selecting a repair.
The page does not establish one injection material for every crack. This Guide uses it only as contractor-owned regional context; the material limits above come from the technical sources below.
Technical sources / checked September 11, 2026