Two distinct chemistries, one for each crack type. Polyurethane expands when water touches it, sealing active leaks from the inside. Epoxy bonds dormant cracks into monolithic strength. We diagnose the crack first, then inject the right Sika product to full depth. No guessing.
The concrete crack you're looking at tells a story. Is water flowing through it right now, or is it dry and stable? That single question determines which Sika product will work. Polyurethane is a water-reactive chemistry; it expands when moisture hits it, filling the crack and bonding to wet surfaces. Epoxy is a structural adhesive; it hardens into a permanent bond between the two sides of a dormant crack, restoring load-carrying capacity.
Mixing them up wastes money and fails the repair. Epoxy cannot displace water, so it fails in active leaks. Polyurethane in a dry structural crack leaves the two sides unglued. We assess each crack for activity, moisture, and structural role before selecting the product. The right chemistry makes the difference between a repair that holds and one that fails in the next freeze cycle.
See our broader Sika waterproofing work for larger moisture control strategies. For residential foundation cracks specifically, review foundation crack repair options. We also offer Sika repair mortars for surface finishing after injection.
Recent work
The injection sequence
How Crack Injection Gets Done in Portland
Assess the crack condition
We examine the crack for signs of water movement, measure its width and depth, and determine whether it's structural or cosmetic. This assessment drives the product choice.
Prepare the surface and ports
The crack is cleaned, injection ports are installed at calculated spacing, and the surface between ports is sealed with paste to contain the material during injection.
Inject under controlled pressure
Sika polyurethane or epoxy is pumped through each port in sequence at the pressure specified for that product, ensuring the material reaches the full depth of the crack.
Cure and finish
The material cures (polyurethane fast, epoxy over several days), ports are removed, the surface is sealed, and the repair is verified before handoff.
For active leaks
Polyurethane Injection Stops Water Now
A basement wall leaking water cannot wait for epoxy to cure. Polyurethane reacts with the water itself, expanding to fill the crack and creating a seal from the inside. The water triggers the reaction, the material expands, and the leak stops during injection. This is the only chemistry that works in wet conditions.
Polyurethane injection is fast (cure in hours), and the repair holds through freeze-thaw cycles because the expanded material is flexible and bonds to wet concrete. We use it for any active seepage, basement leaks, or cracks where water is present at the time of injection. See our Sika waterproofing systems for larger-scale moisture control. For foundation leaks, also review basement waterproofing options.
Polyurethane vs epoxy, active leaks, port spacing and structural restoration.
Polyurethane for active wet cracks (it reacts with water to expand and bond), epoxy for dormant dry cracks that need structural restoration (it bonds the crack sides permanently). The wrong chemistry fails immediately.
Yes, polyurethane is specifically designed for this. The water in the crack triggers the polyurethane reaction, the material expands to fill the crack, and the leak stops.
Yes, with epoxy. Properly injected epoxy restores the two sides of the crack to monolithic strength. The crack itself becomes structurally stronger than the surrounding concrete in many cases.
Based on crack width, depth, and the chosen chemistry's flow characteristics. Sika specifies port spacing per product; we follow the spec so material reaches full-depth without gaps.
Most residential crack injections are a single-visit job, a few hours from port install through cure. Large structural projects with many cracks stretch over days. The schedule is in the quote.
Polyurethane injection on an actively leaking basement crack. Water stopped during injection, dry for two years since. The right chemistry made the difference.
Q. Y5
Property Owner, Portland
★★★★★
Epoxy injection for structural restoration on a foundation crack. Test cores after cure showed the crack zone stronger than surrounding concrete. Real structural repair.
Y. Y5
Engineer, Vancouver
★★★★★
Multiple cracks across a structure, each classified properly and injected with the right chemistry. The discipline of product-per-crack-condition is rare and showed in the result.
Z. Y5
GC, Hillsboro
★★★★★
They diagnosed an injection that another contractor had failed on. Used the right Sika polyurethane this time; held through three winters. Crack chemistry matters.
X. Y5
Builder, Gresham
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Concrete Guides & Articles
Practical reading on planning, finishes and caring for concrete in Portland.
Describe the crack (active or dormant, wet or dry, structural or cosmetic), and we will recommend the matched Sika product and provide a written estimate.
