Sika crack injection chemistry covers both ends of the repair spectrum: polyurethane that expands on contact with water for active wet cracks, and epoxy that structurally bonds the two sides of a dormant crack for permanent repair. Portland Concrete picks the right Sika product for the actual crack condition, then injects to full depth so the repair holds. Every assessment is free.
Crack injection chemistry is not interchangeable. Polyurethane reacts with water and expands inside the crack, which makes it the right answer for active leaks where water is present at the time of injection. Epoxy is structural; it bonds the two sides of a dry crack permanently, restoring the slab to monolithic strength. Using polyurethane for structural restoration wastes the product; using epoxy in an active leak fails on injection.
We classify each crack first (active or dormant, wet or dry, structural or non-structural), then pick the matched Sika product. Sika offers both chemistries in injection-grade formulations with the port hardware and equipment that delivers controlled flow into the crack.
Coordinate with adjacent Sika repair when surface restoration follows injection, and our broader Sika services. For residential foundation work in particular, see also foundation crack repair.
Recent work
How it works
How We Inject Cracks in Portland
Classify each crack
We assess each crack for activity (moving or stable), water presence (wet or dry), and structural role (load-carrying or cosmetic), then pick polyurethane or epoxy based on the actual condition.
Install injection ports
Ports are installed at engineered spacing along the crack, the crack surface is sealed with paste between ports to contain the injection material, and the system is ready for chemistry.
Inject Sika product
The Sika polyurethane or epoxy is injected at controlled pressure through each port in sequence, allowing the material to fill the crack full-depth before moving to the next port.
Cure, remove ports, seal
The material cures (polyurethane fast, epoxy slower) and ports are removed, the surface is sealed with matching paste, and the repair is verified for proper fill before being handed off.
Active vs dormant
Polyurethane Is the Wet-Crack Answer
Active wet cracks where water is currently flowing or seeping cannot be repaired with epoxy; the water displaces the epoxy and prevents proper bond. Polyurethane reacts with the water itself, expanding to fill the crack and bond to the wet surface. We use it for any active leak situation; epoxy gets reserved for structural restoration of dry, dormant cracks.
Coordinate with adjacent Sika waterproofing when the larger waterproofing strategy needs review, and with Sika repair for surface restoration after injection.
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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