Two distinct injection chemistries solve two distinct crack problems. Polyurethane expands on water contact, stopping active leaks in real time. Epoxy bonds dormant cracks to full structural strength. We diagnose which condition you have, select the right Sika product, and inject to complete depth. No guesswork, no failed repairs.
Not all cracks are the same, and not all injection chemistries work on all cracks. A wet, actively leaking crack needs polyurethane because the water itself triggers the chemical reaction, causing the material to expand and seal. Epoxy cannot cure in the presence of water; it will fail on an active leak. Conversely, epoxy is the structural choice for dry, dormant cracks because it bonds the two sides of the crack into a single monolithic unit. Polyurethane in a dry crack wastes material and leaves the crack mechanically weak.
The first step is always diagnosis. We assess whether the crack is moving or stable, wet or dry, and whether it carries structural load. Once we know the actual condition, the chemistry choice becomes obvious. Sika manufactures both polyurethane and epoxy in injection-grade formulations with the ports and equipment needed for controlled, full-depth delivery.
We examine the crack for activity (stable or moving), moisture (wet or dry), and structural role (load-bearing or non-structural). This assessment determines whether polyurethane or epoxy is the right choice.
Install injection ports
Ports are positioned at intervals calculated from the crack width and depth. The crack surface is sealed with paste between ports to contain the injection material and prevent leakage.
Inject the Sika product
Polyurethane or epoxy is injected through each port in sequence at controlled pressure, allowing the material to fill the entire crack depth before advancing to the next port.
Cure, remove ports, finish
The material cures according to its chemistry (polyurethane fast, epoxy slower). Ports are removed, the surface is sealed with matching paste, and the repair is verified for complete fill.
For active leaks
Polyurethane Injection Stops Water in the Crack
When water is actively flowing or seeping through a crack, epoxy will not work. The water prevents epoxy from curing and bonding. Polyurethane is engineered for this exact scenario. The water in the crack triggers the polyurethane to expand, filling the crack and bonding to the wet concrete surface. The leak stops during injection, not weeks later. This is the chemistry for basements, foundation walls, and any slab where water is present at the time of repair.
Polyurethane injection is often paired with Sika waterproofing on the exterior or interior surface to create a complete water-management strategy. See also basement concrete and basement crack repair for the full scope of foundation water control.
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, Detroit
★★★★★
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, Warren
★★★★★
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, Ann Arbor
★★★★★
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, Sterling Heights
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Describe the crack (active or dormant, wet or dry, structural or cosmetic), and we will recommend the matched Sika product and provide a written quote.
