The Simpson Crack-Pac Flex-H2O Polyurethane Crack Sealer Injection Kit from Simpson Strong-Tie is a complete, ready-to-use system engineered to stop water intrusion and permanently seal leaking cracks, voids, and fractures in concrete and solid masonry. Formulated specifically for applications where water is actively seeping or mildly leaking, the polyurethane resin reacts with moisture to expand into a flexible foam seal - closing the crack from the inside out. The kit bundles two 9 oz. cartridge/nozzle sets with all necessary injection hardware and paste-over materials, so professionals and serious DIYers have everything required to complete a proper crack injection repair in a single package.

Key Features

• Seals seeping or mildly leaking cracks in concrete and solid masonry - targets the most common and damaging water-intrusion scenario, stopping active leaks rather than just surface-coating them.
• Polyurethane is packaged in the cartridge; accelerator is packaged in the nozzle - keeps components separated until use, eliminating premixing and reducing waste on the job.
• Dispensed with a standard caulking tool - no specialized injection pump required, making this system accessible for a wider range of users and jobsite conditions.
• Expands on contact with moisture to fill voids and seal the affected area - foam expansion conforms to irregular crack geometry, creating a thorough seal even in hard-to-reach voids.
• Fast reacting - reaction begins within 1 minute after exposure to moisture; expansion may be completed within 3 minutes - minimizes downtime and allows crews to move quickly through multiple injection points.
• 20:1 expansion ratio (unrestricted rise) - a small volume of material fills a large crack volume, reducing how much product is needed per repair and lowering overall material cost.
• Can also be used on dry cracks if water is introduced to the affected area - extends the product's usefulness beyond wet conditions, making it a versatile option for both leaking and non-leaking repairs.
• Accelerator can be reduced or omitted to slow reaction time - gives applicators control over working time, which is especially useful in large or complex crack profiles that require more precise placement.

Why This Product

• A true all-in-one injection kit - the included cartridge/nozzle sets, E-Z-Click injection ports, injection fittings with tubing, ETR paste-over epoxy, applicators, and gloves mean there is no need to source individual components separately, reducing prep time and the risk of missing a critical item on the job.
• Built for active water conditions - unlike surface-applied patching materials, this polyurethane injection resin is specifically designed to perform where water is present, using moisture itself to trigger the expanding foam seal rather than fighting against it.
• Flexible seal accommodates real-world movement - the cured polyurethane foam remains flexible after expansion, making it appropriate for cracks subject to minor movement and reducing the chance of re-cracking at the repair site.
• High expansion ratio means more coverage with less material - the 20:1 unrestricted expansion ratio allows the two included cartridges to cover more linear crack footage than a comparable volume of non-expanding filler, delivering greater value per repair.

Specifications

• Manufacturer: Simpson Strong-Tie
• MPN: CPFH09KT
• Product Type: Polyurethane Crack Sealer Injection Kit
• Total Capacity: 18 oz.
• Crack Width Range: 1/32 in. to 1/4 in.
• Compatible Substrates: Concrete, Solid Masonry
• Expansion Ratio: 20:1 (unrestricted rise)
• Reaction Time: Begins within 1 minute of moisture exposure; expansion may complete within 3 minutes
• Country of Origin: United States

Approved Applications

• Non-structural crack repair
• Solid brick masonry crack sealing
• Grouted concrete block crack sealing
• Concrete crack and void repair
• Water and wastewater facility crack repair
• Water-intrusion prevention in concrete and masonry structures

What's Included

Each kit contains 2 Crack-Pac Flex-H2O 9 oz. cartridge/nozzle sets, 12 E-Z-Click injection ports, 2 E-Z-Click injection fittings with 12" tubing, 1 pint of ETR paste-over epoxy (8 oz. of resin + 8 oz. of hardener), 4 disposable wood paste-over applicators, 1 pair latex gloves.

Frequently Asked Questions

What types of cracks can the Crack-Pac FLEX-H2O seal?

The Crack-Pac FLEX-H2O polyurethane injection resin is designed to seal leaking cracks, voids, or fractures from 1/32 in. to 1/4 in. wide in concrete or solid masonry. It is specifically formulated to perform in applications where water is seeping or mildly leaking from the crack, and it also provides a flexible seal in non-leaking cracks.

Can this product be used on dry cracks where there is no active water seepage?

Yes. The Crack-Pac FLEX-H2O can also be used on dry cracks if water is introduced to the affected area. The polyurethane resin requires moisture to activate its expansion - so wetting the crack surface prior to injection will initiate the foaming and sealing reaction even in the absence of active water intrusion.

How quickly does the Crack-Pac FLEX-H2O react after injection?

The product is fast reacting - the reaction begins within 1 minute after exposure to moisture, and expansion may be completed within 3 minutes, depending on the amount of moisture present and the ambient temperature. The 20:1 expansion ratio (unrestricted rise) ensures thorough void fill with less material.

What special equipment is needed to apply the Crack-Pac FLEX-H2O?

No specialized equipment is required. The Crack-Pac FLEX-H2O can be dispensed with a standard caulking tool, making it accessible for a wide range of users. The CPFH09KT kit also includes E-Z-Click injection ports and fittings with tubing, paste-over epoxy, applicators, and gloves - everything needed to pressure inject cracks without sourcing additional supplies.

Downloads and Resources

• Epoxy Crack Injection Guide
• Safety Data Sheets for Crack-Pac Flex-H2O