Wire brush
Use it for: To remove loose paint, old surface seal, and debris so the new kit can bond to the concrete.
Shop wire brushesBasement foundation repair
How to Replace a Basement Foundation Crack Injection Kit
Replace a basement foundation crack injection kit when you have a non-structural crack that is leaking or has leaked before, and the old ports, paste, or injection material did not hold. The basic job is to clean and dry the crack, install fresh ports and surface seal, inject the new material, and then confirm the wall stays dry.
This repair works best on a typical poured concrete wall crack that is accessible from inside the basement. If the crack is widening, the wall is bowing, blocks are shifting, or water is coming from the floor joint instead of the crack itself, this is probably not the right repair.
Before you start: Match the replacement part to your exact basement foundation before ordering.
Safety first
- Wear gloves and eye protection when scraping old material and handling injection products.
- Work in a well-ventilated area, especially if the kit uses strong-smelling sealants or resins.
- Do not inject a crack in a wall that shows movement, bowing, or major structural damage.
- Keep children and pets away from the repair area until the material has fully cured.
Tools you may need
Putty knife
Use it for: To scrape off failed patch material and spread the surface seal over the crack and ports.
Shop putty knives
Shop vacuum
Use it for: To pull dust out of the crack area before you install the new ports and seal.
Shop wet dry vacuums
Caulk gun
Use it for: Some crack repair kits use cartridges that need a standard caulk gun for injection.
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Safety glasses
Use it for: To protect your eyes from dust, chips, and splashes while cleaning and injecting.
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Nitrile gloves
Use it for: To keep sealant and injection material off your skin during the repair.
Shop nitrile glovesAs an Amazon Associate I earn from qualifying purchases. Repair Riot may earn a commission at no extra cost to you.
Step-by-step fix
Step 1: Make sure a crack injection kit is the right repair
- Look closely at the wall and confirm the water is coming through a visible crack in a poured concrete basement wall, not from a pipe, window, floor joint, or condensation.
- Check whether an older crack injection repair has failed, or whether the crack was never sealed properly in the first place.
- Measure the crack visually. A narrow, stable crack is a better candidate for injection than a crack that is actively widening or offset.
- Mark the top and bottom of the crack so you can follow its full length during the repair.
If it works: You have a visible wall crack that appears stable and accessible, and replacing the crack injection kit matches the problem.
If it doesn’t: If the moisture is coming from the cove joint, a wall penetration, or a plumbing leak, switch to the repair that matches that source instead of injecting the crack.
Stop if:
- The wall is bowing, leaning, or has horizontal cracking with movement.
- Concrete is crumbling, displaced, or badly deteriorated around the crack.
- The crack is in a block wall, stone wall, or another assembly that does not match the kit instructions you bought.
Step 2: Remove the failed repair and prep the wall
- Put on gloves and safety glasses.
- Scrape away loose old surface paste, failed patch material, paint, and any injection ports that are no longer bonded.
- Use a wire brush to clean a strip a few inches wide along the crack.
- Vacuum the area well so dust does not weaken the new bond.
- Dry the wall surface as much as you can. If the wall is damp, let it dry longer before sealing unless your replacement kit is specifically made for active moisture.
If it works: The crack line and surrounding concrete are clean, solid, and dry enough for the new kit to bond.
If it doesn’t: If old material is still firmly stuck but loose at the edges, keep scraping until only solid, well-bonded material remains or the concrete is exposed.
Stop if:
- Water is actively running through the crack and you do not have a kit intended for active leaks.
- The concrete surface keeps flaking apart instead of cleaning up to a solid base.
Step 3: Install the new ports and surface seal
- Lay out the injection ports along the crack according to the spacing shown in your replacement kit instructions.
- Bond each port over the crack so the opening lines up with the crack path.
- Spread the kit's surface seal over the crack between the ports, covering the crack completely and tying each port into the sealed strip.
- Leave the port openings clear so you can inject through them later.
- Let the surface seal cure for the amount of time listed with the kit before you start injecting.
If it works: The crack is sealed on the surface, the ports are attached firmly, and the repair area is ready for injection.
If it doesn’t: If a port shifts or pulls loose before curing, remove it, clean the spot again, and reset it before moving on.
Stop if:
- Ports will not stay attached because the wall is too wet, dirty, or deteriorated to hold the seal.
- The crack branches into multiple moving gaps that the kit cannot cover reliably.
Step 4: Inject the crack from the lowest port upward
- Load the injection material into the applicator or caulk gun if your kit uses one.
- Start at the lowest port on a vertical crack so the material can fill upward.
- Inject slowly until material appears at the next port above, then cap the filled port if your kit uses caps.
- Move to the next port and repeat the process up the crack.
- Work steadily instead of forcing material in fast. Slow pressure usually gives a better fill and reduces blowouts.
If it works: Injection material has moved from port to port, showing the crack is filling through its length.
If it doesn’t: If material does not reach the next port, pause and check for a missed opening, a loose port, or a gap in the surface seal before continuing.
Stop if:
- Injection material blows out through the surface seal in multiple places.
- A port or section of wall will not hold pressure at all, suggesting the crack path or wall condition is not suitable for this repair.
Step 5: Let the repair cure and clean up the surface
- Leave the injected crack alone for the full cure time listed by the kit manufacturer.
- After curing, remove the ports if the kit is designed for port removal.
- Scrape or trim any leftover surface material so the wall is neat and you can inspect it later.
- Bag up used cartridges, gloves, and debris for disposal according to the product label.
If it works: The repair has cured, the wall is cleaned up, and you can clearly inspect the finished crack line.
If it doesn’t: If the material is still soft, give it more cure time before removing ports or stressing the area.
Stop if:
- The repaired area stays tacky or soft far beyond the listed cure time, which can mean the product did not set correctly.
Step 6: Test the repair in real conditions
- Check the repaired crack during the next heavy rain or after the wall has been exposed to the same moisture conditions that caused the leak before.
- Run your hand along the wall and look for damp spots, darkening concrete, or fresh mineral staining.
- Inspect the full crack length, not just the center, because small misses often show up near the top, bottom, or at a branch.
- If the wall stays dry, note the repair date so you can compare it during future wet weather.
If it works: The crack stays dry under real-world conditions, and the replacement repair is holding.
If it doesn’t: If you still see moisture, the crack may not be fully filled, the leak source may be elsewhere, or the wall may need a different waterproofing or structural repair approach.
Stop if:
- Water is still entering at the same crack after the repair has fully cured.
- New cracking, wall movement, or repeated leakage suggests a larger foundation problem.
Replacement Parts
Find a basement foundation crack injection kit on Amazon
Match the replacement part to your exact basement foundation before ordering.
As an Amazon Associate I earn from qualifying purchases. Repair Riot may earn a commission at no extra cost to you.
Verify the repair
- The repaired crack stays dry during the next heavy rain or wet period.
- Ports and surface seal remained bonded during injection and cure.
- No fresh damp spots appear above, below, or beside the repaired crack.
- The wall shows no new movement or widening around the repair.
FAQ
Can I use a crack injection kit on any basement wall crack?
No. These kits are usually best for accessible cracks in poured concrete walls. If the wall is block, stone, badly deteriorated, or structurally moving, a simple injection repair may not be the right fix.
Do I need to remove the old crack repair first?
Yes, if the old ports, paste, or patch are loose or failed. The new kit needs a clean, solid surface to bond well and seal the crack properly.
What if the crack is still wet?
A slightly damp wall may still be repairable with some products, but active running water is a different situation. If water is flowing through the crack, stop and use a product meant for active leaks or get a pro involved.
Should I inject from the top or the bottom?
On a vertical wall crack, start at the lowest port and work upward. That helps the material fill the crack and push air out as it rises.
How do I know the repair worked?
The best check is real weather. Inspect the wall during the next heavy rain or similar wet conditions and look for any fresh dampness, staining, or seepage along the repaired crack.