Find urethane concrete caulk online or at hardware and home improvement stores. Go with urethane caulk if you’re confident the crack doesn’t run deeply through your foundation wall or slab. Caulk can’t penetrate the interior of a deep crack; a concrete injection kit is the way to go if the crack is more than 2 or 3 in (5. 1 or 7. 6 cm) deep.
After scrubbing the surface, sweep or vacuum any remaining dust and debris. Lingering dust will prevent the caulk from bonding with the concrete.
Pause periodically so the compound can seep into the crack as deeply as possible. Wear work gloves when working with urethane caulk. If you get any on your skin, promptly wipe it off with a cloth dipped in paint thinner or mineral spirits.
Wipe your putty knife with mineral spirits as soon as you’ve finished using it.
There are 2 types of injection compounds available. Epoxy is the preferred option for dry cracks in load bearing foundation walls and slabs. Since epoxy can’t bond to wet surfaces, polyurethane is best for cracks that are actively leaking. The application process is basically the same for both compounds. [7] X Research source Feel around the crack to test for dampness. If it feels at all damp, dry it thoroughly with a blow dryer, then check it again after 15 minutes. If it’s still dry, go with epoxy; if it’s wet and won’t dry out, inject it with polyurethane.
If you’re repairing a crack in a foundation wall, lay a drop cloth beneath the work area to protect your floors from drips of repair compound.
Leave enough of each nail’s shaft exposed so about 1⁄2 to 1 in (1. 3 to 2. 5 cm) will protrude past the port’s nozzle. That way, you’ll be able to grasp the extra length to remove the nail. In a pinch, use pins, toothpicks, or thin coffee stirrers instead of nails to align the ports with the crack.
Make sure you don’t cover the injection port’s hole with epoxy. Don’t apply so much epoxy that it’ll spread and clog the hole when you press the port against the wall. When mixed together, the 2 parts form a compound that will cure and harden. Use separate sticks to scoop out the 2 parts to avoid contaminating the containers.
Continue removing the remaining nails before injecting epoxy into the ports.
Check your product’s instructions for the amount of 2-part epoxy needed to cover the crack’s surface area. Scoop out the recommended amounts of each part of epoxy with separate sticks, then mix them together on a piece of scrap wood with a clean putty knife. Wipe your putty knife with a rag and mineral spirits or paint thinner as soon as you’ve finished spreading the epoxy over the crack. The compound will be tough to remove once it has cured.
Use gentle pressure to control the flow as much as possible. Stop squeezing as soon as the compound starts oozing out of the port above the one you’re filling. If too much seeps out, excess epoxy could drip onto the walls.
Stop squeezing the caulk gun’s trigger when the compound oozes out of the port above the one you’re injecting. Repeat the steps until you’ve injected compound into each of the ports.
