How to Seal a Hairline Foundation Crack with an Epoxy Injection Kit
Time required: 1-2 hours (plus 24-48 hr cure) · Difficulty 2/5
Epoxy injection kits are only rated for non-structural, dormant hairline-to-1/4 inch cracks in poured concrete. If the crack is wider, actively growing, stair-stepped in a block wall, or accompanied by bowing/leaning, stop and get a structural engineer or foundation contractor to inspect it — DIY sealant will not fix a structural problem and some insurers may not cover resulting damage if a known structural issue was left unaddressed.
Est. DIY Parts: $80 - $110 · Pro Service: $400 - $800 · Est. Savings: $300 - $700
* Estimates based on regional/national contractor rate benchmarks. Actual part prices vary by brand and retailer.
Parts & Tools You'll Need
- 10 ft. DIY Foundation Crack Epoxy Injection Kit
- Wire Brush Wheel (for surface prep)
- Standard Caulk Gun
- Safety Glasses & Gloves
Step-by-Step Manual
- Clean the crack and surrounding surface Use a wire brush to remove loose concrete, efflorescence, paint, or coating for about 1-2 inches on either side of the crack, then wipe away dust.
- Install injection ports along the crack Position the plastic injection ports directly over the crack every 8-12 inches, per your kit's instructions.
- Seal the crack surface with paste Spread the surface sealant paste over the entire crack length and around each port's base, leaving only the port opening exposed. Let it set as directed (often 1-4 hours).
- Mix and inject the epoxy Mix the two-part epoxy per the kit instructions and load it into a caulk gun. Starting from the lowest port, inject until epoxy flows out of the next port up, then cap and move to the next.
- Let it cure fully before removing ports Allow the epoxy to cure for 24-48 hours (check your kit's label), then snap off the exposed ports and grind the surface paste flush if desired.