Seal foundation cracks with hydraulic cement or polyurethane for $10-$15

Hairline to 1/4-inch foundation cracks from frost heaving are normal in northern climates. Sealing them in April — after the ground thaws and cracks are fully visible — prevents water infiltration that will widen them through the next freeze-thaw cycle.

Steps

1. Clean the crack: Wire brush loose debris and vacuum dust. For wet cracks, use a shop vac to remove standing water.
2. Choose your filler:
3. Sikaflex Self-Leveling Sealant (~$8-$12): Best for horizontal cracks (floors, walkways). Flows into cracks up to 1.5 inches wide. Rated #1 by Bob Vila testing.
4. DAP Liquid Cement Crack Filler (~$8-$10): 4.4 stars from nearly 3,000 reviews. Sets in 45 minutes. Good for vertical foundation wall cracks.
5. Hydraulic cement (~$10-$15 for 10 lbs): For actively leaking cracks. Sets even underwater. Quikrete and Drylok brands are widely available.
6. Apply: Follow product directions. Most fillers cure in 1-24 hours depending on temperature.

When to Call a Pro

• Cracks wider than 1/4 inch
• Horizontal cracks in block walls (indicates serious lateral pressure)
• Stair-step cracks in masonry
• Any crack that is actively growing season to season

Professional epoxy injection for structural cracks: $500-$2,000.

Tips

• Photograph cracks with a ruler for scale each spring to track whether they are growing
• A $10 tube of sealant on a hairline crack now prevents a $5,000-$10,000 structural repair in 2-3 years
• Interior cracks are cosmetic if the exterior is sealed; always prioritize exterior-facing cracks