How to Waterproof a Concrete Basement Crack

Waterproofing concrete cracks will prevent further damage.

Cracks in a concrete basement can be caused by a number of things, including structural strain, water leaks and the freeze-thaw cycle made worse by unheated basement conditions. If water is the cause of the cracking, leaving the crack unrepaired may lead to worsening of the damage. Filling in the crack with concrete compound will fix the crack, but waterproofing it first will prevent the damage from coming back.

Things You'll Need

• Wire brush
• Shop vacuum
• Concrete sealer
• Paintbrush
• Two-component concrete resin
• Silica sand
• 150-grit sandpaper

Instructions

1. Brush the crack out with a wire brush to remove any loose pieces or debris. Vacuum the crack with a shop vacuum.

2. Paint the crack with a concrete sealer. Sealers penetrate the porous concrete and prevent further water damage. Let the sealer dry according to the package directions.

3. Insert the two-component concrete resin into the application gun. Squeeze a thin bead into the crack to prime it.

4. Use your hands to push silica sand into the crack and into the resin primer. Cover the sand with one additional bead of the primer. If the crack is too thin for sand, just apply two beads of the resin.

5. Let the resin dry for 10 minutes. Sand the dried resin until it is level with the rest of the concrete.

Tips & Warnings

• This repair only works on concrete basements, not concrete block basements

• Also only vertical walls can be repaired. Horizontal floor cracks should not be repaired in this fashion.

References

• Radon Seal: How to Repair Cracks in Concrete Floors
• You Tube: Concrete Crack Repair for Floors