How to Seal a Leak in a Concrete Foundation

If you have leaks in the concrete foundation of your home, it may be due to the absence of waterproofing applications. If this is the case and you only repair the leaking areas, it won't address the overall problem. So after tending to the leaks, take time to waterproof the concrete and prevent future problems.

Things You'll Need

• Wire brush
• Canned air
• Pre-mixed concrete patching compound
• Putty knife
• Grease-fighting soap
• Cleaning brush
• Garden hose
• Concrete sealer
• Paint tray
• Medium-nap paint roller

Instructions

Repair Holes or Cracks

1. Examine the foundation in the area where the concrete is leaking for visible cracks or holes. Remove bits of dislodged concrete from each crack or hole that you find by brushing the interior of the hole with a wire brush. Blow loose debris out of the holes or cracks with canned air.

2. Apply pre-mixed concrete patching compound to the each crack or hole in the foundation with a putty knife, pressing the compound down into the hole to fill it completely. Wipe off the putty knife and drag the edge over the filled crack or hole to remove excess compound. Allow the patches in the foundation to dry three hours and check them.

3. Repeat the filling process on cracks and holes if the patching compound sinks below the level of the foundation once dry. You may need to fill the cracks or holes a few times before the patching compound sits even with the rest of the foundation.

4. Clean the foundation once the holes have been correctly filled. Go over the entire surface with a grease-fighting soap and a cleaning brush to remove dirt and oil from the surface. Rinse the foundation with a garden hose and allow the surface to dry before sealing.

Seal the Concrete Foundation

1. Pour concrete sealer into a paint tray. Dip a medium-nap paint roller into the sealer and roll over the surface of the foundation to apply the sealer.

2. Place the paint roller at the end of the last applied section of sealer and roll backward into the area where the sealer is already applied before moving forward again to prevent streaks in the sealant and ensure proper coverage of the foundation.

3. Apply one coat of sealer to the foundation and allow the sealer to dry completely. Apply at least one more coat of sealer and allow it to dry.

References

• Aubuchon Hardware: How to Repair Concrete
• Ask the Builder: Repair Cracked Concrete Slab: Tim Carter: 2011
• Concrete Sealer Tips: How to Apply Concrete Sealer: 2010