how to fix foundation cracks by yourself

How To Fix Foundation Cracks by Yourself

Foundation cracks can be a homeowner’s worst nightmare, leading to serious structural issues if not addressed promptly. While some cracks may require professional intervention, homeowners can fix many with the right tools and knowledge. This guide will walk you through how to fix foundation cracks by yourself and explain why it’s essential to waterproof the foundation after making repairs.

Understanding Foundation Cracks

Before diving into the repair process, it’s essential to understand the types of foundation cracks and their potential causes. They can be broadly classified into three categories:

1. Hairline Cracks: These thin cracks often occur due to concrete shrinkage as it cures. They are usually not a cause for alarm.

2. Settlement Cracks: These occur when foundation parts settle unevenly. They can be vertical, horizontal, or diagonal and may indicate potential structural issues.

3. Structural Cracks: These are more serious and can be caused by soil movement, hydrostatic pressure, or poor construction. They often appear wider than hairline cracks and may require immediate attention.

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Tools and Materials You’ll Need

To fix cracks by yourself, you will need the following tools and materials:

  • Safety goggles and gloves
  • Wire brush
  • Chisel and hammer
  • Shop vacuum
  • Crack injection kit (includes epoxy or polyurethane foam)
  • Putty knife
  • Caulk gun
  • Concrete patching compound
  • Trowel
  • Waterproofing sealant

Step-by-Step Guide on How to Fix Foundation Cracks by Yourself

Step 1: Inspect the Cracks

Start by inspecting the cracks to determine their type and severity. Measure the width and length of each crack. Consult a professional if any cracks are wider than 1/4 inch or show signs of structural damage.

Step 2: Prepare the Crack

Wear safety goggles and gloves before starting the preparation. Use a wire brush to clean the crack, removing any loose debris or dirt. Use a chisel and hammer to widen the crack slightly to ensure the filler material adheres properly to larger cracks. Clean the crack thoroughly with a shop vacuum to remove all dust and particles.

Step 3: Apply the Crack Injection Kit

Crack injection kits, which use either epoxy or polyurethane foam, are effective for repairing non-structural cracks. Epoxy is best for dry cracks, while polyurethane foam works well for cracks exposed to moisture.

1. Install Injection Ports: Following the instructions in your crack injection kit, install the injection ports along the crack at regular intervals (usually every 6 to 12 inches). Secure them with epoxy paste.

2. Seal the Crack Surface: Using a putty knife, apply the epoxy paste over the crack surface, ensuring the crack is completely sealed except for the injection ports. Allow the epoxy to cure as per the manufacturer’s instructions.

3. Inject the Filler Material: Use a caulk gun to inject the epoxy or polyurethane foam into the ports, starting from the lowest port and working your way up. Fill each port until the material flows out of the next port. Plug the ports as you move up to prevent backflow.

Step 4: Patch Larger Cracks

For larger or structural cracks, a concrete patching compound is more suitable.

1. Mix the Compound: Follow the manufacturer’s instructions to mix the concrete patching compound.

2. Apply the Patch: Use a trowel to apply the patching compound to the crack, pressing it firmly to ensure it fills the entire crack. Smooth the surface and feather the edges to blend with the surrounding area.

3. Allow to Cure: Let the patch cure per the manufacturer’s instructions. This usually takes several hours to a few days.

Step 5: Remove Injection Ports

Once the filler material has fully cured, remove the injection ports by breaking them off at the surface. Smooth the area with a putty knife if necessary.

Waterproofing the Foundation

After fixing the foundation cracks, it’s crucial to waterproof the foundation to prevent future water damage. Waterproofing helps protect the foundation from moisture infiltration, which can cause new cracks and exacerbate existing ones.

Step 1: Clean the Foundation Surface

Ensure the foundation surface is clean and free of debris. Use a wire brush or pressure washer to remove dirt or loose material.

Step 2: Apply Waterproofing Sealant

1. Choose a Sealant: Select a waterproofing sealant suitable for your foundation material. Standard options include liquid rubber, masonry sealant, or bituminous coating.

2. Apply the Sealant: Use a brush or roller to apply the sealant evenly over the foundation surface. Make sure to cover all repaired areas thoroughly. Apply additional coats as the manufacturer recommends, allowing each coat to dry completely before applying the next.

Step 3: Inspect and Maintain

Regularly inspect the foundation for any new cracks or signs of moisture infiltration. Maintaining proper drainage around your home, such as cleaning gutters and ensuring the ground slopes away from the foundation, can help prevent future issues.

You may also want to call a professional waterproofer to protect your foundation. We offer a comprehensive 25-year warranty on exterior foundation waterproofing.

When to Call a Professional

While homeowners can repair many cracks, some situations require professional expertise:

  • Cracks wider than 1/4 inch or those that appear to be growing
  • Horizontal cracks, which may indicate severe structural issues
  • Cracks accompanied by bowing or shifting of foundation walls
  • Persistent water leakage despite repairs

In such cases, it’s best to consult a structural engineer or foundation repair specialist to assess the damage and recommend appropriate solutions.


Fixing foundation cracks yourself can be a cost-effective way to maintain the integrity of your home. By following the steps outlined in this guide, you can address minor cracks and prevent them from developing into more severe problems. Remember, after repairing the cracks, it’s essential to waterproof your foundation to protect it from future water damage. Regular inspection and maintenance will help ensure your foundation remains solid and secure for years.

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