How to Fix Cracked Concrete

Overview

Cracked concrete is common in driveways, patios, and walkways. While some cracks are cosmetic, others can worsen and cause problems if not addressed. This guide covers how to assess cracks and repair them effectively, from small hairline cracks to larger structural issues.

Why This Matters

Unrepaired cracks allow water penetration, which can worsen damage through freeze-thaw cycles. Cracks also create tripping hazards and reduce the appearance of your property. Early repair prevents small problems from becoming expensive replacements. Most concrete crack repairs are straightforward DIY projects.

Types of Cracks

Hairline Cracks

Size: Less than 1/8 inch wide Severity: Usually cosmetic Repair: Simple sealant application Difficulty: Easy

Small Cracks

Size: 1/8 to 1/4 inch wide Severity: May worsen if not addressed Repair: Crack filler or sealant Difficulty: Easy to moderate

Medium Cracks

Size: 1/4 to 1/2 inch wide Severity: Needs proper repair Repair: Concrete patching compound Difficulty: Moderate

Large Cracks

Size: Over 1/2 inch wide Severity: May indicate structural issues Repair: Professional assessment recommended Difficulty: Advanced

Step 1: Assess the Crack

Determine Severity

Check for:

• Width - Measure at widest point
• Depth - How deep does it go?
• Movement - Is it getting wider?
• Location - Foundation vs. surface
• Cause - Tree roots, settling, etc.

When to Call a Professional

Seek professional help if:

• Crack is very wide (over 1/2 inch)
• Foundation cracks - Structural concern
• Crack is expanding - Indicates ongoing problem
• Multiple large cracks - May indicate serious issue
• Vertical displacement - One side higher than other

Step 2: Prepare the Crack

Clean Thoroughly

Preparation steps:

1. Remove loose material - Chisel out loose concrete
2. Clean debris - Wire brush to remove dust and dirt
3. Remove vegetation - Pull out any weeds or roots
4. Blow out - Use compressed air or shop vac
5. Ensure dry - No moisture in crack

Shape the Crack

For better adhesion:

• Undercut edges - Slightly wider at bottom (keyway)
• Remove loose edges - Clean, solid edges
• Create clean surface - For filler to bond

Step 3: Choose Repair Material

For Small Cracks (Under 1/4 inch)

Options:

• Concrete caulk - Flexible, easy application
• Liquid crack filler - Self-leveling, penetrates deep
• Epoxy injection - Strong, permanent (for active cracks)

For Medium Cracks (1/4 to 1/2 inch)

Options:

• Concrete patching compound - Fills and bonds
• Vinyl concrete patcher - Flexible, durable
• Hydraulic cement - Expands as it cures

Step 4: Apply Filler

For Small Cracks

Application:

1. Apply sealant - Follow product instructions
2. Work into crack - Ensure complete filling
3. Smooth surface - Remove excess
4. Allow to cure - Follow product time requirements

For Medium Cracks

Application:

1. Mix compound - If powder, follow instructions
2. Apply bonding agent - If recommended
3. Fill crack - Press compound into crack
4. Smooth surface - Level with surrounding concrete
5. Cure properly - Keep moist if required

Step 5: Finish and Cure

Surface Finishing

After filling:

1. Smooth surface - Match surrounding concrete
2. Remove excess - Clean edges
3. Texture match - If needed, match existing texture
4. Protect during cure - Cover if needed

Curing

Important:

• Follow product instructions - Curing times vary
• Keep dry - During initial cure
• Avoid traffic - Until fully cured
• Protect from weather - If needed

Prevention

Address Underlying Causes

If possible:

• Remove tree roots - If causing cracks
• Improve drainage - Prevent water issues
• Control joints - Add if missing
• Reduce loads - If overloaded

Maintenance

Ongoing care:

• Seal concrete - Every 2-3 years
• Inspect regularly - Catch cracks early
• Address promptly - Small repairs are easier
• Maintain drainage - Prevent water issues

Common Mistakes to Avoid

Inadequate Preparation

Don't: Fill dirty or wet cracks Do: Clean thoroughly and ensure dry

Wrong Material

Don't: Use inappropriate filler for crack size Do: Match material to crack type and size

Rushing

Don't: Use before fully cured Do: Allow proper cure time

When to Call a Professional

Call a professional if:

• Crack is very large (over 1/2 inch)
• Foundation cracks - Structural assessment needed
• Multiple serious cracks - May indicate major problem
• Crack is expanding - Ongoing movement
• You're uncomfortable with the repair

Cost Considerations

DIY repair:

• Materials: $20-$100 (depending on crack size/number)
• Tools: $20-$50 (if needed)
• Total: $40-$150

Professional service:

• Per crack: $100-$300
• Multiple cracks: $300-$1,000+
• Foundation repair: $500-$5,000+

Conclusion

Fixing cracked concrete is a manageable DIY project for most homeowners. The key is proper assessment, thorough preparation, choosing the right repair material, and allowing proper cure time. Small cracks are easy to fix and prevent from becoming larger problems. For serious cracks or foundation issues, professional assessment is recommended.