Cracks in your foundation aren’t just cosmetic they could be telling you something important. While some small cracks are normal in aging homes, others point to serious structural concerns. Understanding which is which can help you take the right action before the problem grows.

Types of Foundation Cracks

Not all cracks are equal. Here are the most common types and what they might mean:

• Vertical cracks: Usually the result of normal settling and less serious
• Horizontal cracks: May indicate pressure from expanding soil or water
• Stair-step cracks in brick: Often a sign of foundation movement
• Diagonal cracks: Could suggest differential settling

What Causes Foundation Cracks?

Cracks can be triggered by various factors, including:

• Poor soil conditions or moisture fluctuations
• Improper drainage or clogged gutters
• Tree root invasion
• Poor construction practices

When Should You Worry?

You should contact a professional if:

• Cracks are wider than 1/4 inch
• You notice bowing walls or uneven floors
• Water is seeping through the cracks
• The crack continues to widen over time

The Role of Polyjacking and Piering

Foundation crack repair isn’t just about sealing the surface. If your foundation is shifting, lifting or stabilizing the slab might be necessary. Polyjacking is excellent for lifting settled slabs, while piering is used to reinforce deeper foundation movement.

Steps in a Crack Repair Appointment

1. Inspection: Technicians examine the crack and surrounding area
2. Assessment: Determining if it’s a surface issue or structural
3. Repair Method: Sealing, foam injection, or reinforcement as needed
4. Prevention: Addressing moisture, grading, or drainage issues

Types of Foundation Cracks and What They Mean

Different cracks signal different issues. Here’s how to identify them:

Hairline Cracks

• Appearance: Thin, less than 1/16 inch wide.
• Cause: Normal shrinkage as concrete cures.
• Concern Level: Low—usually cosmetic. Monitor for growth.

Vertical Cracks

• Appearance: Straight up-and-down lines, wider at top or bottom.
• Cause: Settlement or soil movement.
• Concern Level: Moderate. If wider than 1/4 inch or active movement occurs, seek professional advice.

Diagonal Cracks

• Appearance: Slanted lines, typically 30–45 degrees.
• Cause: Uneven settlement—one part of foundation sinking more.
• Concern Level: High. May indicate serious structural issues. Inspect immediately.

Stair-Step Cracks

• Appearance: Crack follows mortar joints in concrete blocks, resembling stairs.
• Cause: Lateral soil pressure or uneven settlement.
• Concern Level: High. Often requires wall repair or reinforcement.

Horizontal Cracks

• Appearance: Straight horizontal lines across walls.
• Cause: Excessive soil pressure or hydrostatic pressure from water.
• Concern Level: Very High. Signals significant structural stress—act quickly.

Assessing Crack Severity

When you spot a crack, measure and document it:

1. Measure Width: Use a ruler or crack gauge.
2. Monitor Growth: Mark ends with pencil and date. Check monthly.
3. Notice Location: In basement walls, floors, or exterior foundation.
4. Check for Secondary Signs: Warped windows, sticking doors, sloping floors.

If cracks widen over time or you see additional issues (water leaks, mold), call a foundation specialist.

When to Call a Professional

Some repairs are DIY-friendly, but serious cracks need expert help. Consider professional assessment if you see:

• Horizontal or stair-step cracks over 1/8 inch.
• Rapidly widening cracks.
• Bowed or bulging walls.
• Doors and windows that jam.
• Pooled water inside or outside foundation.

A structural engineer or licensed foundation contractor can perform a detailed evaluation and recommend solutions.

Repair Options for Different Cracks

Filling Hairline and Small Vertical Cracks

• Materials: Epoxy or polyurethane injection kits.
• Process: Clean the crack, inject sealant under pressure, and smooth the surface.

Repairing Diagonal and Stair-Step Cracks

• Underpinning: Stabilize sinking sections with helical piers or push piers driven into stable soil.
• Wall Anchors: Install anchors outside the foundation to pull bowed walls back.

Fixing Horizontal Cracks

• Pressure Relief: Install weeping tiles or French drains to divert water away.
• Reinforcement: Add steel beams or carbon-fiber straps to support walls.

Waterproofing

• Exterior Sealants: Apply elastomeric coatings to exterior walls.
• Interior Sealants: Use masonry sealers on basement walls and floors.
• Drainage Systems: Install interior drains connected to sump pumps.

Preventing Future Foundation Cracks

Good prevention keeps repairs at bay:

Maintain Proper Drainage

• Clean gutters and downspouts to direct water away.
• Grade the yard so it slopes away from the foundation.
• Install French drains if water pools near the house.

Control Soil Moisture

• Water the foundation perimeter during dry spells to prevent soil shrinkage.
• Avoid overwatering plants close to the house.
• Mulch garden beds to retain consistent moisture.

Manage Trees and Shrubs

• Keep large trees at least 15–20 feet away from the foundation.
• Remove or prune invasive root systems.
• Plant smaller shrubs near the house.

Regular Inspections

• Check for new cracks semi-annually.
• Look for signs of movement after heavy rains or droughts.
• Address minor cracks before they grow.

Cost Considerations

Foundation repairs vary widely in cost:

• Epoxy Injection: $250–$800 per crack.
• Underpinning (Piers): $1,000–$3,000 per pier; total $5,000–$20,000.
• Wall Anchors: $1,000–$1,500 per anchor; total $5,000–$30,000.
• Waterproofing & Drainage: $3,000–$10,000 for interior drains and sump pump installations.

Get multiple quotes, ask about warranties, and consider long-term value over cheapest price.

Insurance and Warranties

• Homeowner’s Insurance: Typically covers sudden damage (e.g., burst pipe) but not gradual cracking.
• Foundation Warranties: Many contractors offer 5–25 year warranties on repairs and stabilization systems.
• Transferable Warranties: If you sell your home, some warranties transfer to the new owner, adding resale value.

Always read the fine print and understand coverage limits.

Hiring the Right Contractor

When choosing a foundation specialist:

1. Check Licensing and Insurance: Ensure they are bonded and insured.
2. Read Reviews: Look for positive feedback on HomeAdvisor, Angie’s List, or Google.
3. Ask for References: A reputable contractor should provide recent customer contacts.
4. Get a Written Proposal: It should detail scope, methods, timeline, and cost breakdown.
5. Verify Warranties: Understand what is covered and for how long.

Trustworthy contractors prioritize communication and transparent pricing.

Conclusion

A foundation crack is telling you something important about your home’s stability. While hairline cracks may be harmless, horizontal or stair-step cracks often signal serious structural or water issues. By understanding what cracks in foundations mean, you can decide when to DIY and when to call a professional. Regular inspections, proper drainage, and soil moisture control help prevent future damage. If you do need repairs, choose the right contractor and consider long-term warranties. Addressing foundation cracks early protects your home’s value and ensures a safe, dry living space for years to come.

Ignoring cracks can lead to bigger problems. But the right repair at the right time can restore safety and value to your home. If you’re concerned about cracks in your basement or foundation walls, STL Polyjack offers reliable foundation crack services in St. Louis to get the job done right the first time.