Common Causes of Stucco Cracks
Shrinkage Cracks
Small, hairline cracks often appear as stucco cures and dries. These are generally cosmetic and result from normal curing shrinkage.
Thermal Expansion and Contraction
Stucco expands and contracts with temperature changes. Without proper control joints, this movement can result in cracking.
Improper Application
If stucco is applied too thin, without sufficient curing, or in poor weather conditions, cracking is more likely.
Foundation Movement
Settlement or differential movement in the foundation can cause larger, more pronounced cracks in stucco walls.
Moisture Intrusion or Freeze-Thaw Cycles
In cold climates, water that penetrates stucco and freezes can expand, creating cracks or widening existing ones.
Types of Stucco Cracks
Hairline Cracks (<1/16 inch): Typically cosmetic, caused by curing or minor movement.
Spiderweb or Map Cracks: Usually indicate improper application or curing.
Vertical/Diagonal Cracks: May signal structural movement, foundation settlement, or seismic activity.
Wide or Stair-Step Cracks: Often associated with more serious structural shifts or moisture damage beneath the stucco.
Risks of Unrepaired Cracks
Water Intrusion: Even small cracks can allow moisture to penetrate behind stucco, leading to rot, mold, or damage to framing.
Worsening Over Time: Cracks can expand with seasonal changes or building movement if left unaddressed.
Loss of Weatherproofing: Stucco’s primary function as a protective shell is compromised.
Aesthetic Concerns: Cracks detract from curb appeal and may affect property value.
Recommended Repairs
Hairline Cracks:
Seal with a high-quality elastomeric caulk or stucco patch material.
Repaint with elastomeric paint for additional protection.
Moderate Cracks:
Use a flexible patching compound designed for stucco.
Feather patch into existing finish for visual uniformity.
Structural or Wide Cracks:
Investigate underlying causes such as settlement, water intrusion, or framing issues.
May require removal and reapplication of sections of stucco, reinforcement, or foundation repair.
Conclusion
Stucco cracks should be evaluated by type and severity. Small cracks are often cosmetic and can be sealed, but larger or recurring cracks may indicate structural or moisture problems requiring further evaluation by a qualified contractor or engineer. Prompt attention ensures the stucco system continues to protect the home effectively.