Cracks in Prefabricated Panel Houses

Cracks in prefabricated panel houses should be evaluated and addressed based on their type, characteristics, and accompanying phenomena. If structural safety is involved, timely testing and assessment are required.

I. Identification of Crack Types and Characteristics

1. Normal Cracks:

   • Shrinkage Cracks: Caused by concrete shrinkage, these cracks are typically small and evenly distributed, with widths usually ranging from 0.05 to 0.2 millimeters. They are commonly found on the surfaces of walls or floors and have minimal impact on structural safety.
   • Temperature Cracks: Resulting from thermal expansion and contraction due to temperature changes, these cracks are often seen on the top floor or exterior facades. They exhibit regular diagonal or horizontal patterns, are generally thin, and are related to seasonal variations.
   • Settlement Cracks: These cracks occur due to uneven settlement of the foundation. They are relatively wide and may extend from the bottom to the top of the panel, following the direction of settlement. If settlement stabilizes and the cracks stop developing, they usually do not pose a safety risk.

2. Abnormal Cracks:

   • If a crack exceeds 0.3 millimeters in width, continues to expand, or is accompanied by phenomena such as house tilting, concrete spalling, or exposed steel bars, it may indicate structural safety issues. In such cases, immediate委托 (entrustment to) a professional organization for testing and assessment is necessary.

II. Crack Treatment Measures

1. Reinforcement During the Renovation Phase:

   • For smaller cracks, filling the gaps and then applying mesh or carbon fiber cloth can enhance the overall structural integrity and prevent further crack expansion.
   • If cracks are compounded by house aging or human factors (such as renovation or overloading), a comprehensive evaluation of the danger level should be conducted based on the overall deformation of the house and the connection status of components.

2. Structural Safety Treatment:

   • According to the current Standard for Dangerous House Appraisal (JGJ 125-2016), house danger levels are classified into four categories: A (safe), B (basically safe), C (partially dangerous), and D (entirely dangerous). If a house is appraised as Category C or D, reinforcement or demolition and reconstruction should be carried out based on professional recommendations.

III. Policy Recommendations and Routine Maintenance

1. Stay Informed About Policy Updates:

   • Both the 2025 central government document and the 2026 15th Five-Year Plan for Urban Renewal propose governance and renovation measures for prefabricated panel houses. Residents should pay attention to local policies and apply for subsidies for dangerous house renovation or reinforcement.

2. Regular Inspection and Maintenance:

   • It is recommended to inspect the house every six months, focusing on observing whether cracks are expanding, whether walls are tilting, or whether the ground is sinking. Record any changes to provide a basis for subsequent treatment.