Cracks in Load-Bearing Walls of Prefabricated Panel Houses

The danger level of cracks in the load-bearing walls of prefabricated panel houses should be professionally assessed according to the 'Standards for Dangerous House Appraisal' (JGJ 125-2016). Typically, cracks are classified as Class C (local danger) or Class D (overall danger) based on their characteristics.

Criteria for Class C (Local Danger)

If the cracks in the load-bearing wall meet the following characteristics, they can be preliminarily classified as Class C:

1. The cracks do not penetrate the wall, appearing only in localized areas, with a crack width ≤ 5mm.
2. No structural tilting, with no significant deformation of the overall building (tilt rate ≤ 1%).
3. Load-bearing capacity decreased by ≤ 30%, with the structure still able to maintain basic load-bearing functions.
4. Common causes: Non-structural cracks caused by temperature stress (e.g., seasonal thermal expansion and contraction), minor foundation settlement, or construction errors.
   Typical scenarios: Horizontal cracks caused by wall contraction in winter or localized cracking due to decoration drilling. These cracks generally do not affect the overall safety of the building but require regular monitoring for changes.

Criteria for Class D (Overall Danger)

If the cracks meet the following characteristics, they should be immediately classified as Class D, and emergency measures should be taken:

1. The cracks penetrate the wall, causing through-wall damage, with a width > 5mm.
2. Accompanied by significant tilting (tilt rate > 1%) or structural deformation of walls and floors (e.g., floor deflection, beam and column cracking).
3. Loss of load-bearing capacity ≥ 50%, with the structure unable to withstand the designed load, posing a risk of collapse.
4. Common causes: Structural damage caused by earthquakes, severe foundation deformation (e.g., soft soil layer settlement), material aging (e.g., concrete carbonation, steel reinforcement corrosion), or fires.
   Typical scenarios: 'X'-shaped through-wall cracks after an earthquake or overall tilting caused by long-term leakage leading to foundation softening. These cracks require immediate evacuation of personnel and commissioning of a professional organization for reinforcement or demolition and reconstruction.

Key Factors for Comprehensive Assessment

Professional appraisal should be based on a comprehensive evaluation of the following dimensions:

1. Dynamic changes in cracks: If the cracks significantly lengthen or widen within six months or new cracks appear, the risk level may escalate.
2. Accompanying phenomena: Sudden sticking of doors and windows, significant deformation of floors, concrete spalling, or exposed steel reinforcement all indicate severe structural damage.
3. Connection status of components: Check whether the connection nodes between the load-bearing wall and beams, floors, and columns are loose or cracked.
4. Overall deformation of the building: Measure the tilt rate using a total station or detect floor flatness with a laser level.

Recommendation: Upon discovering cracks in the load-bearing wall, immediately contact the local housing and construction department or a qualified house safety appraisal organization for inspection to avoid delays in disposal due to self-assessment.