Definition of Prefabricated Panel Houses as Grade D Dangerous Buildings

The definition of a prefabricated panel house as a Grade D dangerous building is that the load-bearing capacity of its structural components severely fails to meet requirements, the entire building is in a dangerous condition, and it constitutes a whole-building hazard. Grade D dangerous buildings represent the highest level of danger in the standards for assessing building hazards, indicating that the load-bearing structure can no longer meet safe usage requirements and must be assessed by a professional building safety assessment agency.

I. Severe Inadequacy of Load-Bearing Capacity in Structural Components
The core characteristic of a Grade D dangerous building is a significant decline in the load-bearing capacity of its structural components (such as prefabricated panels, beams, columns, and walls), rendering them unable to support the building's self-weight and normal usage loads. For example, prefabricated panels may fracture or deform due to material aging, steel bar corrosion, or construction defects; walls may develop severe cracks or tilt, leading to a loss of overall structural stability. This inadequacy in load-bearing capacity directly threatens occupant safety and may trigger partial or complete collapse.

II. Overall Building in a Dangerous Condition
A Grade D dangerous building is not limited to local damage but exhibits a failure in the overall structural function of the building. For instance, loose or detached connections between prefabricated panels and walls may cause the floor or roof to sink; uneven settlement of the foundation may lead to building tilting or cracking; widespread corrosion or crumbling of load-bearing components may result in chain-reaction damage. These hazardous conditions indicate that the building can no longer maintain basic usability and is at risk of serious accidents at any time.

III. Criteria for Determining a Whole-Building Hazard
According to the "Standards for Assessment of Building Hazards" (JGJ 125-2016), a Grade D dangerous building must meet the condition of being a "whole-building hazard," meaning the building's structural system is severely damaged and poses a risk of collapse. Assessment involves a comprehensive evaluation of the damage to load-bearing structures, enclosure structures, and equipment and facilities, such as:

• The deflection of the prefabricated panel's mid-span exceeds the specified limit;
• The width of wall cracks exceeds the allowable value and is through-going;
• The building's tilt rate exceeds the threshold for a dangerous state.

IV. Assessment by Professional Agencies Required
The identification of a Grade D dangerous building must be carried out by a qualified building safety assessment agency through on-site inspections, structural analysis, and other means. The assessment report must clearly state the building's hazard level and propose handling recommendations such as reinforcement, demolition, or cessation of use. Individual judgments based solely on appearance cannot accurately define a Grade D dangerous building; scientific testing data is required.