Standard for Prefabricated Slab Brick-Concrete Houses

The standard for prefabricated slab brick-concrete houses is primarily based on the 'Standard for Dangerous House Appraisal' (JGJ 125-2016), which evaluates houses from three aspects: foundation, load-bearing structure, and overall stability. It also classifies appraisal grades and covers the specifications and structural characteristics of early prefabricated slabs.

I. Foundation Appraisal Standards

1. Major Safety Hazards:
   • Uneven settlement of the foundation leading to wall cracking, tilting, and settlement rates or cumulative settlement exceeding allowable norms;
   • Foundation displacement exceeding 10mm, affecting the safety of the superstructure;
   • Cracks on the ground parallel to the slope wider than 10mm, or house tilting reaching H/250 (H being the house height).
2. General Safety Hazards:
   • Slight uneven settlement or cracks not reaching the level of major safety hazards.

II. Load-Bearing Structure Appraisal Standards (Brick-Concrete Structure)

1. Major Safety Hazards:
   • Multiple vertical or diagonal cracks in walls with widths or lengths exceeding normative limits;
   • Significant deflection in cantilevered components such as balconies and canopies;
   • Severe cracking, deformation, or loose connections in prefabricated slabs.
2. General Safety Hazards:
   • Vertical wall cracks not meeting major hazard criteria;
   • Vertical through-cracks at the junctions of longitudinal and transverse walls;
   • Minor cracks or deformation in prefabricated slabs.

III. Overall House Stability Appraisal

Based on the appraisal results of the foundation and load-bearing structure, if the house exhibits severe tilting, deformation, or significant damage to the load-bearing structure, it is classified as a whole-building dangerous house.

IV. Appraisal Grade Classification

1. Grade A: The structural load-bearing capacity meets normal usage requirements with no dangerous points.
2. Grade B: The structural load-bearing capacity basically meets requirements, with individual components in a dangerous state but not affecting the overall safety.
3. Grade C: The load-bearing capacity of some structural components is insufficient, with local hazards in the house.
4. Grade D: The load-bearing capacity of the structural components is severely insufficient, with overall hazards in the house.

V. Specifications and Structural Characteristics of Early Prefabricated Slabs

1. Specifications: The maximum span is 4.2 meters, with widths mostly being 500mm or 600mm, and thicknesses primarily 120mm or 150mm.
2. Limitations: Poor overall integrity and weak seismic performance. After 2008, the country gradually phased out prefabricated slabs and promoted cast-in-place floor slabs to enhance structural safety.