Settlement Standard for Prefabricated Slab Houses

The settlement standard for prefabricated slab houses requires a comprehensive assessment. Generally, the maximum allowable settlement for houses is typically controlled within 20 millimeters, and exceeding this range may be considered unqualified.

I. Core Standards for Settlement Amount
For ordinary prefabricated slab houses, controlling the settlement amount is a fundamental indicator for assessing structural safety. According to engineering practice, the maximum allowable settlement amount generally does not exceed 20 millimeters. This value is set based on the normal usage requirements and structural durability requirements of the house. If the settlement amount exceeds this threshold, it may cause issues such as wall cracking and window/door deformation, necessitating further testing of structural stability.
For rural self-built houses, the settlement amount standard needs to be dynamically adjusted based on specific conditions. Geological conditions (such as soft soil, collapsible loess, etc.), building structural types (brick-concrete, frame, etc.), and design requirements (foundation form, load distribution, etc.) all affect the reasonable settlement range. For example, for houses built on soft soil foundations, the allowable settlement amount may need to be appropriately relaxed, but safety must be verified through professional calculations.

II. Associated Risks of Settlement Differential and Tilt
Settlement assessment should not focus solely on absolute settlement amount; settlement differential (the difference in settlement amounts between adjacent parts) and overall tilt are equally critical. If the sinking of prefabricated slabs causes a significant settlement differential in adjacent areas (such as exceeding 0.002L, where L is the adjacent column spacing), it may trigger redistribution of internal structural forces, causing cracking of load-bearing components (such as beams and columns) or damage to connection nodes.
In terms of overall tilt, when the tilt rate of the house exceeds 0.004 (i.e., a tilt of 4 millimeters per meter of height), it may affect living comfort and structural safety. Tilt may be caused by uneven settlement and requires comprehensive judgment through measuring the house's verticality or foundation deformation.

III. Basis for Determining Safety Hazards
According to the technical guidelines for structural safety inspection of self-built houses, if a house exhibits the following conditions, it is considered to have serious safety hazards:

1. Unstable foundation: Such as continuous settlement, local collapse, or sliding of the foundation;
2. Significant uneven settlement: Causing cracking or deformation of load-bearing components (such as walls and floor slabs);
3. Accumulated structural damage: Such as crack widths exceeding limits (e.g., cracks in load-bearing walls > 0.5 millimeters), or component deformation affecting usability.
   Such houses require immediate commissioning of a professional institution for structural safety assessment and the implementation of reinforcement or reconstruction measures.