Prefabricated House Finished Sunken Type

The prefabricated house finished sunken type generally refers to a type of prefabricated house that utilizes underground space for functional design. Its core feature is achieving spatial stratification through a sunken structure, but strict control over safety and applicability is required.

1. Typical Application Scenarios of Sunken Design

Sunken design is often used in prefabricated houses to address terrain elevation differences or expand functional space. For example, in a rural villa case in Jiangsu, the house site had natural elevation differences. The design team created a negative-first-floor space using a sunken structure, setting up functional areas such as a home theater, steam room, and guest rooms, forming a vertical partition with the living space on the first floor. Such designs need to be combined with geological survey data, and professional structural assessments are required to ensure that the foundation bearing capacity meets the requirements, avoiding structural deformation due to uneven foundations.

2. Potential Risks and Countermeasures of Sunken Structures

If the prefabricated house sunken structure experiences sinking or cracking of the prefabricated panels, it may be caused by three factors:

1. Foundation Setting Defects: Such as uncompacted foundations or unlayered compaction of backfill soil, leading to uneven soil settlement;
2. Soil Condition Issues: High groundwater levels or soft soil (such as silty soil), triggering long-term creep;
3. Material Quality Hazards: Insufficient strength of the prefabricated panels or design defects in connection nodes, leading to local stress concentration.
   Such issues may pose risks of structural collapse, shorten the house's service life, and affect aesthetics. The treatment plan should be implemented in steps:

• Immediate Suspension and Assessment: Commission a third-party inspection agency to conduct a comprehensive structural assessment of the house, clarifying the causes of settlement (such as soil quality issues or construction defects);
• Responsibility Definition and Repair: Based on the assessment results, the construction party or material supplier should be responsible for repairs, taking measures such as foundation reinforcement (such as grouting reinforcement), replacement of prefabricated panels, or structural reinforcement;
• Long-term Preventive Measures: Before construction, ensure solid foundation setting (such as using the replacement method to treat soft soil layers), select prefabricated panels that meet national standards, and establish a regular inspection and maintenance system (such as detecting foundation settlement every 5 years).

3. Comparison Between Sunken and Upper Duplex Designs

Both sunken and upper duplex (adding a loft on the top floor) designs are ways to expand space, but their design logic and risk points differ:

• Sunken Design: Focus on solving moisture-proofing (such as setting up waterproof layers and ventilation systems), drainage (such as designing slopes to guide water to collection wells), and structural safety (such as anti-floating design);
• Upper Duplex Design: Focus on loft insulation (such as adding insulation layers), waterproofing (such as using roof waterproofing membranes), and load control (avoiding overweight decoration).
  Both need to comply with standards such as the "Building Structural Load Code," but sunken designs, involving underground space, also need to meet special requirements such as the "Technical Code for Waterproofing of Underground Works."

For further information on specific specifications for the sunken design of prefabricated houses (such as foundation bearing capacity calculations and moisture-proof structural nodes), it is recommended to consult a registered structural engineer or refer to documents such as the "Technical Standard for Prefabricated Concrete Buildings" (GB/T 51231-2016).