Prefabricated House Third Floor Construction

The construction process of the third floor of a prefabricated house varies depending on the construction case, mainly divided into two modes: integral hoisting and component assembly. The following explains its technical process and characteristics with specific cases:

1. Case in Qixian, Henan: Integral Modular Hoisting

This case adopts factory-prefabricated concrete modules, ensuring component accuracy through industrial production. During construction, the prefabricated third-floor module (including walls, floor slabs, and other structures) is transported to the construction site and hoisted as a whole using a crane. The module is designed with reserved connection interfaces, which are quickly fixed to the lower structure using high-strength bolts or welding, enabling the completion of the main structure installation of a single villa (including the third floor) within 4 hours.
Technical Highlights:

• Modular Design: The third floor is prefabricated as an independent unit, reducing on-site construction procedures and improving efficiency.
• Precise Docking: The module interfaces are standardized to ensure a seamless fit with the lower structure during hoisting.
• Rapid Fixing: Rigid connections between modules are achieved through bolts or welding, ensuring structural stability.
  This mode is suitable for projects with strict deadlines but requires advance planning of transportation routes (due to the large size of the modules) and sufficient operating space for on-site crane equipment.

2. Case in South Korea: Component Assembly Construction

This case adopts a "LEGO-style" assembly process, with a more detailed construction process for the third floor:

1. Installation of the Load-Bearing System: Factory-prefabricated load-bearing columns and beams are transported to the site and hoisted to designated positions using a crane. Precise docking is achieved through a mortise-and-tenon joint (fitting of protrusions and grooves), which is then tightened and fixed with nuts.
2. Sealing Treatment: All component gaps are filled with foam sealant, and the nut areas are sealed with cement to prevent rainwater leakage and air circulation.
3. Floor Slab Construction: After backfilling with soil, a 10-centimeter-thick foam board (insulation layer) is laid, followed by dense rebar laid and bundled into a whole. Finally, concrete is poured in one go using a pump truck to form a sturdy floor slab.
   Technical Highlights:

• Mortise-and-Tenon Connection: Reduces the use of welding or bolts, improving construction speed and reducing the risk of heat-affected zones.
• Multi-Layer Protection: The foam sealant, cement sealing, and concrete pouring form a triple waterproof and moisture-proof barrier.
• Structural Reinforcement: Rebar bundling and concrete pouring enhance the floor slab's crack resistance, adapting to long-term use requirements.
  Although this mode has a longer construction period (14 days to complete the three-story main structure), it offers higher structural flexibility and is suitable for projects with complex terrain or frequent design changes.

3. Core Differences and Applicable Scenarios

The core difference between the two modes lies in the degree of industrialization and the amount of on-site work:

• Integral hoisting relies on high-level factory prefabrication and is suitable for standardized, large-scale projects;
• Component assembly allows for on-site adjustments and is suitable for scenarios with complex terrain or frequent design changes.
  Regardless of the mode, the construction of the third floor of a prefabricated house must strictly adhere to the principles of structural mechanics to ensure the strength of connection nodes and overall stability, meeting safety requirements such as earthquake and wind resistance.