How to Lay Prefabricated Floor Slabs on Building Floors

The laying of prefabricated floor slabs in buildings should be carried out by selecting the direction based on the span, structural requirements, and specifications, and strictly following the construction process. The specific steps are as follows:

I. Selection of Laying Direction

1. Horizontal Layout Method
   Suitable for conventional buildings (such as residential houses and apartments), where the floor slabs are laid horizontally. Priority should be given to horizontal construction in the short-span direction. For example, when the north-south span of a room is greater than the east-west span, the floor slabs should be laid in the east-west direction to shorten the load-bearing span of individual slabs, reduce pressure, and minimize the risk of foundation settlement.
2. Oblique or Staggered Layout Method
   • Oblique Layout: Used for special structures such as pitched roofs and irregular spaces, requiring professional equipment support.
   • Staggered Layout: Enhances stiffness and seismic performance by staggering the arrangement of floor slabs. Suitable for earthquake-prone areas or large public buildings, it can strengthen the overall structural integrity.

II. Construction Process

1. Preliminary Preparations
   • Technical Preparations: Verify the construction drawings and slab layout plans, confirm the model, quantity, and position of the slabs; transfer benchmark points and mark elevation control lines.
   • Material Inspection: Check the prefabricated slabs' certificates of conformity and concrete strength reports to ensure there are no cracks, chipped corners, or other defects; dimensional deviations must comply with specifications (e.g., length deviation ≤ ±10mm).
   • Stacking Requirements: Handle with care during lifting and stacking, align the wooden supports above and below the stack, and keep the height of the stack no more than three layers.
2. Laying Operations
   • Installation Sequence: Lift and install the slabs according to the slab layout plan, ensuring the end support length is ≥ 120mm and the slab joint width is controlled between 20-50mm.
   • Leveling and Fixing: Adjust the slab surface elevation with a level gauge, fill the slab joints with C35 fine aggregate concrete (mixed with a micro-expansion agent), and level the supports with M15 cement mortar.
   • Reinforcement Measures: Install tie bars (e.g., Φ8mm @ 500mm) in the slab joints to enhance overall integrity.
3. Post-Laying Treatments
   • Waterproofing: Lay 3mm thick SBS modified asphalt waterproofing membrane on the roof and seal the slab joints with neutral silicone weather-resistant sealant.
   • Protective Layer Construction: Pour a 40mm thick C20 fine aggregate concrete protective layer with embedded steel mesh to prevent cracking.

III. Key Considerations

1. Span Control: The direction of the floor slabs must align with the short span to prevent cracking due to excessive span.
2. Load Requirements: Design considerations must include live loads (e.g., roof live load of 2.0kN/m²) and long-term pressure distribution.
3. Seismic Requirements: In earthquake-resistant areas (e.g., with a seismic design intensity of 7 degrees), staggered layouts or additional tie bars should be prioritized.
4. Material Quality: Strictly inspect prefabricated slabs and auxiliary materials to ensure compliance with national standards (e.g., GB50345, GB50204).

By scientifically selecting the laying direction, standardizing the construction process, and strengthening control over key nodes, the load-bearing capacity, flatness, and durability of the prefabricated floor slabs can be effectively ensured.