Prefabricated Floor Panels for Houses
Prefabricated floor panels for houses were commonly used in early 20th-century construction as floor slabs. They are engineering modules or panels produced in prefabrication yards and transported to the site for installation.
Types and Structures
Prefabricated panels come in two main types: solid and hollow. The hollow structure achieves lightweighting by reducing non-load-bearing concrete. During production, a hollow mold is first made using wooden planks. Reinforcing bars are placed inside the mold, and cement is poured in. After drying, the wooden planks are knocked off to form the panel. This design reduces weight while maintaining structural strength, making it suitable for scenarios with low load requirements.
Dimensions and Specifications
- Span: The maximum span for residential prefabricated panels is 4.2 meters; longer spans require customization. Lengths generally increase in 300mm increments, such as 3000mm and 3300mm, with special sizes like 3800mm and 4000mm also available for customization.
- Width: The primary widths are 500mm and 600mm, catering to different architectural layout needs.
- Thickness: Common thicknesses are 120mm and 150mm, with increased thickness enhancing load-bearing capacity.
- Load Ratings: Residential panels typically come in Grade I (live load 1kN/m²) and Grade II (live load 2kN/m²). In the southwest region, the minimum requirement is Grade IV (live load 4kN/m²) to accommodate geological conditions or special usage needs.
Application Scenarios
Prefabricated panels were widely used for low-rise residential floor slabs, highway ditch covers, and roof insulation layers due to their low cost and fast construction. For example, they are commonly used as floor-separating components in rural self-built houses, and highway ditch covers often adopt prefabricated panels for easy maintenance.
Limitations
- Low Structural Strength: Poor overall integrity and weak seismic performance make them prone to cracking or collapse during earthquakes.
- Insufficient Durability: With a service life of approximately 30-50 years, they are far less durable than cast-in-place concrete structures, often leading to wall cracks and water leakage in later stages.
- Poor Thermal Insulation: Although the hollow structure reduces weight, it also results in inadequate thermal insulation, requiring additional insulation layers.
Modern Alternatives and Policies
With advancements in construction technology, cast-in-place concrete and prefabricated buildings are gradually replacing prefabricated panel houses. Cast-in-place concrete offers better overall integrity and seismic resistance, while prefabricated buildings enhance efficiency through factory-produced components. Since 2022, China has implemented renovation policies for old buildings, focusing on repairing and upgrading prefabricated panel houses and only demolishing those that meet hazardous building standards to balance safety needs with resource utilization.
