Housing Hollow Slab and Prefabricated Slab

The hollow structural concrete slab used in houses built with prefabricated slabs as the main components is known as housing hollow slab and prefabricated slab.

I. Definition and Production The hollow slab reduces the amount of concrete in non-load-bearing parts through a hollow cross-sectional design, achieving lightweighting. The prefabricated slab is a factory-made component. During production, a hollow model is first nailed together using wooden planks. Reinforcing bars are then placed in the hollow part of the model, and cement is poured in. After drying, the wooden planks are knocked off to form the finished product. There are two types: solid and hollow. The hollow structure enhances performance by optimizing material distribution.

II. Development History Domestic prefabricated slab technology began with non-prestressed hollow slabs in the 1950s. In the early 21st century, the U.S. SP prestressed hollow slab technology was introduced. The release of the national standard atlas for Prestressed Concrete Hollow Slabs (EHC Slabs) in March 2025 marked a technological upgrade. EHC slabs adopt an extrusion molding process, with a maximum span of 20 meters, significantly improving structural performance.

III. Core Advantages

1. Lightweighting and Construction Convenience: Compared to solid slabs of the same span, the weight is reduced by 30%-50%, and the building height is lowered by 10%-15%, facilitating transportation and installation, especially suitable for small-span bridges.
2. Structural Performance Optimization: Cast-in-place concrete hollow floors can reduce the structural self-weight by 20%-30%, increase floor stiffness by 15%-20%, and shorten the construction period by more than 30%. Prefabricated prestressed hollow slabs have a 40% increase in load-bearing capacity, a span increased to 18 meters, a 25% reduction in self-weight, and a 1.5-fold improvement in seismic performance.
3. Economy and Durability: The hollow design saves 20%-30% of concrete usage, reducing overall costs by 15%-20%. The structural lifespan exceeds 50 years, and the load-bearing capacity is not weakened by hollowing.

IV. Application Scenarios It covers residential, commercial, educational, medical, and industrial building fields, specifically including:

• Auxiliary structures such as highway ditch covers and roof insulation layers;
• Floor systems in large-span public buildings (e.g., stadiums, convention centers);
• Prefabricated floor systems in multi-story residential buildings.

V. Renovation and Transformation Restrictions

1. Ceiling Construction Specifications: The fixing frame must be positioned at solid parts, using expansion screws for light pressure fixation. The wall surface should use light steel keels as a base, with a preference for 2-centimeter-thick gypsum boards. The horizontal line must be calibrated before construction.
2. Seismic Zone Restrictions: In areas with a seismic fortification intensity of 7 degrees or higher, it is recommended to adopt a suspended ceiling design or forgo ceiling installation to avoid structural safety hazards.

VI. Current Situation and Policy Orientation With the popularization of cast-in-place concrete and prefabricated building technologies, traditional prefabricated slab houses are gradually being replaced. The 2022 renovation policy clearly states that prefabricated slab houses should be primarily repaired and renovated, with only buildings identified as D-grade dilapidated houses being demolished. Existing prefabricated slab houses generally have problems such as weak seismic performance (seismic fortification intensity of only 6 degrees), poor sound insulation and thermal insulation (weighted sound insulation level < 45 dB, heat transfer coefficient > 2.0 W/(㎡·K)), and a lifespan nearing its end (30-50 years). Some regions have initiated systematic demolition and reconstruction work.