Prefabricated Slabs in Commercial Housing

The use of prefabricated slabs in newly built commercial housing has been completely banned since 2003. Most existing prefabricated slab houses were constructed before 1985 and suffer from issues such as weak earthquake resistance, poor sound and thermal insulation. Current construction techniques have shifted towards safer modular and prefabricated approaches.

Core Characteristics and Historical Background of Prefabricated Slab Houses

Prefabricated slabs were commonly used floor components in early 20th-century construction, manufactured as concrete modules in factories and installed on-site. They come in two types: solid and hollow. The hollow structure achieves lightweighting by reducing non-load-bearing concrete, with typical features including parallel ceiling cracks, a clear knocking sound, a beamless and columnless structure, and possible 8-centimeter-diameter circular holes in the floor. Most of these houses were built before 1985 and, constrained by the technological conditions of the time, suffer from issues such as weak earthquake resistance, poor sound and thermal insulation, and a service life of approximately 30-50 years. Data from the Wenchuan earthquake shows that the collapse rate of cast-in-place structures was less than 5%, while prefabricated slab structures have been mandatorily phased out in areas with seismic fortification intensities above 6 degrees, highlighting their insufficient safety.

Policies and Current Status: Repair-Oriented, Demolition-Supplemented

Since 2003, the state has explicitly banned the use of prefabricated slab structures in newly built commercial housing and has instead promoted cast-in-place slab technology. In the renovation policies implemented since 2022, the treatment of prefabricated slab houses has focused on repair and renovation, with only buildings that meet the criteria for dangerous houses being demolished. This policy is based on two considerations: first, some prefabricated slab houses can have their service lives extended through reinforcement; second, large-scale demolition may cause resource waste and environmental pressure. For example, measures such as adding seismic components and improving sound and thermal insulation layers can partially enhance the safety and living comfort of these houses.

Technological Iteration: The Rise of Modular and Prefabricated Construction

Current construction techniques have shifted towards modular and prefabricated approaches, such as the E-MIC prefabricated concrete box house system introduced by China Construction First Bureau. This technology enables flexible assembly, akin to "building with LEGO blocks," through standardized factory production of prefabricated modules (including prefabricated beams and slabs), suitable for urban renewal scenarios. Unlike traditional prefabricated slab houses, modular construction offers significant advantages in terms of safety, construction efficiency, and reduction of construction waste:

• Enhanced Safety: Modules are fixed with high-strength connectors, forming an integrated load-bearing structure with seismic performance meeting cast-in-place standards;
• High Construction Efficiency: Factory prefabrication and on-site assembly proceed in parallel, shortening the construction period by more than 50%;
• Optimized Environmental Performance: Construction waste is reduced by 80%, aligning with green building development trends.

This technological iteration marks China's construction industry's transition from "extensive" to "refined" development, providing a new path for addressing the historical legacy of prefabricated slab houses.