Prefabricated Floor for Houses in Yibin Nanxi

Prefabricated floors were once widely used in house construction in the Yibin Nanxi area, but due to issues such as poor earthquake resistance, easy aging, and leakage, their use has been restricted by national and local authorities. Existing houses are primarily being repaired and renovated, with only dangerous buildings being demolished.

Structural Characteristics and Historical Background of Prefabricated Floor Houses

Prefabricated floor houses use prefabricated concrete slabs as their main components, including floor slabs and roof insulation layers, which are quickly assembled through splicing. This type of construction originated in the early 20th century, and many residential buildings constructed in China before 1985 adopted this structure, with a large number of such houses also present in the Yibin Nanxi area. Their advantages include short construction periods and lower costs, but design flaws have gradually emerged due to the technical standards of the time.

Core Issues with Prefabricated Floor Houses

1. Extremely Poor Earthquake Resistance
   Prefabricated slabs are connected simply (e.g., through steel bar anchoring or cement mortar filling), making them prone to separation or detachment under external forces such as earthquakes. For example, during a 5.5-magnitude earthquake in Yibin, Sichuan, rural brick-and-mortar self-built houses suffered structural instability due to weak wall bearing capacity and insecure connections of roof prefabricated slabs, exposing serious safety hazards.

2. Short Service Life and Easy Aging
   Although manufacturers claim that prefabricated slabs can last up to 50 years, in practice, issues such as aging, steel bar rusting, and concrete cracks often appear after about 10 years of use. The simple treatment of splicing gaps leads to their expansion under long-term rainwater erosion, causing floor slab cracking and leakage, which affects living safety.

3. Insufficient Overall Structural Integrity
   As independent components, prefabricated slabs lack the integrity of cast-in-place concrete, resulting in uneven floor slab bearing capacity and a tendency to break under excessive local stress. Additionally, the poor thermal insulation performance of roof prefabricated slabs can lead to excessively high indoor temperatures in summer.

National and Local Policy Restrictions

To standardize building safety, the state issued a notice on September 6, 2002, explicitly prohibiting the use of prefabricated slabs in the construction of commercial housing. Since January 1, 2005, Sichuan Province has further restricted the use of prefabricated concrete slabs as floor slabs, roof slabs, and balcony slabs. Currently, in the Yibin Nanxi area, existing prefabricated floor houses are primarily being repaired and renovated, with a focus on fixing cracks and leakage issues. Only buildings that meet the criteria for dangerous houses are being demolished to ensure the safety of residents' lives and property.

Summary

Prefabricated floor houses are widely present in the Yibin Nanxi area due to historical reasons, but their earthquake resistance, durability, and structural flaws can no longer meet modern building safety standards. The implementation of policy restrictions and repair measures aims to gradually phase out such high-risk buildings and promote the upgrading of living environments towards greater safety and durability.