Broken Cement Prefabricated Housing

Broken cement prefabricated housing poses structural safety hazards and offers a poor living experience, leading to policy-driven classification and disposal methods, including demolition and renovation.

Structural Safety Hazards

1. Joint Issues: Prefabricated panels are bonded with cement mortar, which tends to crack and crumble over time, causing panel looseness, floor vibration, and water leakage.
2. Weak 'Skeleton': Most prefabricated panels are hollow structures with thin and sparse internal steel bars, resulting in poor earthquake resistance. Daily use, such as placing heavy objects (e.g., wardrobes), may cause floor cracks.
3. Meeting Dangerous Building Standards: If the crack width in load-bearing walls exceeds 1 centimeter, concrete peels off with severely rusted steel bars (crumbly upon squeezing), door and window frames are deformed and cannot be closed, or foundation settlement causes building vibration (e.g., slight vibration during heavy rain), the building is classified as a D-grade dangerous building. Renovation costs may exceed reconstruction costs, necessitating demolition. For example, a four-story prefabricated panel building in Beihu District, Chenzhou City, was judged as a dangerous building at risk of collapse due to roof脱落 (falling off), wall inclination and cracking, and foundation settlement.

Poor Living Experience

1. Water Leakage: As the mortar in the joints of prefabricated panels ages, rainwater easily seeps into the interior, particularly affecting top-floor residents who need containers to catch water.
2. Poor Sound Insulation: The insufficient thickness of prefabricated panels and the presence of long circular holes allow sound to penetrate easily, with noise from neighboring units being amplified through the holes.
3. Cold in Winter and Hot in Summer: Prefabricated panels have poor thermal insulation properties, resulting in low indoor temperatures in winter and sweltering heat in summer.

Policy-Driven Classification and Disposal

1. Buildings to be Demolished:
   • D-Grade Dangerous Buildings: Directly demolished and rebuilt.
   • Planned Acquisition: Demolition required for urban development (e.g., subway construction, school building), with compensation standards varying by project.
   • Risk Aversion Relocation: Buildings located in earthquake zones, landslide-prone areas, or low-lying areas prone to flooding during the flood season are relocated by the government.
2. Buildings Eligible for Renovation: Renovated through old residential area renovation projects ("old renovation"), such as exterior wall insulation, replacement of aging pipelines, and elevator installation, with partial government subsidies provided.