Prefabricated Panels for First-Floor Houses

For first-floor houses, the use of prefabricated panels can achieve moisture-proofing through an elevated floor structure, following the principle of 'trading space for dryness.' Specifically, a 30-50 cm cavity is left between the foundation and the floor, allowing underground moisture to dissipate within the cavity and preventing the floor from becoming damp.

Principle and Implementation Points of Moisture-Proofing with Elevated Prefabricated Panel Floors

The core of moisture-proofing with elevated prefabricated panel floors lies in blocking the upward path of underground moisture. During implementation, after the ground beam is poured, the height of the backfill soil should be controlled to be 30-50 cm from the floor and compacted to form a cavity layer. When moisture rises to the cavity, due to the open space and air circulation with the outside, the humidity gradually decreases, preventing it from continuing to rise to the indoor floor, thus effectively achieving moisture-proofing. This method is suitable for low-rise buildings in areas with high groundwater levels or high humidity, especially for first-floor houses without basements, where the effect is particularly significant.

Characteristics and Historical Applications of Prefabricated Panels

Prefabricated panels are cement components pre-fabricated in factories. During production, wooden models are nailed together, steel bars are arranged, and cement is poured to form the panels, which are divided into solid and hollow types. The hollow structure achieves lightweighting by reducing non-load-bearing concrete, lowering transportation and installation costs. This technology originated in the early 20th century and was widely used in scenarios such as floor slabs and roof insulation layers. Most residential buildings constructed in China before 1985 adopted this type of structure. However, existing prefabricated panel houses generally suffer from issues such as weak earthquake resistance and poor sound and thermal insulation, with a service life of about 30-50 years, requiring regular inspection and maintenance.

Governance Policies and Safety Assessments for Prefabricated Panel Houses

According to the State Council's '15th Five-Year Plan for Urban Renewal,' China will renovate more than 500,000 sets (units) of non-complete housing, including prefabricated panel houses, with a focus on promoting seismic reinforcement in earthquake-prone areas. House safety assessments are divided into four grades: A, B, C, and D:

• Grade A or B: The main structure has no major issues, and living conditions are improved through the renovation of old residential areas;
• Grade C: The house is dilapidated but has repair value and requires repair and reinforcement;
• Grade D: The house is overall dangerous and needs to be demolished and rebuilt, with expropriation and demolition depending on the implementation of regional planning projects.

The moisture-proofing and renovation of prefabricated panel houses should be combined with structural characteristics and policy requirements, prioritizing measures such as elevated floor moisture-proofing and repair and reinforcement to extend their service life, while paying attention to policy dynamics to reasonably plan disposal paths.