Renovation of House Prefabricated Slabs to Cast-in-Place Construction

The renovation of house prefabricated slabs to cast-in-place construction should be carried out with caution. It requires professional structural assessment and the selection of a reasonable plan. Common methods include adding a composite layer or demolition and reconstruction, with the latter having higher risks.

Reasons for Renovation

Prefabricated slabs have issues such as poor integrity, insufficient load-bearing capacity, and restricted functionality. Their slab joints are prone to water leakage, they have poor sound insulation, and weak earthquake resistance, making it difficult to meet the safety and comfort requirements of modern buildings. For example, when the end lap length of the prefabricated slab is insufficient (the specification requires ≥ 80mm), the overall structural integrity is further reduced, posing safety hazards.

Pre-renovation Inspection and Assessment

1. Structural Inspection: It is necessary to inspect the concrete strength, the position and corrosion of steel bars, with a focus on checking whether the end lap length of the prefabricated slabs meets the standards and whether there are serious cracks or exposed steel bars at the slab bottom.
2. Load-bearing Capacity Review: Based on the post-renovation usage function (such as increased loads), review the load-bearing capacity of the original walls, columns, and foundations. If insufficient, it is necessary to reinforce the walls or foundations simultaneously to avoid structural damage caused by increased loads.

Mainstream Renovation Plans

1. Adding a Cast-in-Place Composite Layer:
   • Method: Retain the original prefabricated slabs and directly pour a cast-in-place concrete layer (usually with a thickness of 50 - 80mm) on top to form a composite structure.
   • Advantages: Minimal damage, a relatively short construction period, relatively low cost, and a significant improvement in the overall integrity and load-bearing capacity of the floor slab.
   • Applicable Scenarios: Houses with relatively minor damage to the prefabricated slabs and structures that basically meet the requirements.
2. Complete Demolition of Prefabricated Slabs and Reconstruction:
   • Method: Completely demolish the original prefabricated slabs, re-tie the steel bars, and pour cast-in-place floor slabs.
   • Risks: The demolition process may damage the surrounding structures (such as walls and beams), leading to a decrease in the stability of the house. Temporary support measures are required.
   • Applicable Scenarios: Houses with severely damaged prefabricated slabs or those requiring a complete renovation, but strict structural safety assessments are necessary.

Precautions

1. Professional Justification: Renovation should be carried out on the basis of structural assessment and expert justification to avoid safety accidents caused by blind construction.
2. Cost and Construction Period: Cast-in-place renovation has high costs, a long construction period, and significant disturbance to the house. Funds and time need to be planned in advance.
3. Construction Specifications: During the construction of the composite layer, it is necessary to ensure a firm bond between the new and old concrete. During demolition and reconstruction, steel bars should be tied and formwork should be set up strictly in accordance with the specifications.

Summary: When renovating prefabricated slabs to cast-in-place construction, structural safety should be the core consideration. Priority should be given to the plan of adding a composite layer. If demolition and reconstruction are necessary, professional teams should be entrusted to operate, and the stability of the house should be monitored throughout the process.