Renovation of Houses with Hollow Prefabricated Floor Slabs

The renovation of houses with hollow prefabricated floor slabs should follow a scientific process, ensuring safety and effectiveness through professional assessment, targeted plan formulation, meticulous construction, and strict precautions.

1. Pre-renovation Assessment

Before renovation, a professional team should be commissioned to conduct a comprehensive structural safety assessment, focusing on the following indicators:

• Prefabricated slab cracks: Check the width of cracks at the manufacturing points. If they exceed 0.3 millimeters, special treatment (such as grouting reinforcement or steel plate reinforcement) is required.
• Connection status: If the bolt corrosion rate between the prefabricated slabs and the ring beams exceeds 30%, they must be replaced to avoid connection failure leading to structural instability.
• Overall stability: Professional testing should be conducted to determine whether the house requires reinforcement or demolition. According to data from the Ministry of Housing and Urban-Rural Development, approximately 60% of old prefabricated slab buildings nationwide can be reinforced after assessment, saving resources and extending their lifespan.

2. Renovation Plan Formulation

Formulate a “one-house-one-plan” approach based on the assessment results:

• Wall cracks: Minor cracks should be repaired with grouting; severe cracks require steel plate reinforcement, along with repainting the exterior walls and grouting with steel bars to enhance load-bearing strength.
• Roof leakage: Remove the original wooden roof and pour a new concrete roof to enhance waterproofing and structural stability, providing a foundation for subsequent roofing material installation.
• Unstable foundation: Reinforce the foundation by piling to prevent settlement risks.
• Sound insulation optimization: Use soundproof panels and double-glazed windows to improve sound insulation by approximately 70%, enhancing living comfort.

3. Specific Renovation Measures

• Roof renovation: Pour a concrete roof without changing the original height to ensure waterproofing and structural durability, while meeting the needs for diverse roofing material installation.
• Wall renovation:
  • Remove the original filling material at the slab joints, implant No. 6 threaded steel bars, and pour C30 fine aggregate concrete;
  • Add structural columns (with a cross-section of 240*240 millimeters) at the four corners of the house, combined with No. 6 and No. 8 steel bars for reinforcement and connection to the floor slabs to enhance overall earthquake resistance.
• Sound insulation treatment: Install soundproof panels inside the walls and replace windows with double-glazed ones to effectively block noise transmission.

4. Construction Precautions

• Temporary support system: Set up steel pipe supports every 1.2 meters along the length of the prefabricated slabs, and use H-shaped steel beams with a cross-section of no less than 200*200 millimeters for key nodes to prevent structural collapse during demolition.
• Construction sequence: Follow the principle of “middle first, then sides,” demolishing in segments symmetrically. The daily demolition volume should not exceed 30% of the total floor slab area, and the stress changes in the support system should be monitored in real-time.
• Construction method: Prohibit the use of heavy hammer impact for demolition to avoid shock damage to the foundation. Prioritize cutting or static demolition techniques.