Processing Flowchart for Prefabricated Panel Houses

The processing flow for prefabricated panel houses can be divided into six key steps: structural inspection, load verification, plan determination, construction preparation, demolition and reinforcement, and acceptance and renovation, as detailed below:

1. Structural Inspection and Appraisal
It is necessary to entrust a qualified inspection agency to conduct a comprehensive 'check-up' of the house, focusing on whether the lap length of the prefabricated panel ends on the wall (beam) meets the specifications (generally ≥80mm), and whether there are severe cracks or exposed rebar at the bottom of the panels. Inspect the concrete strength, rebar position and corrosion, panel joint width (special treatment required if exceeding 0.3mm), wall perpendicularity, and foundation settlement. For example, if the corrosion rate of the connecting bolts between the prefabricated panels and the ring beam exceeds 30%, they need to be replaced during subsequent construction.

2. Load Verification and Plan Justification
Based on the intended use after renovation (such as adding partition walls or equipment rooms), recalculate the dead and live loads on the floor and verify the load-bearing capacity of the existing walls, columns, and foundations. Special attention should be paid to the impact of the self-weight of cast-in-place panels (usually slightly heavier than prefabricated panels, with a thickness of 120-150mm) on the walls or foundations. If the load-bearing capacity is insufficient, a reinforcement plan should be developed simultaneously.

3. Plan Comparison and Selection

• Retain the Composite Layer: Directly add a cast-in-place composite layer on the prefabricated panels, causing minimal damage and suitable for houses in good structural condition.
• Combined Reinforcement: Adopt a 'prefabricated panel + cast-in-place strip' plan, using cast-in-place concrete strips to 'lock' the dispersed prefabricated panels into a whole, improving overall integrity.
• Wall Removal and Beam Replacement: Demolish the original structure and recast the concrete roof, adding structural columns (commonly used in the renovation of 30-year-old prefabricated panel houses), suitable for houses with severe structural aging or complete functional changes.

4. Construction Preparation and Support System Setup
Set up steel pipe supports every 1.2 meters along the length of the prefabricated panels, and use H-shaped steel beams for key node underpinning (beam section ≥200*200mm) to ensure structural stability during demolition. Simultaneously, conduct a secondary inspection of the connection status between the prefabricated panels and the ring beam to avoid collapse due to connection failure.

5. Demolition and Reinforcement Construction

• Demolition Phase: Demolish in sections following the principle of 'middle first, then sides', with a daily demolition volume not exceeding 30% of the total floor area, and continuously monitor the stress changes in the support system. Do not use heavy hammers for impact demolition.
• Panel Joint Treatment: Remove the original filling material, implant No. 6 threaded rebar, and pour C30 fine aggregate concrete to enhance panel joint connections.
• Wall Reinforcement: Perform rebar planting and grouting on the exterior walls, add structural columns (section 240*240mm) and connect them to the floor to improve wall stability.

6. Acceptance and Subsequent Treatment
Each construction phase requires cooperation with the owner for acceptance to ensure scientificity; conduct overall waterproofing, painting, and other renovation work after the renovation is completed. Precautions: Professional structural appraisal must be prioritized for old house renovations, and the budget should include 10%-20% more contingency funds than for a new house of the same area to address hidden engineering issues.