Renovation of Prefabricated Slabs in Old Houses

The renovation of prefabricated slabs in old houses can be carried out through reinforcement renovation or original demolition and reconstruction, as detailed below:

Reinforcement Renovation

1. Pre-renovation Assessment: A comprehensive structural safety assessment is required, focusing on inspecting the width of cracks in the prefabricated slabs. If the crack width exceeds 0.3 millimeters, special treatment measures must be taken; simultaneously, the connection status between the prefabricated slabs and the ring beams should be inspected, and new bolts should be replaced if the bolt corrosion rate exceeds 30%.
2. Construction Preparation: A temporary support system should be erected, with steel pipe supports placed every 1.2 meters along the length of the prefabricated slabs. Key nodes should be supported using H-shaped steel beams, with the beam section needing to be ≥200×200 millimeters, to ensure structural stability during construction.
3. Slab Joint Treatment: Remove the original filling material, implant No. 6 deformed steel bars, and pour C30 fine aggregate concrete to enhance the connection strength of the slab joints; add structural columns at the four corners of the house, typically with a section of 240×240 millimeters, using No. 6 and No. 8 steel bars for reinforcement, and reliably connect them to the floor slab to improve overall seismic performance.
4. Construction Sequence: Follow the principle of 'middle first, then sides,' carrying out segmental demolition and cutting while maintaining symmetrical demolition. The daily demolition volume should not exceed 30% of the total floor slab area. During demolition, continuously monitor the stress changes in the support system, and prohibit the use of heavy hammers for impact demolition to avoid shock and damage to the foundation structure.

Original Demolition and Reconstruction

1. Policy Support: Some regions are piloting the 'self-renewal, original demolition and reconstruction' policy, allowing old houses to increase their new floor plan or actual usable area by up to about 30% after scientific planning, thereby improving living space utilization.
2. Reconstruction Method: Original demolition and reconstruction is not simply a replication of the original structure but involves demolishing it and then laying new foundations and designing modern building structures. For example, elevators can be added to provide direct access to each household, optimizing lighting and dynamic-static zoning to replace the original dark and cramped layout; water, electricity, gas, and heating pipelines can be laid underground and rearranged to eliminate safety hazards such as pipeline aging.

Suggestions for Choosing Between the Two Methods: If the original house structure has minor damage and the original layout needs to be retained, reinforcement renovation is more economical; if the house is severely aged or requires a significant improvement in living quality, original demolition and reconstruction are more advantageous. Before renovation, a comprehensive decision should be made based on the actual condition of the house, policy requirements, and budget.