Renovation of Prefabricated Panel Houses

The renovation of prefabricated panel houses should be carried out comprehensively from multiple aspects, including structural safety assessment, construction treatment, problem response, and cost planning.

I. Structural Safety Assessment
Before renovation, a comprehensive structural safety inspection must be conducted, with a focus on the cracks in the prefabricated panels and their connection status. If the crack width at the production site of the prefabricated panels exceeds 0.3 millimeters, special reinforcement measures (such as implanting steel bars or carbon fiber cloth) should be taken. When the rust rate of the connecting bolts between the prefabricated panels and the ring beams exceeds 30%, they must be replaced with new bolts. In addition, the bearing capacity of the walls should be tested. If underlying hazards (such as wall hollowing or foundation settlement) are found, reinforcement treatment should be carried out in advance.

II. Key Construction Techniques

1. Roof Renovation: After removing the original wooden roof, a concrete roof should be poured without changing the original height to enhance waterproofing and structural stability, while providing a foundation for subsequent laying of various roofing materials such as tiles and photovoltaic panels.
2. Wall Treatment: After removing the original exterior wall tiles, plastering and steel bar implantation and grouting should be carried out. The depth of steel bar implantation should comply with regulations (usually 15-20 times the diameter of the steel bar), and C30 fine aggregate concrete should be poured to improve the tensile performance and load-bearing capacity of the walls.
3. Support System: Temporary supports should be erected before construction. Steel pipe supports should be set up every 1.2 meters along the length of the prefabricated panels, and H-shaped steel beams (with a cross-section of no less than 200*200 millimeters) should be used for underpinning at key nodes to ensure structural safety during demolition.
4. Panel Joints and Structural Columns: Remove the original filling materials from the panel 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, and use No. 6 and No. 8 steel bars for reinforcement, connecting them reliably with the floor slabs to improve the overall seismic performance.

III. Problem Response Strategies
Prefabricated panel houses generally have problems such as poor thermal and sound insulation, cramped space, and outdated house types. During renovation, exterior wall insulation systems (such as polystyrene board + plastering mortar) and double-glazed windows can be used to improve energy efficiency. The usable space can be expanded by removing non-load-bearing walls and optimizing the flow of movement. For the problem of aging water and electricity systems, the entire house's piping and wiring should be rearranged, using PPR pipes and flame-retardant wires to ensure safety and compliance.

IV. Cost and Common Problem Management
The renovation cost of old prefabricated panel buildings in the main urban area of Xi'an is 20%-30% higher than that of new buildings, mainly due to the costs of demolition, removal, and rearrangement of water and electricity systems. A budget should be planned in advance, and priority should be given to addressing five common problems such as the scrapping of the original water and electricity systems and the aging of bathroom waterproofing. For example, the waterproof layer should be made to a height of more than 1.8 meters, using flexible waterproof coating + tile protection. The water and electricity renovation should adopt a "horizontal and vertical" wiring layout for easy maintenance in the later stage.