Renovation of Old Prefabricated Panel Houses
The renovation of old prefabricated panel houses requires a comprehensive approach encompassing structural assessment, construction preparation, specific renovation measures, and construction sequencing, all while strictly adhering to safety regulations.
Comprehensive structural safety assessment before renovation: Focus on inspecting the crack width at the production points of the prefabricated panels. Special treatment is required if the crack width exceeds 0.3 millimeters. Check the connection status between the prefabricated panels and the ring beams, and replace the bolts if the rust rate exceeds 30%. This step is fundamental to ensuring the safety of the renovation and can identify potential structural hazards in advance.
Construction preparation stage involves erecting a temporary support system: Set up steel pipe supports every 1.2 meters along the length of the prefabricated panels. Use H-shaped steel beams for key node replacements, with beam sections no smaller than 200200 millimeters. Simultaneously, for the panel joint positions identified during structural inspection, remove the original filling materials, implant No. 6 deformed steel bars, and pour C30 fine aggregate concrete. Add structural columns at the four corners of the house, typically with sections of 240240 millimeters, reinforced with No. 6 and No. 8 steel bars, and connected to the floor slabs. These measures enhance the overall structural stability of the house.
Specific renovation measures include roof and exterior wall treatments: After removing the original wooden roof, recast a concrete roof at the original height to ensure waterproofing, durability, and stability of the structure, while also meeting the requirements for various roofing materials. After removing the original exterior wall tiles, repaint the exterior walls and perform steel bar implantation and grouting to strengthen the load-bearing capacity and tensile properties of the original walls.
Construction sequencing should follow the principle of 'middle first, then sides': Conduct segmental demolition and cutting, maintaining symmetrical demolition, with a daily demolition volume not exceeding 30% of the total floor slab area. Continuously monitor the stress changes in the support system during demolition and prohibit the use of heavy hammer impact demolition to avoid shock and damage to the foundation structure.
It should be noted that prefabricated panel houses, born in the 1970s and 1980s, have hidden dangers such as poor thermal insulation and sound insulation, and a typical design service life of only about 40 years. In 2023, relevant departments clearly stipulated that within the scope of urban construction land, the construction of new, renovated, or expanded prefabricated panel houses and other buildings that do not comply with safety regulations is prohibited. Existing prefabricated panel houses will gradually face demolition based on actual conditions.
