Renovation of Prefabricated Panel House Roofs
The renovation of prefabricated panel house roofs requires a scientific plan tailored to the current condition of the house, with key points including structural safety assessment, waterproofing renovation, material upgrading, load reinforcement, and standardized construction, while also complying with policy guidelines.
1. Structural Safety Assessment as a Prerequisite for Renovation
Before renovation, a professional agency should be commissioned to conduct a comprehensive inspection of the prefabricated panel roof, focusing on the crack width at the joints of the prefabricated panels (if exceeding 0.3 millimeters, epoxy resin grouting or carbon fiber reinforcement should be used) and the connection status between the prefabricated panels and the ring beams (if the bolt corrosion rate exceeds 30%, they should be replaced with stainless steel bolts). For example, during the renovation of an old residential community, some prefabricated panels were found to have hidden cracks due to long-term load-bearing. After being located through ultrasonic testing, pressure grouting technology was used for repair, avoiding the risk of structural instability.
2. Systematic Waterproofing Renovation
The joints between prefabricated panels are high-risk areas for leakage and require a combined solution of 'base repair + panel joint reinforcement + full-area waterproofing'. Specific steps include: removing debris from the joints, filling the joints with cement-based rigid waterproofing material until full; laying national standard thickened SBS modified asphalt membrane, with special emphasis on strengthening nodes such as ridges and gutters; finally, applying a 2-millimeter-thick polyurethane waterproof coating to form a protective layer. The Zhonghuan Jiayuan project in Putuo District, Shanghai, resolved a decade-long water seepage problem through this solution and provided a 5-year warranty.
3. Roof Material Upgrading Considering Structure and Function
If the original roof is made of wood or lightweight materials, it can be demolished and replaced with a reinforced concrete roof (recommended thickness of 80-100 millimeters), which not only enhances waterproofing performance but also provides a foundation for subsequent laying of materials such as ceramic tiles and metal panels. During renovation, it is necessary to ensure that the slope of the new roof is not less than 3% for drainage purposes; if additional loads such as solar equipment are to be added, structural rechecking should be carried out in advance.
4. Load Reinforcement Measures to Ensure Long-Term Safety
During renovation, the load-bearing capacity of the walls needs to be strengthened: when repainting after demolishing the exterior walls, planting bar technology (with steel bars of 10 millimeters in diameter and a spacing of 500 millimeters) should be used, and high-strength non-shrink grouting material should be poured in; 240*240 millimeter constructional columns should be added at the four corners of the house, with 4 longitudinal steel bars of 12 millimeters in diameter configured inside, and connected to the floor slab through tie bars to form an overall load-bearing system.
5. Construction Specification Requirements to Ensure Process Safety
During the demolition phase, a temporary support system should be erected (setting steel pipe supports every 1.2 meters along the length of the prefabricated panels, with a spacing between upright posts of no more than 1 meter), and the principle of segmented symmetrical demolition should be adopted (the daily demolition amount should not exceed 30% of the total floor area), with the use of heavy hammers for impact demolition prohibited to avoid foundation settlement. During construction, safety warning signs should be set up, and full-time safety officers should be assigned for supervision.
6. Policy Guidelines Clarifying Renovation Boundaries
According to the 2022 old residential renovation policy, the renovation of prefabricated panel houses is based on 'repair as the main approach and demolition as a supplementary measure', with only buildings identified as Grade D dilapidated houses being subject to demolition and reconstruction. Renovation should simultaneously improve facilities such as fire protection and barrier-free access to enhance living functions, while strictly controlling building height and floor area ratio to ensure harmony with the surrounding environment.
