Renovation of Prefabricated Panel Houses for Bungalows

The renovation of prefabricated panel houses for bungalows requires comprehensive treatment in terms of structural safety, roofing, exterior walls, and more, as detailed below:

1. Structural Safety Assessment and Treatment
Before renovation, a comprehensive structural safety assessment must be conducted, focusing on inspecting the width of cracks in the prefabricated panels. If the crack width exceeds 0.3 millimeters, special treatments such as pressure grouting or carbon fiber reinforcement are required. Additionally, the connection status between the prefabricated panels and the ring beams should be inspected. If the bolt corrosion rate exceeds 30%, the bolts should be replaced with stainless steel or hot-dip galvanized bolts to ensure connection stability.

2. Roof Renovation
It is recommended to completely remove the original wooden roof and, while maintaining the original building height, recast a concrete roof. The concrete roof should be equipped with a double-layer, bidirectional steel reinforcement mesh (with a diameter of no less than 8 millimeters) and include division joints (with a spacing of no more than 6 meters) to enhance waterproofing performance and structural stability. After renovation, the roof can be covered with various materials such as tiles, metal panels, or photovoltaic panels.

3. Exterior Wall Treatment
After removing the original exterior wall tiles, two key processes are required: first, repaint with high-elasticity waterproof coating with a thickness of no less than 2 millimeters; second, perform steel bar implantation and grouting treatment by implanting No. 6 threaded steel bars every 500 millimeters along the wall height, with a spacing of 300 millimeters, and pouring C30 fine aggregate concrete to enhance the wall's load-bearing strength and tensile properties.

4. Support System Construction
During the construction preparation phase, a temporary support system must be erected: steel pipe supports (with a diameter of no less than 48 millimeters) should be placed every 1.2 meters along the length of the prefabricated panels, with key nodes using H-shaped steel beam underpinning (with a cross-section of no less than 200*200 millimeters) and fixed to the original structure with bolts. The support system must be calculated and checked to ensure it can withstand 1.5 times the construction load.

5. Panel Joint Treatment
At the locations of panel joints identified during structural inspection, the original joint filling material should be removed to one-third of the panel thickness, No. 6 threaded steel bars (with a spacing of 200 millimeters) should be implanted, and then C30 fine aggregate concrete should be poured and vibrated densely. The surface of the panel joints should be waterproofed by applying two coats of polyurethane waterproof coating.

6. Addition of Structural Columns
Structural columns should be added at key locations such as the corners of the house and stairwells, generally with a cross-section of 240*240 millimeters. The longitudinal reinforcement should use No. 6 and No. 8 steel bars (with a reinforcement ratio of no less than 0.8%), and stirrups should be spaced at 200 millimeters. The columns should be connected to the floor slab through steel bar implantation to form an overall load-bearing system.

7. Construction Sequence and Monitoring
The principle of 'middle first, then sides' should be adopted for segmented demolition, with the daily demolition amount not exceeding 30% of the total floor area. During demolition, the stress changes in the support system should be monitored in real-time (using strain gauges), and the use of heavy hammers for impact demolition is prohibited to avoid shock and damage to the foundation structure.

8. Overall Renovation Approach
According to the 2026 urban renewal policy, the renovation method should be comprehensively determined based on the house's safety condition, assessment results, area conditions, and residents' wishes: D-grade dilapidated houses should be prioritized for demolition and reconstruction; C-grade dilapidated houses can undergo repair and reinforcement; and non-complete housing can be promoted for original demolition and reconstruction or functional improvement renovation.