Prefabricated Components for Rural Flat Roofs

When using prefabricated components for rural flat roofs, it is necessary to comprehensively consider performance and cost. The advantages, disadvantages, and recommendations are as follows:

I. Application Characteristics and Issues of Roof Prefabricated Panels

Prefabricated panels were once a common choice for the roofs of rural self-built houses, primarily due to their low cost and fast construction speed. The hoisting of single-story or two-story houses can be completed in half a day to a day. However, their drawbacks are significant:

1. Poor waterproof performance: Gaps are easily formed at the joints of prefabricated panels, leading to a high probability of water leakage after long-term exposure to rainwater. Additional waterproof membranes or tiles are required to compensate.
2. Weak earthquake resistance: Prefabricated panels are integral hoisting structures with limited joint connection strength. In earthquake-prone areas, they are prone to cracking or collapse due to stress concentration, making them unsuitable for high-intensity earthquake zones.
3. Insufficient thermal insulation: Prefabricated panels are usually thin, resulting in poor heat insulation in summer and poor thermal insulation in winter. This can be improved by adding insulation layers (such as polystyrene boards) or covering the roof with secondary materials (such as color-coated steel sheets).

II. Structural Reliability of Connection Joints in Prefabricated Components

The load-bearing capacity of prefabricated components depends on the strength of the connection joints. Common connection methods include embedded parts, bolts, or welding. If the design is unreasonable (e.g., excessive joint spacing) or the construction is rough (e.g., bolts not tightened, welding not firm), connection failure may occur due to stress concentration or fatigue damage during long-term use, affecting the overall stability of the house. However, for one- or two-story buildings, if the joint construction quality meets the standards, their reliability is usually better than that of traditional prefabricated panel houses.

III. Advantages and Limitations of Integrated Prefabricated Concrete Houses

If the integrated prefabricated concrete house model (including roofs and walls) is adopted, its performance is significantly improved:

1. High construction efficiency: The main structure of a 200-square-meter house can be completed in only 15-20 days, with little impact from weather conditions.
2. Cost savings: Compared with traditional brick-concrete structures, costs can be saved by 15%-20%.
3. Excellent performance: Good thermal insulation performance, earthquake resistance capable of withstanding magnitude-8 earthquakes, and a service life of more than 50 years.
   However, it should be noted: These advantages are for the entire house. If only the roof uses prefabricated components, the aforementioned issues of waterproofing, thermal insulation, and earthquake resistance still need to be addressed.

IV. Recommendations and Choices

1. Prioritize cast-in-place roofs when the budget allows: Cast-in-place concrete roofs are superior to prefabricated components in terms of waterproofing, thermal insulation, and earthquake resistance, and have good integrity, making them suitable for users with high requirements for living quality.
2. Precautions when choosing prefabricated component roofs:
   • Strictly control the construction quality of connection joints, use high-strength bolts or welding, and conduct regular inspections and maintenance;
   • Accept the limitations of water leakage and poor thermal insulation, and improve them by laying waterproof layers and insulation layers;
   • Avoid using them in earthquake-prone areas or scenarios with high earthquake resistance requirements.