Prefabricated Panels for Self-Built House Roofs

There are numerous issues with using prefabricated panels for the roofs of self-built houses. If economic conditions permit, it is recommended to use cast-in-place concrete for roofing; if prefabricated panels must be used, it is essential to strictly evaluate geological and climatic conditions and strengthen treatment measures.

I. Main Issues with Prefabricated Panels

1. Joint Cracking and Waterproofing Risks
   Prefabricated panels are manufactured in separate pieces, and during assembly, joints are prone to cracking due to material shrinkage, construction errors, or foundation settlement. Waterproofing is challenging, as traditional asphalt or waterproofing membranes often fail to fully seal the gaps, leading to a high probability of leaks. There is even a saying among the public that '8 out of 10 houses leak.'
2. Poor Earthquake Resistance
   Prefabricated panels are not integrally connected to the walls and lack reinforcement measures such as tie bars. During earthquakes, they are prone to detaching from the walls or even collapsing. In earthquake-prone areas, their structural safety is significantly lower than that of cast-in-place roofs.
3. High Risk of Geological Disasters
   In the event of geological disasters (such as landslides or mudslides) or uneven foundation settlement, prefabricated panels, due to their poor integrity, are prone to forming through cracks, exacerbating the risk of damage to the house.
4. Insufficient Thermal Insulation
   Prefabricated panels have limited thickness and conduct heat quickly, resulting in poor thermal insulation in both summer and winter. Additional insulation layers (such as foam boards) or covering materials like tiles are required to improve performance, increasing costs and construction complexity.

II. The Only Advantage of Prefabricated Panels
Prefabricated panels are inexpensive and have a short construction period. For example, for a 40-50 square meter roof, the total cost is approximately 800 yuan (including hoisting), making them suitable for scenarios with tight budgets or urgent completion needs.

III. Recommendations for Use

1. Prioritize Cast-in-Place Roofs
   Cast-in-place concrete roofs offer strong integrity, excellent earthquake resistance, waterproofing, and thermal insulation, with lower long-term costs. They are a safer and more durable choice.
2. Precautions When Using Prefabricated Panels
   • Strictly Evaluate Conditions: Ensure that the house is located in an area with stable geology, low earthquake risk, and dry climate (to reduce rain erosion).
   • Strengthen Joint Treatment: Use high-strength waterproof mortar for filling joints and lay two layers of waterproofing membranes, with additional layers at the joints.
   • Add Structural Measures: Install tie bars at the connections between prefabricated panels and walls to enhance integrity; if there is a high risk of foundation settlement, reinforce the foundation in advance.
   • Optimize Thermal Insulation Design: Lay high-efficiency insulation materials such as extruded polystyrene boards on the prefabricated panels and then cover with a protective layer.