Prefabricated Panels for Ridge-Roof Houses

Careful evaluation is required when using prefabricated panels for ridge-roof houses, as they have multiple limitations in terms of span, mechanics, and waterproofing. For modern house construction, cast-in-place roofs or hybrid structures are more recommended. Detailed analysis is as follows:

I. Limitations of Prefabricated Panels in Ridge-Roof Houses

1. Span Limitations
   Prefabricated panels are typically produced in 300mm modules (e.g., 2700mm, 3000mm). If the living room span of a ridge-roof house exceeds 4200mm, custom-cut panels from small workshops are needed to adjust the length. However, such non-standard panels lack quality supervision, and key parameters such as steel bar configuration and concrete strength are difficult to guarantee, making them prone to fracture or deformation due to excessive loads.

2. Mechanical Risks
   Prefabricated panels are designed for flat roofs. When laid on slopes, they need to withstand horizontal sliding forces generated by gravity. The steeper the slope, the higher the sliding risk, especially under earthquake or strong wind conditions, where panel joints are prone to cracking or even complete sliding. Additional reinforcement measures such as adding steel bar anchors and welding connectors are required, which increase construction complexity.

3. Waterproofing Defects
   The joints between prefabricated panels are weak points, and rainwater can easily leak through the splices. Traditional ridge-roof houses compensate for this defect with a double-layer structure of wooden purlins + tiled roofs: wooden purlins distribute the load, and tiles block rainwater and guide drainage. However, if prefabricated panels are laid directly, additional waterproofing membranes or coatings are required, and long-term thermal expansion and contraction can still lead to leakage.

II. Alternative Solutions and Optimization Suggestions

1. Advantages of Cast-in-Place Roofs
   A reinforced concrete cast-in-place roof forms an integral structure with the walls through steel bars, offering significantly better lateral and settlement resistance than prefabricated panels. Its span can be flexibly adjusted without the need for splices, and its waterproofing performance can be met through the density of the concrete itself and subsequent coatings. Although the cost is about 50% higher than that of prefabricated panels, its long-term safety is superior and has become the mainstream choice for rural house construction.

2. Application of Hybrid Structures
   Some regions adopt a hybrid structure of "prefabricated panels on the first floor + cast-in-place roof on the second floor": prefabricated panels on the first floor quickly enclose the space and reduce initial costs; the cast-in-place roof on the second floor enhances overall stability and avoids direct exposure of the prefabricated panels to the outside. However, attention must be paid to the load transfer between the two floors, which requires connection through structural columns or ring beams to prevent uneven settlement.

III. Historical Background and Trends

Prefabricated panels were once widely used in rural areas due to their fast construction speed and low cost (saving about half the cost compared to cast-in-place roofs). However, problems such as poor stability and easy leakage gradually emerged. For example, the collapse of a restaurant in Shanxi in 2020 drew attention due to structural defects in the prefabricated panel roof. With the upgrading of building codes, cast-in-place roofs or hybrid structures have gradually replaced prefabricated panels as the core measures to ensure house safety.