Prefabricated Panels for Rural Flat Roofs

When using prefabricated panels for rural flat roofs, it is necessary to comprehensively consider applicable scenarios, drawbacks, key construction points, and material selection. It is recommended to prioritize cast-in-place structures when the budget allows. Detailed analysis is as follows:

Applicable Scenarios

Prefabricated panels are suitable for three types of scenarios:

1. Temporary Buildings: Short construction period, with the main structure taking only 3-7 days to build, suitable for rapid construction needs;
2. Projects with Limited Budgets: Costs are 30%-50% lower than cast-in-place structures, significantly saving on materials and labor;
3. Areas with Poor Geological Conditions: In soft soil foundations, the overall lighter weight of prefabricated panels can reduce the risk of uneven settlement.

Core Drawbacks

The following issues require special attention:

1. Poor Waterproof Performance: High probability of rain leakage, with statistics showing that 8 out of 10 households experience leakage, requiring an additional waterproof layer;
2. Insufficient Thermal Insulation: Large temperature differences between winter and summer necessitate covering the floor slab with thermal insulation materials (such as extruded polystyrene boards) or adding a suspended ceiling;
3. Low Earthquake Resistance: In earthquake zones with a magnitude of 7 or higher, steel structure reinforcement is required; otherwise, structural safety cannot be guaranteed;
4. Strict Load-Bearing Limits: The load-bearing capacity of a single panel is ≤200kg/㎡, and stacking heavy equipment or adding a second floor is prohibited.

Key Construction Points

1. Foundation Treatment: A 30cm thick gravel cushion + a 15cm plain concrete leveling layer must be laid to ensure a flat and solid base;
2. Installation Specifications: Install panels block by block from the corners of the house towards the center, using a staggered joint method to avoid structural weaknesses caused by continuous seams;
3. Joint Treatment: Fill the gaps between panels with C20 fine aggregate concrete to prevent rainwater penetration and insect infestation;
4. Waterproof Enhancement: The roof must be covered with an SBS modified asphalt waterproof layer with a thickness of ≥4mm, and additional layers should be added at corners.

Material Selection Criteria

1. Size Matching: Common dimensions are length 3-6m × width 0.5-1.2m × thickness 12-18cm, and the size should be selected according to the span;
2. Strength Requirements: The concrete strength grade should not be lower than C30 to ensure flexural load-bearing capacity;
3. Reinforcement Specifications: The diameter of the main reinforcement should be ≥8mm, with a spacing of ≤15cm; the diameter of the distribution reinforcement should be ≥6mm, with a spacing of ≤20cm.

Recommendation: If the budget allows, prioritize cast-in-place concrete roofs, which have significantly better integrity, waterproofing, and earthquake resistance than prefabricated panels, reducing long-term maintenance costs and safety hazards.