Prefabricated Slab and Roof Construction

Prefabricated slabs were once widely used in roof construction, but they have defects in waterproofing, earthquake resistance, thermal insulation, and structural integrity. During construction, appropriate plans should be selected and reinforced according to the actual situation.

Defects of Prefabricated Slab Roofs

1. Waterproofing Issues: Prefabricated slabs are composed of multiple independent concrete panels joined together, with the panel joints being the main channels for water leakage. Even with waterproofing treatment, factors such as material aging and construction techniques can lead to rain leakage over long-term use, especially in rainy regions or after building settlement.
2. Poor Earthquake Resistance: There is a lack of effective connection between prefabricated slabs and walls, resulting in insufficient restraint on the walls and poor overall building integrity. Under external forces such as earthquakes, prefabricated slabs are prone to detachment or displacement, increasing the risk of collapse. They are not suitable for earthquake-prone areas.
3. Poor Thermal Insulation: The thickness of prefabricated slabs is usually around 12 centimeters. Concrete materials have a relatively high thermal conductivity coefficient, causing the indoor temperature to rise easily in summer and heat to dissipate quickly in winter. An additional thermal insulation layer is required to meet living comfort.
4. Weak Structural Integrity: Roofs composed of multiple panels are affected by temperature variations and building settlement, leading to panel joint cracking. Long-term use may result in a decrease in structural stability, requiring regular maintenance.

Construction Recommendations

1. When Economic Conditions Allow: Give priority to using cast-in-place concrete roofing. The cast-in-place process involves pouring concrete as a whole, significantly improving the building's integrity, earthquake resistance, and waterproofing performance while reducing long-term maintenance costs.
2. If Using Prefabricated Slab Roofs: Strengthen waterproofing treatment, such as using national standard thickened waterproof membranes for full-area laying and rigid filling reinforcement of panel joints (e.g., cement-based waterproof coatings). At the same time, thermal insulation materials (e.g., extruded polystyrene boards) or secondary roofing (e.g., color steel plates) can be placed on the prefabricated slabs to improve thermal insulation performance.
3. Optimization Plan for Two-Story Buildings: Use prefabricated slabs on the first floor to reduce costs and cast-in-place roofing on the second floor to enhance safety. This plan balances economy and structural stability, but attention should be paid to the connection treatment between the two floors to avoid cracking due to load differences.