Prefabricated Panels for Rural Flat Roofs

The use of prefabricated panels for rural flat roofs was once common, but issues such as joint cracking, poor waterproofing, inadequate insulation, and low earthquake resistance have led to their gradual replacement by solutions like cast-in-place concrete roofs.

Joint Cracking and Leakage Issues

Prefabricated panels are prefabricated components that require splicing during installation, with the joints between two panels being structural weak points. Affected by temperature changes, building settlement, or material aging, joints are prone to cracking, leading to rainwater leakage. In rural areas, there was once a saying that '8 out of 10 households experience leaks,' reflecting the prevalence of this issue. Even with repairs using asphalt or waterproof coatings, cracks may reappear repeatedly due to continuous stress at the joints, making it difficult to achieve a permanent solution.

Poor Waterproofing Performance

The waterproofing of prefabricated panel roofs relies on surface coatings or covering materials, but the structure itself does not possess waterproofing capabilities. Traditional waterproofing methods (such as laying felt or applying waterproof paint) often fail due to improper construction, material aging, or joint cracking. For example, felt can become brittle and detach under prolonged exposure to sunlight and rain, while waterproof paint may develop blisters due to an uneven base layer, allowing rainwater to penetrate. Multiple repairs not only increase costs but may also damage the roof structure.

Inadequate Insulation Performance

Prefabricated panels are typically about 12 centimeters thick and, although hollow, offer limited heat insulation and retention capabilities. In summer, direct sunlight raises the roof surface temperature, rapidly transferring heat indoors and making the interior stuffy; in winter, poor insulation causes indoor heat to dissipate easily, necessitating additional coal burning or electric heating devices. To address this issue, some farmers add a secondary roof made of a mixture of slag, lime, and cement on top of the prefabricated panels, increasing construction complexity and the building's load.

Low Earthquake Resistance

Prefabricated panels are connected to the main building structure with a small amount of rebar or mortar, resulting in poor overall integrity and a low earthquake resistance coefficient. Under seismic forces, joints are prone to breaking, and panels may detach or shift, potentially leading to building collapse. Therefore, regions prone to earthquakes have explicitly restricted the use of prefabricated panel roofs, opting instead for cast-in-place reinforced concrete roofs to enhance structural stability through monolithic pouring.

Advantages of Alternative Solutions

Currently, rural roofing materials are undergoing gradual upgrades: cast-in-place concrete roofs, although more expensive, resolve issues related to joints, waterproofing, and earthquake resistance through monolithic reinforced concrete pouring, while offering superior insulation performance; color-coated steel roofs are quick to install and provide excellent waterproofing, suitable for temporary buildings or lightweight structures; waterproof membranes (such as SBS modified bitumen membranes) combined with insulation layers can address both waterproofing and heat insulation needs. Although these solutions require higher initial investments, they offer lower maintenance costs and greater safety over the long term.