Prefabricated Slab Roof of Prefab Houses

The prefabricated slab roof was a commonly used floor form in early 20th-century architecture, and it was widely applied in rural self-built houses about 20 years ago. However, it has drawbacks in terms of waterproofing, earthquake resistance, and thermal insulation.

Characteristics and Historical Applications

Prefabricated slabs are concrete prefabricated components produced and processed in prefabrication yards and then directly transported to construction sites for installation. In the field of rural self-built houses, the use of prefabricated cement slabs as roofs was relatively common before 20 years ago. This was mainly because their prices were relatively low, and the construction speed was extremely fast. The hoisting could be completed in a day or half a day, greatly shortening the house-building cycle and meeting the demand for rapid house construction in rural areas at that time.

Drawbacks

• Waterproofing Issues: There is a relatively high probability of rain leakage when waterproofing is done on the prefabricated slab roofs of houses. Among rural houses with prefabricated slabs as roofs, 8 out of 10 experience rain leakage. Even the waterproofing industry cannot guarantee 100% leak-proofness. This is because gaps are prone to form at the joints between prefabricated slabs, and rainwater can easily seep into the house through these gaps.
• Poor Earthquake Resistance: Prefabricated slabs should not be used for house construction in earthquake-prone areas. Due to their structural characteristics, the earthquake resistance coefficient of prefabricated slabs is too low. In the event of an earthquake, the slabs are prone to dislocation and separation between each other, which can lead to house collapse and pose a serious threat to life and property safety.
• Poor Thermal Insulation: The thickness of prefabricated slabs is generally about 12 centimeters. Although they have a hollow structure, their thermal insulation performance is not good. In summer, the temperature inside the house can be very high, like a "steamer"; in winter, the indoor temperature can be very low, and additional insulation measures are required. Generally, secondary roofing material coverage is needed on the floor slabs to make up for this drawback, such as adding an insulation layer.

Pricing

The prices of prefabricated slab roofs for houses vary depending on factors such as material and specifications. For example, for reinforced concrete hollow slab factory and civilian house floor and roof prefabricated slabs, some are priced at 24.0 yuan per meter, and some 12-centimeter floor slabs are priced at 18.0 yuan per meter.