Prefabricated Slab Roof of House
The prefabricated slab roof of a house is a roof form constructed primarily with prefabricated slabs. It was once widely used in rural self-built houses but has gradually been replaced due to numerous issues.
Structure and Characteristics of Prefabricated Slab Roofs
Prefabricated slabs are cement components manufactured in factories. They are made by nailing wooden models, arranging steel bars, and pouring cement. There are two types: solid and hollow. The hollow structure achieves lightweighting by reducing the non-load-bearing concrete, with a floor slab thickness of generally about 12 centimeters. In rural self-built houses, the use of prefabricated slabs as roofs was more common before 20 years ago, mainly because of their low cost and fast construction speed, with installation possible in just one day or half a day.
Disadvantages of Prefabricated Slab Roofs
- Waterproofing Issues: There is a high probability of rain leakage during waterproofing. Among rural houses with prefabricated slab roofs, 8 out of 10 experience rain leakage, and even the waterproofing industry cannot guarantee 100% leak-proofing. This is because there are splicing gaps between the prefabricated slabs, and if the waterproofing treatment is improper, rainwater can easily seep into the house through these gaps.
- Weak Earthquake Resistance: They cannot be used in earthquake-prone areas due to their low seismic coefficient, which can easily lead to collapse. The connections between the prefabricated slabs are not strong enough, and under earthquake action, they are prone to displacement and fracture, affecting the overall structural safety of the house.
- Poor Thermal Insulation: Although they have a hollow structure, their thermal insulation is poor. The indoor temperature is high in summer and low in winter. Generally, secondary roofing material coverage is required on the floor slab to compensate. This is because the material and structure of the prefabricated slabs determine their poor thermal conductivity, making it difficult to effectively block external temperature changes.
Current Situation of Prefabricated Slab Roofs
With the development of construction technology, cast-in-place concrete and prefabricated buildings are gradually replacing traditional prefabricated slab houses. Since 2022, China has implemented a policy of renovating old residential areas, focusing on repairing and renovating prefabricated slab houses and only demolishing buildings that meet the criteria for dangerous houses. Existing prefabricated slab houses generally have issues such as weak earthquake resistance, poor sound and thermal insulation, and a service life of about 30 - 50 years. Some regions have already started demolition work.
