How Do Prefabricated Slab Houses Bear Loads

The load-bearing capacity of prefabricated slab houses is influenced by multiple factors such as national standards, materials, and structure, and requires comprehensive evaluation for reasonable use.

I. Load-Bearing Standards
National standards stipulate that residential floor slabs must withstand a live load of 200 kilograms per square meter, with a total load-bearing capacity of approximately 760 kilograms per square meter including the self-weight of the slab. There are three specific grades:

• Grade I slabs: With a load-bearing capacity of 100 kilograms per square meter, they are mostly used in temporary buildings or scenarios with low load requirements;
• Grade II slabs: With a load-bearing capacity of 200 kilograms per square meter, they are the common standard for ordinary residences;
• Grade IV slabs: With a load-bearing capacity of 400 kilograms per square meter, they are commonly found in old factory buildings or special industrial structures.
  The load-bearing capacities of different types of prefabricated slabs vary significantly:
• Concrete hollow prefabricated slabs: The national standard is 200-250 kilograms per square meter (uniformly distributed load);
• Solid prefabricated slabs: With a load-bearing capacity of 250-300 kilograms per square meter, solid slabs produced by large factories (with C30 or higher concrete and sufficient reinforcement) can reach 300 kilograms per square meter;
• Prestressed prefabricated slabs: With a span of less than 3 meters, they can bear 300-400 kilograms per square meter; with a span of more than 4 meters, the capacity drops to 250-300 kilograms per square meter.

II. Key Influencing Factors

1. Thickness: A 10-centimeter-thick prefabricated slab can bear 150-250 kilograms per square meter, while a 12-centimeter-thick one can reach 250 kilograms per square meter.
2. Materials: Higher concrete grades result in stronger load-bearing capacity; solid slabs are superior to hollow slabs; prestressed slabs, with the addition of high-strength steel wires, have better crack resistance and load-bearing performance.
3. Span: The larger the span, the lower the load-bearing capacity. For example, a hollow slab with a 2.4-meter span can bear 250 kilograms per square meter, while a 3.6-meter span drops to 200 kilograms per square meter, and spans over 4.2 meters may only bear 150-180 kilograms per square meter.
4. Construction: Insecure installation of supports can reduce load-bearing capacity by 30%; improper joint treatment or excessive thickness of the cement layer can weaken the floor slab's strength; adding beam supports can significantly enhance load-bearing capacity.
5. Load Type: Prefabricated slabs are sensitive to 'concentrated loads'. For example, the 200 kilograms per square meter load-bearing standard applies to uniformly distributed loads. Placing a 300-kilogram safe within a 1-square-meter area may crack the floor slab.

III. Usage Precautions

• When a single item weighs more than 200 kilograms, a pad should be added to disperse the pressure;
• Loads exceeding 400 kilograms per square meter may cause cracks, and a concentrated load of 20 tons (such as heavy equipment) can directly cause floor slab collapse;
• Detection methods include consulting architectural drawings or commissioning a professional agency to test with a pressure gauge.