Bearing Capacity of Prefabricated Slab Floors in Houses

The bearing capacity of prefabricated slab floors in houses is influenced by multiple factors and is not a fixed value. National standards stipulate that residential floors must be able to withstand at least 200 kilograms of live load, with the actual total bearing capacity (including the self-weight of the floor) being approximately 760 kilograms.

Bearing Capacity of Different Types of Prefabricated Slabs

• Concrete Hollow Prefabricated Slabs: Calculated based on uniformly distributed load, the national standard is 200 - 250 kilograms per square meter. For example, a hollow slab that is 3.6 meters long and 0.6 meters wide has an area of 2.16 square meters and a total bearing capacity of about 432 kilograms. It can evenly accommodate about 8 bags of 50-kilogram cement; however, concentrated stacking may crack the floor.
• Solid Prefabricated Slabs: More robust than hollow slabs, they are commonly used in areas with heavier loads such as kitchens and bathrooms, with a bearing capacity of 250 - 300 kilograms per square meter. Solid slabs produced by large factories (with sufficient reinforcement and a concrete grade of C30 or higher) can have a bearing capacity of up to 300 kilograms per square meter.
• Prestressed Prefabricated Slabs: Commonly used in new buildings, they generate prestress through high-strength steel wire tensioning, enhancing crack resistance and bearing capacity. For spans within 3 meters, they can withstand 300 - 400 kilograms per square meter; for spans over 4 meters, the bearing capacity remains at 250 - 300 kilograms per square meter, which is 20% higher than that of ordinary prefabricated slabs of the same span.

Key Factors Affecting Bearing Capacity

• Span: The shorter the prefabricated slab, the stronger its bearing capacity. For example, a hollow slab with a span of 2.4 meters can withstand 250 kilograms per square meter, while a 3.6-meter span drops to 200 kilograms, and spans over 4.2 meters may only withstand 150 - 180 kilograms.
• Thickness and Reinforcement: A 10-centimeter-thick prefabricated slab has stronger bearing capacity than an 8-centimeter-thick one; the thicker and denser the steel bars (e.g., 8-millimeter steel bars spaced 15 centimeters apart), the higher the bearing capacity.
• Load Type: Prefabricated slabs are sensitive to concentrated loads. Evenly spreading 200 kilograms of sand is harmless, but placing 300 kilograms of heavy objects (such as a safe) within 1 square meter may crack the floor.
• Other Factors: A higher concrete grade enhances bearing capacity; when the span exceeds 4 meters or the supports are not firmly fixed, the bearing capacity is reduced by 30%; construction quality (such as joint treatment and cement thickness) also significantly affects floor strength. Additionally, the live load grade (e.g., Grade IV slabs in the southwest region can withstand 400 kilograms, while Grade II slabs in ordinary residences can only withstand 200 kilograms) is also an important consideration.