Load-Bearing Capacity of Old Houses with Prefabricated Panels

The load-bearing capacity of old houses with prefabricated panels needs to be comprehensively evaluated based on the construction era, the grade of the prefabricated panels, and the safety factor, with the actual load-bearing range typically falling between 180 kg and 560 kg per square meter.

I. Construction Era and Basic Design Values

Residential buildings constructed in the 1970s and 1980s typically have a live load design value of 150 kg per square meter. This value serves as a fundamental parameter in structural design, but the actual load-bearing capacity must consider the safety factor. According to regulations, the safety factor ranges from 1.2 to 1.4, so the actual load-bearing capacity is the design value multiplied by the factor, i.e., 180 kg/m² (150×1.2) to 210 kg/m² (150×1.4). This range is suitable for ordinary residential scenarios, such as placing furniture and daily walking.

For old houses built in the 1990s, the floor design load-bearing capacity may still be 150 kg per square meter, but industrial plants have higher design standards, reaching up to 360 kg per square meter. Similarly, when multiplied by the safety factor, the actual load-bearing range for industrial plants is 432 kg/m² (360×1.2) to 504 kg/m² (360×1.4).

II. Grade of Prefabricated Panels and Load-Bearing Differences

The load-bearing capacity of prefabricated panels is directly related to their grade:

• Grade I Panels: The standard value is 100 kg per square meter, suitable for storing lightweight items or daily use scenarios, such as bedrooms and living rooms in ordinary residences.
• Grade IV Panels: The standard value exceeds 400 kg per square meter, typically used in gyms, factories, and other places that need to bear heavy loads.

If composite panel technology (a method of enhancing structural performance by stacking concrete layers) is adopted, the load-bearing capacity can be increased by 30%. For example, a single 3.6-meter-long composite panel can have an ultimate load-bearing capacity of up to 2.2 tons. After conversion by area, its unit area load-bearing capacity is significantly higher than that of ordinary prefabricated panels, but such technology is mostly used for special engineering needs.

III. The Key Role of the Safety Factor

The safety factor is an important parameter in structural design, used to compensate for material performance fluctuations, construction errors, and losses during long-term use. For example, multiplying the 150 kg/m² design value of residences built in the 1970s and 1980s by 1.2 to 1.4 expands the actual load-bearing range, ensuring the structure remains safe during long-term use. If the house shows signs of aging, cracks, or renovation, the safety factor value should be reduced, or the load-bearing capacity should be reassessed through professional testing.