How to Calculate the Weight of Prefabricated Houses

The calculation of the weight of prefabricated houses requires consideration of specific component types, material parameters, and structural design. Common methods and key parameters are as follows:

I. Core Calculation Methods

1. Weight Calculation of Prefabricated Panels
   The weight formula for solid prefabricated panels is: Weight (kg) = Length (m) × Width (m) × Thickness (m) × Density (kg/m³).

   • The density of concrete typically ranges from 2400 to 2500 kg/m³, with lightweight concrete as low as 1600 kg/m³ and reinforced concrete potentially reaching 2600 kg/m³.
   • Example: A solid prefabricated panel measuring 3 m in length, 0.5 m in width, and 0.12 m in thickness weighs approximately 3 × 0.5 × 0.12 × 2400 = 432 kg.
   • Hollow prefabricated panels should be calculated based on the net cross-section, weighing 30% to 50% less than solid panels.

2. Self-Weight Calculation of Floor Slabs
   The self-weight of a floor slab is calculated as the unit weight multiplied by the thickness, with additional weights for surface layers and plastering:

   • A 100 mm thick reinforced concrete floor slab (unit weight of 25 kN/m³) has a self-weight of 250 kg/m².
   • If a 5 cm mortar surface layer (unit weight of 20 kN/m³) and a 2 cm plastering layer are added, the total self-weight becomes 3.9 kN/m² (approximately 390 kg/m²).

3. Overall Estimation (Two-Story House)
   The weight of a two-story prefabricated panel house is approximately 750 kg/m², depending on factors such as floor area, thickness, concrete density, and steel reinforcement quantity. For example, when the concrete density is 2400 kg/m³, an increase in steel reinforcement significantly increases the weight.

II. Key Influencing Factors

1. Material Density

   • The density of concrete ranges from 1600 to 2600 kg/m³, requiring adjustments based on material type (e.g., lightweight concrete, reinforced concrete).
   • Steel reinforcement content: Each 1% increase in reinforcement ratio increases the weight by approximately 20 kg/m³.

2. Structural Design

   • Hollow structures or sandwich insulation designs can reduce weight, with hollow prefabricated panels weighing 30% to 50% less than solid panels.
   • Irregular components should be decomposed into regular geometric shapes for segmented calculation to avoid errors.

3. Safety Margin and Error Control

   • A 10% safety margin should be reserved during calculations to account for uncertainties such as moisture content variations.
   • Industry standards (JGJ 1-2014) require the weight error of prefabricated components to be controlled within ±5%.

III. Precautions

• Design parameters (e.g., component dimensions, material types, reinforcement ratios) must be clarified before calculation, with irregular components requiring decomposition.
• The final results should be verified in conjunction with professional drawings or by consulting construction professionals to avoid relying solely on theoretical estimates.
• Special designs (e.g., earthquake-resistant structures, large-span floor slabs) require additional consideration of dynamic loads and structural stability.