Calculation of Prefabricated Hollow Slabs for Houses
The calculation of prefabricated hollow slabs for houses mainly includes four aspects: weight, engineering quantity, building area, and price, as detailed below:
Weight Calculation: Taking a hollow prefabricated slab that is 10 cm thick and 0.5 meters wide as an example, the weight per meter depends on the material density and internal void ratio. First, calculate the total volume (1 meter × 0.5 meters × 0.1 meters = 0.05 cubic meters). Assuming the hollow part accounts for 25% of the total volume, the volume of the solid part is 0.05 cubic meters × (1 - 25%) = 0.0375 cubic meters. The weight of an ordinary concrete prefabricated slab (with a density of approximately 2400 kg/m³) is 0.0375 m³ × 2400 kg/m³ = 90 kilograms; the weight of a lightweight aggregate concrete prefabricated slab (with a density of approximately 1800 kg/m³) is 0.0375 m³ × 1800 kg/m³ = 67.5 kilograms. The actual weight should be confirmed based on the product specifications provided by the manufacturer, as different manufacturers' void ratio designs and material ratios will directly affect the final weight.
Engineering Quantity Calculation Rules: According to the 'Civil Engineering Textbook' and the 'Calculation Code for Engineering Quantities of Building Construction and Decoration', the calculation rules for the engineering quantity of prefabricated concrete hollow slabs are as follows: the volume occupied by individual holes within 300mm × 300mm is not deducted; when calculating the engineering quantity of prefabricated concrete stairs, the volume of hollow tread plates should be deducted. These rules ensure the accuracy and standardization of engineering quantity calculations.
Building Area Calculation: For single-story buildings, the building area is calculated as the sum of the horizontal projected areas of each floor above the exterior wall plinth, with full area calculated for floor heights of 2.20 meters or more and half area for less than 2.20 meters; for multi-story buildings, the first floor is calculated based on the horizontal perimeter area of the structure above the exterior wall plinth, and the second floor and above are calculated based on the horizontal perimeter area of the exterior wall structure, with the same floor height requirements as for single-story buildings; balconies are calculated as half of the horizontal projected area; for spaces under pitched roofs, full area is calculated if the net height exceeds 2.10 meters, half area if between 1.20 meters and 2.10 meters, and no area if less than 1.20 meters. When calculating, ensure accurate measurements and comply with local regulations regarding the building area of rural self-built houses.
Price Calculation: Typically, the price per square meter of prefabricated slabs is converted into a price per cubic meter by dividing the price per square meter by the thickness of the prefabricated slab to obtain the price per cubic meter. This method facilitates the comparison of price differences among prefabricated slabs of different thicknesses and provides a reference for engineering budgets.
