How to Calculate the Prefabrication Rate of a House

The calculation of a house's prefabrication rate is determined based on the building type and local standards, with the core being to quantify the degree of assembly through the ratio of the volume of prefabricated components to the total volume of concrete. Here are the specific calculation methods and key points:

I. General Calculation Method (Reinforced Concrete Prefabricated Buildings)
The core formula for the prefabrication rate is:
Prefabrication Rate = (Volume of Prefabricated Concrete Parts / Total Volume of Concrete) × 100%

1. Volume of Prefabricated Concrete Parts: Refers to the total volume of concrete in prefabricated components within the main structure (such as beams, columns, and floor slabs) and the exterior enclosure structure (such as prefabricated exterior walls and balcony slabs).
2. Total Volume of Concrete: The sum of the volumes of concrete in the prefabricated parts and the cast-in-place parts (such as floor slabs and beams cast on-site).
   Example: If a building has a volume of prefabricated components of 800 m³ and a volume of cast-in-place concrete of 200 m³, the prefabrication rate is 800 / (800 + 200) × 100% = 80%.

II. Calculation Rules in Shanghai's Local Standards
Shanghai adopts a correction coefficient method, with the formula being:
Prefabrication Rate of a Single Building = (∑ (Volume of Prefabricated Components × Component Correction Coefficient) / Total Volume of Components) × 100%

1. Component Scope: Includes exterior enclosure walls (load-bearing/non-load-bearing), internal load-bearing walls, beams, columns, floor slabs, stairs, balconies, air conditioning panels, etc., excluding non-load-bearing internal partitions. If the parapet is prefabricated, it can be included in both the numerator and the denominator.
2. Correction Coefficient: Different component types correspond to different coefficients (for example, the correction coefficient for prefabricated exterior walls may be 1.1, and for floor slabs, it may be 1.0). These coefficients need to be determined by referring to local regulations and tables to reflect the technical difficulty or functional value of the components.
   Example: For a building with a prefabricated floor slab volume of 500 m³ (coefficient 1.0) and a prefabricated exterior wall volume of 300 m³ (coefficient 1.1), and a cast-in-place part volume of 200 m³, the prefabrication rate is (500 × 1.0 + 300 × 1.1) / (500 + 300 + 200) × 100% = 73%.

III. Key Considerations

1. Differences in Structural Forms: The calculation of the prefabrication rate for steel-structure, wood-structure, and other prefabricated buildings may involve the volume of steel or wood and should refer to special regulations.
2. Priority of Local Standards: In addition to Shanghai, Shenyang, Beijing, and other places may have independent calculation rules, which should be based on local documents.
3. Calculation Boundaries: Usually, only the main structure and enclosure structure above the outdoor ground level are counted, while basements and foundation parts are generally not included.

IV. Reference Basis
The calculation should comply with the "Technical Standard for Prefabricated Concrete Buildings" (GB/T 51231) and local standards (such as Shanghai's "Evaluation Standard for Prefabricated Buildings" DG/TJ 08-2068) to ensure compliance with regulations.