Quality Standards for Finished Products of Prefabricated Houses

The quality standards for finished products of prefabricated houses should be considered from the following aspects:

I. Compliance with National and Industry Standards As a construction engineering product, the quality of prefabricated houses must meet the requirements of the "Product Quality Law of the People's Republic of China", ensuring human health, personal and property safety, and the absence of unreasonable dangers that threaten safety. For example, the "Appearance Quality Requirements and Dimensional Deviation Limits for Prefabricated Concrete Components in Prefabricated Buildings (Draft for Comments)" issued by the Ministry of Housing and Urban-Rural Development specifies the allowable ranges for appearance defects (such as cracks, honeycombs, and pockmarks) and dimensional deviation limits (such as tolerances for length, width, and flatness parameters) of prefabricated concrete components, ensuring that they meet engineering safety requirements.

II. Possession of Required Performance Characteristics Prefabricated houses must meet core performance characteristics such as structural safety, living comfort, and the integrity of equipment and facilities. Structural safety includes indicators such as earthquake resistance, wind resistance, and load-bearing capacity, which require verification through professional design and testing; living comfort involves performance in terms of sound insulation, heat insulation, and ventilation, which must comply with building energy efficiency standards; equipment and facilities (such as water and electricity pipelines, doors and windows, and sanitary ware) must be installed in accordance with specifications and operate stably. If there are performance flaws (such as inadequate sound insulation), producers must inform users in advance.

III. Strict Quality Inspection System A multi-level inspection system must be established during the production process:

1. Raw Material Inspection: In accordance with the "Regulations on the Quality Management of Construction Projects", construction units must inspect materials such as steel bars, concrete, and molds to ensure they meet design and contractual requirements.
2. Process Inspection: After the completion of each process (such as steel bar binding and concrete pouring), self-inspection, mutual inspection, and special inspection are required. For example, the spacing and welding quality of steel bar cages must be checked during binding, and the slump and compaction density of concrete must be verified during pouring.
3. Finished Product Acceptance: After the overall completion of the prefabricated house, the entity quality must be verified through sampling inspections and measurements, such as checking the verticality of walls and the flatness of floor slabs, to ensure compliance with the requirements of the "Regulations on the Quality Supervision and Management of Housing Construction and Municipal Infrastructure Projects".

IV. Specific Component Manufacturing Specifications

1. Steel Bar Section: This covers raw material quality (such as tensile strength and yield strength), stacking identification (rust prevention, classified storage), cutting and bending accuracy (dimensional deviation ≤ ±5mm), binding process (uniform spacing, firmness), and acceptance procedures (such as concealed work acceptance).
2. Mold Installation: Technical disclosures must clarify the installation sequence, materials must meet strength requirements, construction equipment (such as laser leveling instruments) must be calibrated and qualified, and after installation, the verticality and flatness must be checked (deviation ≤ 2mm).
3. Concrete Pouring: Detailed standards exist from raw materials (cement, sand and gravel with a mud content ≤ 3%) to pouring processes (layered vibration, avoidance of segregation), to surface finishing (surface flatness ≤ 3mm) and curing (covering and moisturizing for ≥ 7 days).
4. Subsequent Processes such as Steam Curing and Demolding: Temperature control is required (such as a steam curing heating rate ≤ 15°C/h), and the demolding time must be controlled (concrete strength reaching more than 75% of the design value) to ensure that components are free from cracking and deformation.