How to Inspect Prefabricated Houses

The inspection of prefabricated houses requires strict verification in stages and according to standards, focusing on delivery milestones, component accuracy, installation quality, problem identification, and document completeness. The specific steps are as follows:

I. Delivery Milestone Inspection

There are 10 key milestones for prefabricated houses that need to be included in the contract appendices as inspection references:

1. Plan Freeze: Confirm that the house type, appearance, and configuration list are consistent with the contract, and both parties sign to make it effective;
2. Factory Inspection: Check the appearance of components (no cracks or deformations), the smoothness of door and window opening and closing, and basic functions (such as socket power and drainage hole patency);
3. On-site Installation: Record the installation cycle, personnel allocation, and daily progress to avoid project delays;
4. Water and Electricity Commissioning: Test the lighting and socket power supply, whether the drainage slope meets standards, and whether equipment (such as air conditioners and water heaters) operates normally;
5. Waterproofing and Sealing: Focus on inspecting the waterproof layer of the bathroom floor/wall, the sealing strips of doors and windows, and the waterproof membrane of the roof to ensure no leakage;
6. Delivery Inspection: Clarify inspection standards (such as surface flatness ≤ 3mm/2m), problem rectification deadlines (such as repair within 7 days), and warranty periods (usually 1-2 years).

II. Core Inspection Standards

1. Prefabricated Component Accuracy:
   • Geometric Dimensions: The length/width/thickness deviation of wall panels and floor slabs should be ≤ ±3mm, and the diagonal deviation should be ≤ 5mm;
   • Embedded Part Positions: The positioning deviation of sleeves and steel bars should be ≤ ±2mm to avoid installation difficulties later;
   • Surface Flatness: The deviation should be < 3mm/2m, and a 2-meter straightedge should be used to check walls and floors.
2. On-site Installation Quality:
   • Perpendicularity: The perpendicularity deviation of components should be < H/1000 (H is the height) and ≤ 10mm, measured with a laser plumb bob;
   • Grouting Fullness: The fullness of sleeve grouting material should be ≥ 95%, with a pressure of 0.2-0.4MPa, detected through observation holes or ultrasonic testing;
   • Levelness: The cumulative deviation of each floor slab should be ≤ 10mm, measured with a level gauge.

III. Common Problem Identification

1. Bathroom: Check the integrity of the waterproof layer (no leakage in a 48-hour closed-water test), whether the drainage slope is ≥ 2%, and the sealing of the connection between the floor drain and the drainage pipe;
2. Door and Window Sealing: After closing doors and windows, use a tissue to test for air leakage at the gaps and check for water leakage on rainy days;
3. Concealed Works: Verify the wear condition of pre-embedded lifting rings, the rust treatment of exposed steel bars (such as painting with anti-rust paint), and whether the positions of pre-embedded pipelines are consistent with the design.

IV. Inspection Document Verification

1. Construction Documents: Include construction logs, records of concealed works (such as steel bar binding and waterproof layer construction), and material certificates (such as concrete strength reports and door and window sealant test reports);
2. As-built Drawings: Should be consistent with the actual on-site construction and include design change documents (such as wall modifications and pipeline adjustments);
3. Special Inspection Documents: Fire protection inspection certificates, planning inspection certificates, and environmental protection test reports (such as formaldehyde emission compliance).

V. Precautions

1. If you have no inspection experience, you can request the manufacturer to clarify the 'delivery scope' (such as whether it includes interior decoration and furniture) to avoid additional charges for temporary additions;
2. Refer to the national standard 'Technical Standard for Prefabricated Concrete Buildings' (GB/T 51231-2016) and industry specifications to ensure inspection compliance.