How to Detect if a House is Prefabricated Panel Structure

To determine whether a house is constructed with prefabricated panels, a comprehensive assessment can be made using the following methods:

1. Preliminary Assessment Based on Construction Year

Prefabricated panel structures were predominantly used in early buildings. Houses constructed 15 years ago (especially before 1998) are highly likely to have been built with prefabricated panels, whereas those built after 15 years are more likely to feature cast-in-place structures. This trend is based on the evolution of construction technology in China: after 1998, cast-in-place techniques gradually became mainstream due to their superior earthquake resistance and structural integrity, although exceptions may exist in renovated older neighborhoods or specially designed buildings.

2. Observation of Pipeline or Conduit Layout Characteristics

• Prefabricated Panel Structures: The floor slabs typically have pre-installed columns or holes for pipeline installation, with the top conduits directly exposed on the surface, forming regularly arranged pipeline traces.
• Cast-in-Place Structures: Pipelines and conduits are fully embedded within the concrete, resulting in a smooth surface without exposed traces. If regularly distributed holes or conduit slots are observed on the floor slab surface, the possibility of prefabricated panels should be considered.

3. Analysis of Internal House Structure

• Relationship Between Walls and Beams/Columns:
  • Prefabricated Panel Houses: There are no beams above the walls, and no columns support the intersections between walls, with the floor slab directly resting on the walls.
  • Cast-in-Place Structures: There are visible horizontal beams above the walls and concrete columns at the corners, forming a frame structure.
• Joint Characteristics: The floor slabs of prefabricated panel houses exhibit horizontally and vertically intersecting beams at the corners or roof joints, which are typical traces of prefabricated panel assembly.

4. Inspection of Floor Slab Appearance and Touch Sensation

• Appearance: Prefabricated panels are regular in shape with noticeable gaps between panels (typically 2-3 cm wide), which may be patched with cement or filler; cast-in-place slabs have a smooth surface without assembly traces.
• Touch Sensation: When touching the edge of the floor slab, prefabricated panels may exhibit unevenness or roughness due to assembly, whereas cast-in-place slabs feel smooth and continuous.

5. Tapping the Floor Slab to Listen for Sounds

Tap the floor slab with a hard object (such as a key):

• Prefabricated Panels: Produce a clear, resonant sound with a long echo, similar to tapping a hollow wooden board.
• Cast-in-Place Slabs: Produce a dull, short sound, similar to tapping solid concrete. Note: This method should be combined with other evidence, as the thickness of the floor slab or finishing materials may affect the judgment.

6. Drilling Detection (Requires Professional Operation)

• Method: Drill a hole 3-5 cm deep in a concealed location on the floor slab (such as the top of a wardrobe):
  • If the drill frequently encounters voids (the reserved holes in prefabricated panels are approximately 8 cm in diameter) or discovers gaps between panels after drilling, it indicates a prefabricated panel structure.
  • If the drilling depth reaches 4 cm and still encounters solid concrete, it indicates a cast-in-place structure.
• Risk: Drilling may damage the floor slab structure. It is recommended that this be performed by professionals or that non-destructive testing methods be prioritized.

7. Review of Original Architectural Drawings

If the house retains its original architectural drawings, the floor slab structure can be directly checked for annotations:

• Drawings annotated with “prefabricated hollow panels” or “PC panels” indicate a prefabricated structure.
• Drawings annotated with “cast-in-place slabs” or “RC panels” indicate a cast-in-place structure. This method is the most accurate, but it is necessary to confirm that the drawings match the actual building.

Summary: It is recommended to conduct a preliminary assessment based on the construction year, pipeline characteristics, and internal structure, followed by verification through tapping, drilling, or drawing review. If uncertainty remains, a professional institution can be commissioned to conduct a structural inspection to avoid misjudgments that may affect the house safety assessment.