Identification Criteria for Prefabricated Slab Houses

The identification criteria for prefabricated slab houses can be comprehensively judged through the following methods:

1. Observe the structural characteristics of the floor slab
Prefabricated slabs are assembled from prefabricated concrete components, presenting a regular block-like structure on the surface. There are obvious gaps between the slabs, and there may be misalignments or height differences at the joints. In contrast, cast-in-place slabs are formed as a whole by pouring concrete on-site, with a smooth and flat surface, no joint marks, and tightly integrated edges with the walls. If regular rectangular blocks or gaps are visible on the floor slab, it can be preliminarily identified as a prefabricated slab structure.

2. Verify the construction year of the house
According to the evolution of building codes, the use of prefabricated slabs has been completely banned in newly built commercial housing since 2003. Therefore, houses built within the last 15 years (after 2008) basically adopt cast-in-place structures. If the house was built before 2000, especially multi-story residential buildings from the 1980s to 1990s, the probability of using prefabricated slabs is significantly higher. However, it should be noted that some old residential areas may have reinforced or replaced the floor slabs during renovations.

3. Tap the floor slab to distinguish its quality by sound
Use a hard object (such as a metal key) to gently tap the floor slab:

• Prefabricated slabs, due to internal cavities or joint gaps, produce a clear sound with a long echo, similar to tapping a hollow wall;
• Cast-in-place slabs, being solid concrete structures, produce a dull and short sound, similar to the feedback from tapping a thick wall.
  This method should be combined with other characteristics for comprehensive verification to avoid the influence of floor slab thickness or decoration layers on the judgment.

4. Check the original design drawings of the house
If the original design drawings can be obtained, the floor slab structure description can be directly viewed. Drawings labeled as "prefabricated hollow slabs" or "prestressed hollow slabs" indicate prefabricated structures, while those labeled as "cast-in-place reinforced concrete floor slabs" indicate cast-in-place structures. This method is the most accurate, but it is difficult for ordinary homeowners to obtain complete drawings.

5. Observe the pipeline layout and wall structure

• Pipeline layout: Prefabricated slabs require reserved pipeline holes. If regular columnar supports are visible below the floor slab or reserved holes are present where pipelines pass through the slab, it may indicate a prefabricated structure; cast-in-place slabs, on the other hand, have pipelines laid through later slotting, with no regular holes.
• Wall structure: The walls of prefabricated slab houses usually bear the load directly, with no structural columns at the intersections of walls and no obvious beam structures above the walls; the walls of cast-in-place slab houses form an overall framework with beams and columns, and concrete columns or beams are visible at the corners of the walls.

6. Drilling detection method (requires professional operation)
During the production of prefabricated slabs, holes with a diameter of about 8 centimeters are reserved every 3-5 centimeters (for weight reduction or wiring). Use an impact drill to drill three holes at 5-centimeter intervals in a concealed location on the floor slab (such as the top of a wardrobe). If the drill bit enters a cavity or encounters a hole, it can be confirmed as a prefabricated slab. This method may damage the floor slab structure and should be used with caution, with non-destructive testing methods being preferred.