How to Identify Prefabricated Panel Houses
Identifying prefabricated panel houses can be done through the following methods:
1. Observe the floor slab structure
Prefabricated panels typically exhibit a regular block shape, with noticeable gaps between panels. The surface may have slight irregularities or seam marks. In contrast, cast-in-place slabs are formed as a whole, with a smooth and flat surface, no obvious seams, and a natural transition at the junction between the slab and the wall. By directly observing the appearance of the floor slab, you can make a preliminary determination of the structural type.
2. Check the construction year
Prefabricated panel structures were commonly used in early buildings, especially those constructed before 1998. Due to the limitations of construction techniques and materials at that time, prefabricated panels were widely adopted for their low cost and fast construction speed. In recent years, newly built houses generally use cast-in-place concrete structures. Houses built more than 15 years ago (around before 2008) are mostly prefabricated panel houses, while those built after 15 years are mainly cast-in-place slab houses. However, it should be noted that there may be exceptions in some old residential area renovations or special designs.
3. Tap the floor slab to listen to the sound
Tap the floor slab lightly with a hard object (such as a key or a small hammer). If the sound is clear and has a long echo, it may be a prefabricated panel (due to internal voids or gaps between panels causing sound wave reflection). If the sound is muffled and short, similar to the feeling of "drumming", it may be a cast-in-place slab (due to its overall density and faster sound wave absorption). However, this method should be combined with other methods for a comprehensive judgment to avoid misjudgment.
4. Examine the house design drawings
If you can obtain the original design drawings of the house, you can directly check the annotations on the floor slab structure. If the drawings clearly indicate "prefabricated hollow panels" or "assembled floor slabs", it is a prefabricated panel structure. If they indicate "cast-in-place reinforced concrete floor slabs", it is a cast-in-place structure. This method is the most accurate, but it requires the drawings to be authentic and reliable.
5. Observe the areas where pipes are laid
To facilitate pipe laying, prefabricated panels usually have pre-reserved holes or column supports inside the panels. Therefore, regular holes or columns can be seen at the points where pipes pass through the floor slab. Cast-in-place slabs have no pre-reserved structures, and pipes need to be chiseled out later, with irregular edges at the penetration points. This method is suitable for areas with concentrated pipes, such as bathrooms and kitchens.
6. Analyze the internal walls of the house
Due to span limitations, prefabricated panel houses often have internal walls without beams, and there are no columns at the intersections of walls. The load of the floor slab is directly transferred to the walls. In cast-in-place slab houses, due to overall stress, there are usually beams above the walls, and columns at the intersections of walls for support. By observing whether there are beam and column structures at the junction between the ceiling and the walls, you can assist in the judgment.
7. Drill holes in the floor slab for verification
During the manufacturing of prefabricated panels, holes with a diameter of 8 centimeters are pre-reserved every about 3 centimeters (used to reduce weight or for threading). Use an impact drill to make three holes at intervals of 5 centimeters on the floor slab. If you encounter voids when drilling, it is a prefabricated panel. If it is solid throughout, it is a cast-in-place slab. This method is destructive and should be used with caution. It is recommended to prioritize non-destructive testing methods.
