Is the Roof of Community Houses Made of Prefabricated Panels?

To determine whether the roof of community houses is made of prefabricated panels, a comprehensive analysis can be conducted using the following methods:

1. Preliminary Judgment Based on Construction Year

Houses built before 1998 are more likely to use prefabricated panels, as prefabricated floor slabs were commonly used in the construction industry at that time. In 2002, the state explicitly prohibited the use of prefabricated panels in newly built commercial housing, and houses built after 2003 generally use cast-in-place floor slabs. If the house was built before 1998, it requires focused investigation; if it was built after 2003, it is most likely a cast-in-place structure.

2. Observation of the Structure at Pipe Installation Points

Prefabricated panels require columns or reserved holes to support pipes. If there are obvious columns or regular holes where pipes pass through the floor slab in the house, it may be a prefabricated panel. Cast-in-place floor slabs, being poured as a whole, allow pipes to be directly embedded in the concrete without additional support structures.

3. Inspection of the Distribution of Beams and Columns Inside the House

• Characteristics of Prefabricated Panels: There are no horizontal beams above the walls, no columns at the intersections of walls, and the walls are load-bearing (non-removable).
• Characteristics of Cast-in-Place Panels: In frame structures, the width of beams and columns is greater than the thickness of the walls. In brick-concrete structures using cast-in-place panels, there may be horizontal beams above the walls, and columns at the intersections of walls for support. If obvious beams and columns are visible between walls, it is a cast-in-place structure.

4. Drilling Verification Method (Proceed with Caution)

Prefabricated panels have holes with a diameter of 8 centimeters every 3 centimeters inside. An impact drill can be used to drill three holes 5 centimeters apart on the floor slab:

• If holes are drilled into, it is a prefabricated panel;
• If there are no holes and the concrete is continuous, it is a cast-in-place panel. Note: Drilling may damage the floor slab structure. It is necessary to obtain the consent of the property management and have it carried out by professionals.

5. Observation of Cracks and Knocking Sounds

• Crack Characteristics: Prefabricated panels are prone to parallel and regular cracks; cast-in-place panels have randomly shaped and irregularly distributed cracks.
• Sound Identification: Knocking on a prefabricated panel produces a dull sound due to the internal holes, while a cast-in-place panel produces a clear sound due to its overall strength. When jumping, the vibration of a prefabricated panel is transmitted along the panel, while the vibration of a cast-in-place panel spreads in all directions and is more pronounced.

6. Inspection of Ring Beam Settings

Prefabricated panel houses have poor earthquake resistance, and some areas add ring beams to improve overall stability. If each floor of the building has outward-protruding ring beams and their shape does not match the architectural style, it may be a sign of a prefabricated panel structure.

7. Inquiry into Building Archives

By consulting the building archives at the local archives or housing management department, key information such as the type of floor slab and the construction year can be directly obtained, providing the most accurate and reliable results.