Hidden Dangers of Prefabricated Panel Houses

Prefabricated panel houses have various hidden dangers in terms of structural integrity, core components, use and renovation, and other aspects, as detailed below:

Structural Integrity Hidden Dangers

• Foundation Issues: There are obvious settlement marks on the ground around the house, with height differences between indoor and outdoor floors. Oblique cracks appear at the bottom of the walls due to uneven foundation settlement.
• House Tilt: When viewed from a certain distance, the entire house shows visible tilt, skewing, or twisting phenomena.
• Poor Overall Seismic Resistance: Prefabricated panels are assembled by splicing, lacking the toughness of cast-in-place reinforced concrete. They often adopt a hollow design, with a much lower steel bar density compared to cast-in-place structures, resulting in poor overall integrity. They have poor seismic resistance during earthquakes or strong winds and may collapse or develop serious cracks. Micro-earthquakes or "frequent" minor tremors can cause structural fatigue, gradually expanding micro-cracks and making the structure extremely fragile.

Core Component Hidden Dangers

• Prefabricated Floor Slabs: Horizontal through-cracks appear on the ceiling (bottom of the prefabricated panels), or obvious cracks occur at the joints between panels. There are noticeable signs of downward bending or sinking in the middle of the floor slabs. At the positions where the ends of the prefabricated panels rest on the walls, the concrete is loose, crumbling, and the steel bars are exposed and rusted.
• Load-Bearing Walls: Vertical or oblique cracks appear on the load-bearing walls, or cracks and downward deformation occur at the lintels above door and window openings. The bricks or masonry at the bottom of the ground-floor walls show severe weathering, spalling, and loosening. For brick-concrete prefabricated panel houses of three stories or more, if there are no ring beams and constructional columns, the overall seismic resistance and safety will be significantly compromised.
• Node Connections: The support of the prefabricated panels on the walls is not firm, showing signs of looseness. According to regulations, the support length of the prefabricated panels on brick walls should not be less than 80mm. There are separations or cracks at the corners and junctions of the walls.

Use and Renovation Hidden Dangers

Unauthorized renovation behaviors are common, such as removing load-bearing walls without permission, opening door and window openings in load-bearing walls, and enlarging the opening sizes. Unauthorized additions of floors on the roof, installation of mezzanines, or stacking of excessively heavy items on the floor slabs. Houses originally designed as residences are converted into densely populated business premises, significantly increasing the live load and极易 (it should be "极易引发" which means "easily causing") causing safety accidents.

Other Hidden Dangers

Frequent cracks and water leakage weaken the overall strength of the walls and increase the risk of collapse. Moreover, the damp environment is prone to breeding mold and bacteria. Poor thermal insulation affects living comfort, increases energy consumption and health risks, and the sound insulation effect is poor. The service life is limited, generally only 30 to 40 years. The connection points are fragile, and over time, the connections weather and the steel bars rust, reducing strength. There may be issues with the material itself, such as thin steel bars and substandard concrete grades, resulting in high brittleness and easy fracture.