Prefabricated House Safety Inspection

The safety inspection of prefabricated houses should focus on three core dimensions: structural integrity, the condition of components themselves, and usage and modification situations. The specific inspection points are as follows:

I. Structural Integrity and Foundation Inspection

1. Foundation: Check for obvious signs of settlement around the house, such as ground cracking, sinking, or differences in height between indoor and outdoor floors. Observe whether there are diagonal cracks at the bottom of the walls caused by uneven foundation settlement. These cracks usually extend from the corners to the middle of the walls, and their widths may increase over time.
2. House Tilt: Stand 10-15 meters away from the house and visually inspect whether the entire house shows any visible tilt, warping, or twisting, or use a level for assistance. Tilt may be caused by foundation softening, uneven soil quality, or construction defects and requires special attention.

II. Special Inspection of Core Components

1. Prefabricated Floor Slabs:
   • Bottom Cracks: Look up at the ceiling (bottom of the prefabricated slabs) and focus on checking for horizontal through-cracks or cracks at the joints between slabs. These cracks may be caused by uneven stress on the floor slabs or concrete aging.
   • Deflection and Deformation: Check whether there is obvious downward bending or sinking in the middle of the floor slabs. If the deformation exceeds the allowable value specified in the regulations (e.g., L/250, where L is the span of the floor slab), immediate action is required.
   • End Damage: Examine the positions where the prefabricated slabs rest on the walls at both ends. Confirm whether the concrete is loose, crumbling, or whether the steel bars are exposed and rusted. These issues can weaken the load-bearing capacity of the floor slabs.
2. Load-Bearing Walls:
   • Stress Cracks: Focus on checking for vertical or diagonal cracks in the load-bearing walls, or cracks and downward deformation above the lintels of doors and windows. These cracks may be caused by excessive stress on the walls or foundation settlement.
   • Wall Weathering: Check whether the bricks or masonry at the bottom of the walls show severe weathering, peeling, or looseness, especially in houses in humid environments.
   • Structural Measures: Confirm whether the house is equipped with ring beams and constructional columns (mandatory for brick-concrete prefabricated houses of 3 stories or more). Their absence will significantly reduce the overall seismic resistance and safety.
3. Node Connections:
   • Lap Length: Check whether the support length of the prefabricated slabs on the brick walls complies with the regulations (should not be less than 80mm). Insufficient support can easily lead to loosening or detachment of the floor slabs.
   • Tie Conditions: Check whether the corners and junctions of the walls are separated or have cracks. Insufficient tie conditions will affect the structural integrity.

III. Inspection of Unauthorized Modifications and Usage Environment

1. Removal or Modification of Load-Bearing Walls: Verify whether the house has had load-bearing walls removed without authorization, doors or windows opened in load-bearing walls, or the sizes of openings enlarged. Such actions will directly damage the structural stress system.
2. Unauthorized Additions (Increased Load): Check whether additional floors have been built on the roof, mezzanines added, or heavy equipment (such as water tanks or machine tools) stacked on the floor slabs without authorization. Overloading may cause the floor slabs to break or the walls to crack.
3. Change of Use: If a house originally designed as a residence has been converted into a place with a large number of people (such as a restaurant or KTV), it is necessary to evaluate the impact of the increased live load on the structure and carry out reinforcement if necessary.

Daily Monitoring and Professional Appraisal: Ordinary families can spend 10 minutes each month observing sensitive areas such as wall-beam column connections and around door and window openings. If cracks are found, mark them with a pencil and record the date, and regularly observe whether they expand. Preliminary inspections cannot replace professional appraisals. If safety hazards are found, a qualified unit should be commissioned to conduct an appraisal, and the house should be dealt with according to the results.