Images of Cracks in Prefabricated Panel Houses

Prefabricated panel houses typically exhibit the following types of cracks. Although images cannot be provided directly, descriptions can help understand their characteristics:

First Type: Unidirectional Parallel Cracks
These cracks often appear in the floor areas of older prefabricated panel houses, extending unidirectionally and parallel to one side of the house's wall. They form due to the asynchronous deformation of two adjacent prefabricated panels over long-term use, caused by material aging, temperature changes, or load differences. For example, when there is a significant temperature difference between indoors and outdoors in winter, varying degrees of shrinkage in the prefabricated panels can trigger such cracks. If the floor does not exhibit significant deflection (i.e., sagging or deformation downward), it generally indicates that the overall structural load-bearing capacity has not been significantly affected, with lower safety risks. However, these cracks can serve as channels for rainwater penetration, leading to water leakage on indoor ceilings.

Second Type: Vertical Cracks on the Side of Panel Ends
These cracks are commonly found on the side surfaces at the ends of prefabricated panels, extending vertically downward from the top to the bottom of the panel, and are generally narrow in width. Their causes are closely related to construction defects:

1. Panel Warping: During production or transportation, uneven stress can cause slight bending in the prefabricated panels. After installation, gaps may exist between the panel ends and the walls or beams, leading to stress concentration and crack formation.
2. Uneven Support Padding: If a level is not used to adjust the support padding (such as wooden wedges or mortar layers) beneath the prefabricated panels during construction, excessive local stress on the panel ends can result in cracks.
   These cracks are usually confined to the panel end areas, with limited impact on the overall structural safety. However, timely repairs are necessary to prevent crack enlargement or steel reinforcement corrosion.

Recommendations for Crack Treatment

1. For unidirectional parallel cracks, if the width is less than 0.3 millimeters and there is no leakage, no treatment may be necessary temporarily. If the width exceeds 0.3 millimeters or leakage is present, pressure grouting with materials such as epoxy resin should be used for repair, along with enhanced waterproofing measures.
2. For vertical cracks on the side of panel ends, loose material inside the cracks should be removed first, followed by filling with cement mortar or elastic sealant. Additionally, reinforcing steel mesh or carbon fiber sheets should be added at the panel ends to enhance local crack resistance.
3. Regardless of the type of crack, regular observation of their development is necessary after repair. If the crack width continues to increase or new cracks appear, a professional organization should be commissioned to conduct a structural safety assessment.