Cracking in Prefabricated Panel Houses

Cracking in prefabricated panel houses requires high attention. Its causes are complex and its impacts are significant, necessitating comprehensive assessment and proper handling.

Causes of Cracking

• Low structural strength of the house: Prefabricated panel houses are assembled from prefabricated panels, inherently lacking in robustness and toughness. They often adopt a hollow design, with the quantity and distribution of steel bars being less scientific and reasonable compared to cast-in-place houses. Even slight vibrations can loosen the joints between floor panels. Over time, cracks will become more numerous and larger, spreading from wall seams to the floor panels.
• Service life factors: The service life of prefabricated panel houses is relatively short, typically ranging from 20 to 30 years. As the service years increase, issues such as wall cracks and ceiling water leakage will emerge. The originally sturdy structure becomes precarious, and many old prefabricated panel houses are identified as 'dangerous houses'.
• Wall cracks and susceptibility to water leakage: Prefabricated panel houses are prone to wall cracks and ceiling water leakage. On rainy days, it may rain heavily outside while lightly inside the house. After the rain stops, water may still drip inside, leading to mottled walls, increased cracks, deformed floors, leaking windows, and deteriorated sound insulation.

Manifestations of Cracking

In old houses with brick-concrete structures and prefabricated panel roofs, there may be through-cracks on the roof. After removing the roof base layer, large gaps between the prefabricated panels can be observed, with the maximum gap reaching up to 4 centimeters. Moreover, the prefabricated panels are uneven, with height differences between two panels. Through-cracks can also be seen on the cement floor.

Assessment of Cracks

The danger level of a house cannot be simply determined based on the width of cracks. According to the current 'Standard for Dangerous House Appraisal' JGJ 125 - 2016, professional appraisal requires a comprehensive consideration of factors such as the location, length, depth, direction, quantity, and development of cracks, as well as the load-bearing walls, beams, panels, columns, foundations, component connections, and overall deformation of the house. Houses are ultimately classified into four grades: A, B, C, and D. Grade C indicates that some load-bearing structures do not meet the requirements for safe use, and the house is partially in a dangerous state. Grade D indicates that the load-bearing structures no longer meet the requirements for safe use, and the entire house is in a dangerous state.