Evaluation Grades of Prefabricated Panel Houses
The evaluation grades of prefabricated panel houses can be classified into four grades, namely A, B, C, and D, according to the 'Standards for the Appraisal of Dangerous Houses', as follows:
Grade A: Houses of this grade have no dangerous components, and their structures fully meet the requirements for safe use, with all functions in normal condition. Such houses only require routine maintenance, such as regularly inspecting various components of the house, lubricating and cleaning easily worn parts to ensure the house remains in good condition for a long time. Structures like the walls, roof, doors, and windows of the house are intact, with no cracks or deformations. Facilities such as water and electricity lines also operate normally, posing no safety hazards to the occupants' lives.
Grade B: Houses of this grade have minor defects in individual components, but these defects do not affect the safety of the main structure, and the house's functions are basically intact. Common minor defects include fine cracks in non-load-bearing walls, which may be caused by factors such as natural settlement of the house or temperature changes, generally having little impact on the overall structure of the house; occasional water leakage at the joints of prefabricated panels, which may be caused by inadequate waterproofing or aging of the sealing materials at the joints, and can be resolved through simple repairs; slight sagging of the floor in some local areas that is not visible to the naked eye, indicating that the load-bearing capacity of the floor is still within the normal range, with only minor deformations.
Grade C: When 5% ≤ R < 25%, and the number of floors with a dangerousness grade of Du does not exceed (F + B + f)/3, the dangerousness grade of the house is rated as Grade C; otherwise, it should be rated as Grade D. Here, R usually refers to the ratio of the number of dangerous components in the house to the total number of components in the house, and F, B, and f represent parameters related to the number of floors with different degrees of danger. A Grade C house means that some load-bearing structures do not meet the requirements for safe use, and the house as a whole is in a dangerous state, constituting a whole-building dangerous house. For example, some load-bearing walls of the house have obvious cracks with relatively large widths and lengths, which may affect the load-bearing capacity of the walls; the prefabricated panels have severe sagging deformations, resulting in an uneven floor surface and even cracking.
Grade D: When R ≥ 25%, the dangerousness grade of the house is rated as Grade D. Houses of this grade have some load-bearing structures that do not meet the requirements for safe use, and the house is in a dangerous state locally, constituting a partially dangerous house. For example, a certain load-bearing column of the house is severely damaged, resulting in a significant decrease in its load-bearing capacity, which may cause local collapse of the house; or the roof structure of the house is severely damaged over a large area, unable to withstand normal loads, with problems such as rainwater leakage, affecting the normal use and safety of the house.
