Prefabricated Panels for House Roofs
The use of prefabricated panels for house roofs was a common practice in early 20th-century construction, but it has issues such as easy cracking at joints, weak earthquake resistance, and poor sound and heat insulation. The service life is approximately 30 - 50 years, and it is gradually being replaced by cast-in-place concrete and prefabricated buildings. The treatment measures need to be taken according to the safety level of the house.
Prefabricated panels are concrete prefabricated components produced and processed at a prefabrication yard. During production, a hollow mold is first made by nailing wooden boards, and then steel bars are placed in the hollow part of the mold. After that, the mold is filled with cement. Once dry, the wooden boards are knocked off to obtain the finished product. They are divided into two types: solid and hollow. The hollow structure achieves lightweighting by reducing the non-load-bearing concrete.
Prefabricated panels have many drawbacks. The joints between two floor slabs are prone to cracking, affecting the structural stability and waterproofing performance of the house. Their earthquake resistance is weak. In the event of natural disasters such as earthquakes, they are difficult to effectively resist the seismic forces, which may pose a threat to the lives of the occupants. Their sound and heat insulation performance is also poor, failing to provide a quiet and comfortable indoor environment for the occupants. Generally, the service life of houses with prefabricated panels is about 30 - 50 years, and the performance of the house will gradually decline over time.
With the development of construction technology, cast-in-place concrete and prefabricated buildings are gradually replacing traditional prefabricated panel houses. Houses built with cast-in-place structures have better integrity and are sturdier, effectively avoiding problems such as joint cracking in prefabricated panels, and have better performance in terms of earthquake resistance, sound and heat insulation.
Currently, the treatment of prefabricated panel houses is being promoted. According to the house safety appraisal report, houses are divided into four levels: A, B, C, and D, and the disposal paths vary depending on the level. For houses at Level A or B with no major problems in the main structure, the most practical solution is the renovation of old residential areas, such as roof repairs, pipe replacements, fire protection rectifications, and elevator installations. For Level C dilapidated houses with repair potential, they enter the repair and reinforcement path, which includes strengthening the walls, beams, columns, floor slabs, and foundations, as well as improving earthquake resistance. As for expropriation and demolition, what truly determines whether a house can be demolished is not how old it is, but whether there are projects in your area, such as road construction, subway construction, public facility construction requiring land, or if the area is included in a clear demolition and reconstruction project, only then can the expropriation process be carried out in accordance with the law.
