Commercial Housing Roof: Prefabricated Panel House

A commercial housing roof that is a prefabricated panel house typically refers to a building constructed primarily with prefabricated panels, commonly seen in older houses built in the early stages, possessing a specific historical background and structural characteristics.

Definition and Structure of Prefabricated Panel Houses

Prefabricated panel houses are structures where factory-made cement components (prefabricated panels) serve as the main load-bearing or partitioning elements. During the production of prefabricated panels, wooden molds are nailed together, steel bars are arranged, and cement is poured to form the panels, which come in two types: solid and hollow. Solid panels have higher strength, while hollow panels reduce self-weight and save materials through internal cavities. This structural form was widely adopted during a specific historical period (such as the 1970s and 1980s), primarily for quickly addressing the housing needs of employees.

Historical Background and Construction Characteristics

The popularity of prefabricated panel houses was closely related to the social demands of the time. In the 1970s and 1980s, China faced a severe housing shortage. Government agencies, public institutions, and state-owned enterprises adopted the low-cost, rapid-construction approach of prefabricated panel houses to solve the housing problem for their employees. Factory-made components could be standardized and assembled on-site with high efficiency, significantly shortening the construction period. For example, a multi-story residential building might be completed in just a few months, much faster than traditional cast-in-place structures.

Defects and Limitations of Prefabricated Panel Houses

Although prefabricated panel houses played an important role at the time, their structural defects gradually became apparent:

• Short Service Life: As cement components, prefabricated panels are susceptible to environmental erosion (such as freeze-thaw cycles and carbonation) over time, leading to rusting of steel bars, cracking of concrete, and a decrease in structural load-bearing capacity. Their typical design life is 30-50 years, shorter than the over 70 years of cast-in-place structures.
• Poor Seismic Performance: Prefabricated panels are connected to the main structure through nodes, resulting in weak overall integrity. Under seismic action, these nodes are prone to damage, causing panel detachment or building collapse. For example, during the 2008 Wenchuan earthquake, some prefabricated panel houses suffered severe damage due to node failure.
• Ground Water Seepage Issues: Gaps exist at the joints of prefabricated panels. If waterproofing is not properly handled, rainwater can easily seep into the interior, causing mold on walls and deformation of floors. Additionally, if the internal cavities of hollow panels are not sealed, they can also become channels for water seepage.

Replacement Trend in Modern Architecture

With advancements in building technology, newly built commercial housing has basically adopted cast-in-place slab structures since 2003. Cast-in-place slabs are formed by on-site formwork erection, steel bar binding, and concrete pouring, creating an integral structure with good overall integrity, strong seismic resistance, and high durability, gradually replacing prefabricated panels as the mainstream choice.