House Type - Cast Prefabricated Panel

A typical representative of house types constructed primarily with cast prefabricated panels is the prefabricated panel house, with its core features, performance characteristics, and application scenarios as follows:

I. Definition and Structure of Prefabricated Panel Houses

Prefabricated panel houses are structures built using cement components (prefabricated panels) produced in factories as the main load-bearing or enclosure elements. Prefabricated panels are made by nailing wooden models, arranging steel bars, and pouring cement, and are classified into solid and hollow types:

• Solid prefabricated panels: Cast as a whole, they have strong load-bearing capacity but are heavy, mostly used for floor slabs or roof panels in early low-rise residential buildings.
• Hollow prefabricated panels: Achieve lightweighting by reducing non-load-bearing concrete, with internal reserved holes to reduce weight and save materials. However, due to poor earthquake resistance, their use in building structures is no longer recommended. Modern buildings more commonly adopt cast-in-place structures or prefabricated modules.

II. Origin and Construction Characteristics of Prefabricated Panel Houses

Prefabricated panel houses originated in the early 20th century, with most residential buildings constructed in China before 1985 using this type of structure. Their construction method has distinct era characteristics:

• Factory prefabrication + on-site installation: Prefabricated panels are produced in factories to standard specifications and then transported to the site for assembly. Construction speed is fast, but joint treatment is complex, requiring methods such as mortar filling and steel bar welding to ensure structural integrity. Waterproofing and structural issues are construction challenges.
• Technical limitations: Early prefabricated panel houses had weak connections between prefabricated components, resulting in lower overall integrity compared to cast-in-place structures, leading to poor earthquake resistance and susceptibility to joint cracking or component detachment during earthquakes.

III. Performance Characteristics and Service Life

Existing prefabricated panel houses generally have the following issues:

• Structural performance: Weak earthquake resistance, poor sound insulation and thermal insulation, and due to component aging, their service life is approximately 30-50 years. After exceeding the design life, evaluation for reinforcement or demolition is required.
• Hollow panel risks: Although the hollow structure reduces weight, load-bearing capacity decreases. If used in high-rise buildings or areas with heavy loads, there are safety hazards.
• Modern improvements: Modern prefabricated buildings significantly enhance earthquake resistance through steel-concrete composite modules and integral casting techniques, reducing construction time by 30% compared to traditional methods, but they no longer fall within the scope of traditional prefabricated panel houses.

IV. Application Scenarios and Policy Orientation

• Residential sector: Since 2022, China has implemented renovation policies for prefabricated panel houses, focusing on repair and renovation, with emphasis on structural reinforcement, pipeline updates, and improvement of sound insulation and thermal insulation performance; only buildings that meet the criteria for dangerous houses are demolished. Some regions have initiated demolition work for prefabricated panel houses, gradually replacing them with safer residential forms.
• Non-residential sector: Prefabricated panels are still used in scenarios with low structural requirements, such as ditch covers beside highways and roof insulation layers, leveraging their advantages of low cost and easy installation.

Summary: Prefabricated panel houses are products of a specific historical period, characterized by high construction efficiency but limited performance. They are gradually being replaced by prefabricated buildings or cast-in-place structures in modern construction. For existing prefabricated panel houses, repair or demolition measures should be taken based on structural safety conditions to ensure residential safety.