Assembly House Prefabricated Wall Opening

The construction plan for prefabricated wall openings in assembly houses mainly covers the prefabrication stage and the post-installation on-site opening stage. It is applicable to the reservation and post-opening construction of wall openings caused by design changes, equipment installation requirements, or production deviations of prefabricated components, involving prefabricated exterior wall panels, interior wall panels (including load-bearing and non-load-bearing), and other components. The opening size ranges from 100mm×100mm to 1500mm×2000mm.

Key Points for Construction in the Prefabrication Stage

1. Drawing Verification and Positioning: It is necessary to strictly verify the prefabricated component drawings against the mechanical and electrical installation drawings to clarify the location, size, quantity, and reinforcement avoidance requirements around the reserved openings. Emphasize marking the minimum safe distances between the openings and the component edges, reinforcements, and embedded parts: for load-bearing components, the edge of the opening should be at least 50mm away from the reinforcement; for non-load-bearing components, it should be at least 30mm to avoid affecting structural safety due to positioning deviations.
2. Mold Selection and Installation: The materials for reserved openings include steel or plastic molds. Steel molds should have a thickness of at least 3mm and a smooth surface without burrs to prevent damage to the components during demolding; plastic molds should have high-temperature resistance (≥80℃) and anti-aging properties to ensure they do not deform during concrete pouring and curing. The molds should be firmly fixed during installation to prevent displacement during concrete vibration.
3. Precise Positioning of Reserved Openings: For openings that need to penetrate on-site, such as ventilation shafts and pipe penetrations, precise positioning should be carried out during the mold stage using laser positioning or template opening techniques to avoid damaging the integrity of the components and reducing construction efficiency due to on-site opening.

Key Points for Construction in the Post-Installation On-Site Opening Stage

1. Structural Safety Assessment: Before post-opening, a structural engineer should calculate the impact of the opening on the load-bearing capacity of the component. When the opening size exceeds one-third of the component's cross-section, reinforcement measures such as reinforcement bars or steel sleeves must be added to ensure structural safety.
2. Opening Tools and Materials: The materials for post-opening include diamond cutting blades and water drill bits. The diameter of the cutting blade should match the opening size, and the hardness of the water drill bit should be ≥HRC60 to ensure cutting efficiency and quality. The reinforcement materials should meet strength requirements: the strength grade of ribbed reinforcement bars should be ≥ that of the original reinforcement in the component, and the strength grade of the grout should be ≥C40 with a flowability of ≥300mm to ensure reinforcement effectiveness.
3. Construction Process Control: Post-opening should be carried out according to the process of 'positioning → cutting → cleaning → reinforcement'. During cutting, vibration should be controlled to avoid damaging the surrounding concrete; after cleaning the opening, the exposure of reinforcement should be checked, and rust removal treatment should be carried out if necessary; the reinforcement bars should be reliably connected to the original reinforcement, and the grout should be vibrated in layers to ensure it works in conjunction with the component.