During the installation of aluminum curtain walls, controlling verticality and flatness is crucial for ensuring the overall structural stability and aesthetic quality of the curtain wall. Verticality deviations can lead to a loose connection between the curtain wall and the main structure, potentially causing deformation or leakage due to stress concentration after long-term use. Flatness deviations directly affect the visual appearance of the curtain wall, especially under lighting, creating an uneven appearance. Therefore, a comprehensive approach is needed, encompassing measurement and layout, frame installation, panel fixing, environmental factor control, and quality inspection, to form a systematic deviation control system.
Measurement and layout are fundamental to verticality control. The installation of aluminum curtain walls requires using the building's axis and elevation lines as a reference, establishing a three-dimensional control network using a total station and level. In practice, vertical control lines and horizontal grid lines must be marked on the main structure, and a "three-level verification" mechanism—team self-inspection, technical re-inspection, and supervisor acceptance—must be employed to ensure that the grid dimensions and elevation deviations are within acceptable limits. For irregularly shaped curtain walls or large-span structures, BIM technology can be introduced to simulate the installation process, optimize the layout plan, and avoid distortion of the curtain wall grid lines due to deviations in the main structure. For example, in one project, stress concentration occurred after the keel was installed because settlement joint displacement was not considered. This was later resolved by adding expansion joints, highlighting the importance of anticipating dynamic changes in the main structure during the layout stage.
The accuracy of the frame installation directly affects verticality and flatness. The frame of an aluminum curtain wall typically consists of columns and beams, and verticality and horizontality must be strictly controlled during installation. Column installation requires correction using a laser plumb line or plumb line to ensure that the verticality deviation across the entire height meets the specifications. Beam installation requires ensuring that the horizontal deviation between adjacent beams is within the allowable range, and temperature stress is released through expansion joint design. The robustness of the connection nodes is equally crucial. After tightening the bolts, spring washers should be added to prevent loosening, and welded areas must be cleaned of weld slag and coated with anti-rust paint to prevent frame deformation due to loose connections. For example, in one project, localized subsidence occurred later because the bolts connecting the beams and columns were not tightened properly; this was ultimately resolved by reinforcing the structure.
Panel fixing technology is the core of flatness control. Aluminum alloy panels must be installed using a floating connection method. Through a perforated design and adjustable PVC shims, slight displacement of the panels under temperature changes or seismic forces is allowed, preventing deformation due to stress concentration. During installation, a "three-point positioning method" must be used to adjust the panels, ensuring that the height difference and misalignment between adjacent panels are within acceptable limits. For large-area panels, reinforcing ribs must be added at folded edges or weak points to enhance wind pressure resistance. For example, in one project, the lack of reinforcing ribs caused panels to bulge under wind pressure; this was later repaired by adding reinforcing ribs.
Environmental factors have a significant impact on the installation accuracy of aluminum curtain walls. Temperature changes cause thermal expansion and contraction of aluminum alloy materials. If expansion joints are not provided or rigid connections are used, deformation is easily triggered. Therefore, when the curtain wall length exceeds a certain value, expansion joints must be installed and filled with elastic sealant to ensure airtightness while allowing for displacement. Furthermore, external conditions such as wind and sunlight can also affect measurement and installation accuracy. Laying out and calibration should be carried out during periods of lower wind speed, and shading measures should be taken to reduce thermal deformation. Quality inspection and acceptance are the final line of defense in deviation control. After the aluminum curtain wall is installed, it requires item-by-item and section-by-section acceptance, focusing on indicators such as verticality, flatness, and sealant quality. Acceptance standards typically require that verticality deviation not exceed the specified value, flatness deviation be within the allowable range, and sealant width be uniform without bubbles or cracks. Simultaneously, water spray tests and airtightness tests must be conducted to ensure the curtain wall's waterproof and sealing performance. Any problems discovered during inspection must be rectified promptly and re-inspected to ensure the curtain wall quality meets design requirements.
Verticality and flatness control of the aluminum curtain wall installation must be maintained throughout the entire process of design, construction, and acceptance. Through precise measurement and layout, strict frame installation, scientific panel fixing, reasonable environmental control, and meticulous quality inspection, deviations can be effectively reduced, ensuring the structural safety and aesthetic quality of the curtain wall.
