The waterproofing design of the exposed-frame joints in double-glazed, insulated, tempered glass exposed-frame curtain walls is crucial for ensuring the long-term stability of the curtain wall system. Its design must balance structural safety, watertightness, durability, and ease of construction.
Material selection is fundamental to waterproofing design. Sealing materials with excellent weather resistance, UV resistance, and aging resistance are required for exposed-frame joints in double-glazed, insulated, tempered glass curtain walls. For example, silicone structural sealants must possess high elasticity and low modulus to accommodate thermal expansion and contraction between the glass and aluminum profiles. Weather-resistant sealants must withstand long-term outdoor exposure and prevent cracking or powdering due to UV exposure. Furthermore, the aluminum profile surface should be treated with anodizing or fluorocarbon spraying to enhance coating adhesion and corrosion resistance, preventing seal failure due to profile rust. Furthermore, the butyl sealant and polysulfide sealant in the insulated glass must form a double seal to ensure airtightness and watertightness within the hollow layer.
The structural design must adhere to both the "isobaric principle" and the "rain curtain principle." Exposed frame joints typically utilize a dual-sealing structure: silicone structural sealant on the inside permanently bonds the glass to the aluminum profile, while weather-resistant sealant on the outside creates a secondary waterproof barrier. The design must ensure an isobaric cavity is formed between the two sealing lines. Isobaric holes or drainage channels maintain internal and external pressure balance, reducing wind pressure impact on the sealant. Furthermore, the drainage channels of the exposed frame aluminum profiles must be designed with a suitable slope to ensure that rainwater that infiltrates the isobaric cavity can be quickly drained through the drainage holes, preventing water accumulation and leakage. For example, unitized curtain walls often feature water-shedding strips at the horizontal and vertical joints, creating a continuous rain curtain to prevent rainwater from intruding into the structure.
Construction techniques play a crucial role in waterproofing effectiveness. Strict dimensional accuracy is required during aluminum profile processing to ensure uniform assembly gaps between the glass and the profile, avoiding gaps that could lead to incomplete sealant filling. During sealant application, the substrate surface must be thoroughly cleaned to remove oil, dust, and loose particles, and a primer should be applied to enhance adhesion. During the glue injection process, maintain a consistent glue gun speed to ensure full, bubble-free glue joints and that the glue joint thickness meets design requirements. Furthermore, the exposed frame aluminum plate should be installed using a continuous crimping method to avoid segmented crimping that may result in discontinuous sealing. After installation, a water spray test should be conducted to verify waterproofing performance and promptly identify and repair leaks.
Detailed attention is crucial to waterproofing design. Corners where exposed frame connections meet should be prefabricated with angle brackets or welded to ensure structural strength and sealing. Opening sashes should be designed with multiple layers of sealing strips, drain holes, and dust covers to prevent rainwater backflow. Furthermore, the joints between the top of the curtain wall and the parapet, and between the bottom and the floor, should be sealed with waterproofing membrane or sealant to form a continuous waterproof layer. Furthermore, flexible materials, such as rubber waterstops or sealing strips, should be used for waterproofing at expansion joints to accommodate structural deformation.
Post-maintenance is a long-term measure to ensure waterproofing performance. Regularly inspect the sealant for aging and promptly reapply or replace any cracked strips. Glass or profiles that have been impacted by external forces must be repaired or replaced immediately to prevent structural damage and seal failure. Additionally, debris must be removed from the gutter to ensure unimpeded drainage.
Collaborative design is an effective way to improve waterproofing performance. The waterproofing design of an exposed-frame curtain wall with double-glazed glass must be considered in conjunction with structural, thermal, and energy-saving systems. For example, optimizing the spacers and molecular sieve dosage in the insulating glass can reduce the risk of condensation in the insulating layer. Adjusting the cross-sectional design of the aluminum profile can minimize thermal bridging and prevent sealant cracking due to temperature differences.
The waterproofing design of the exposed-frame connection joints of an exposed-frame curtain wall with double-glazed glass requires a comprehensive approach encompassing six dimensions: materials, construction, construction, details, maintenance, and coordination. Only through scientific material selection, meticulous construction, standardized construction, and regular maintenance can the curtain wall system's long-term waterproofing performance be ensured in complex climatic conditions.
