How does a unitized curtain wall ensure water tightness and air infiltration control?

Water tightness and air infiltration control in unitized curtain walls are achieved through layered defense: precision factory gasketting, mechanical drainage paths, pressure-equalized cavity design, and field sealing at panel interfaces. In the factory, primary weather seals (compression gaskets) and secondary silicone or polyurethane sealants are applied to critical joints; pre-glazed IGUs are seated on setting blocks and captured with internal pressure plates and secondary seals. Panels are designed with internal drainage channels that collect incidental water penetration and route it to designated weep points. At the building interface, vertical and horizontal panel joints incorporate overlap or tongue-and-groove features, with back-members and cap systems ensuring continuity of the weather barrier. Pressure-equalization strategies—where the panel cavity is allowed to equalize pressure with ambient air—reduce the driving force for water ingress through the outer joint. Air infiltration control is maintained by continuous gasketing, sealed internal mullions, and minimizing gaps at interface points. Critical to effectiveness is factory quality control (consistent sealant bead size, compression set of gaskets) and correct on-site erection sequencing that prevents stretching or misalignment of seals. Post-installation testing—air infiltration tests (per industry standards) and water penetration tests (static and dynamic) on mock-ups and production areas—verifies performance; failed tests require corrective sealing, flashing adjustments, or panel rework. Routine maintenance of drainage weep holes and replacement of aged seals preserves long-term watertightness.