Air Leakage of Curtain Walls - Diagnostics and Remediation

This article demonstrates how monitoring of construction during a laboratory mock-up test was used to diagnose proneness to air leakage and to devise improved details. The curtain wall was built on a moveable, rigid frame that simulates the load-bearing structure. Construction details and components were identical to those used in actual buildings. The frame brings the curtain wall into contact with the test box, ensuring that the wall’s structural supports are not affected. Construction activities were monitored while the measurements included air flow rate versus air pressure difference across the wall, and horizontal deflections of wall mullions and beams. Locations of leakage points were detected using white smoke. The wall showed a density of air flow rate of 1.5 m3m-2h -1 at a pressure difference of ∼300 Pa, barely meeting the requirements for EN 12152 classification level A2. Correlating leakage points with detected construction weaknesses led to remedial actions by the manufacturer. The tests were repeated, revealing an improved air-tightness (density of air flow rate less than 0.6 m3m- 2h-1 at 350 Pa, and 0.8 m3m -2h-1 when extrapolated to 600 Pa), which meets the requirements for classification level E.