The Los Angeles skyline has transformed dramatically over the past two decades, with a wave of high-rise residential, hotel, and mixed-use towers rising across Downtown, Hollywood, Century City, and the Wilshire corridor. The building envelopes on these towers are overwhelmingly curtain wall systems — unitized or stick-built assemblies of aluminum framing and glass that form the entire exterior skin of the building. When these systems perform correctly, they provide a seamless, weather-tight enclosure. When they fail, the consequences are amplified by the height, scale, and exposure conditions unique to high-rise construction.
Water infiltration through curtain walls is the most common building envelope complaint in Los Angeles high-rises. But curtain wall failures also include air leakage, condensation, glass breakage, gasket deterioration, and thermal performance degradation — all of which can affect occupant comfort, energy costs, and long-term building value.
How Curtain Walls Work
A curtain wall is a non-load-bearing exterior wall system that hangs from the building's structural frame like a curtain. It must resist wind loads, manage water, control air infiltration, provide thermal insulation, and accommodate building movement — all while being as light as possible to minimize structural demands.
Modern curtain walls manage water through a combination of strategies. The outermost glass and aluminum surfaces form the primary weather barrier. Behind the glass, a system of gaskets, pressure-equalized cavities, internal gutters, and weep holes manages any water that penetrates the primary seal. The system relies on the principle of pressure equalization: by allowing the air pressure in the cavity between the outer glass and the inner seal to equalize with exterior wind pressure, the driving force that pushes water through joints is neutralized.
This is an elegant system when properly designed and installed. But it depends on the integrity of dozens of gaskets, seals, and drainage paths within every curtain wall unit — and on the precision of the connections between units.
Common Curtain Wall Failures
Gasket and Seal Degradation
The primary weather seals in a curtain wall are EPDM or silicone gaskets that compress against the glass or against adjacent framing members to create water and air barriers. Over time, these gaskets lose elasticity, shrink, harden, and develop compression set — permanent deformation that reduces their sealing force. In Los Angeles, UV radiation and thermal cycling accelerate gasket degradation. Wet-applied silicone sealant joints at perimeter conditions and between units are subject to the same adhesion and cohesion failures that affect sealant joints in any facade system.
Internal Drainage Failures
When exterior gaskets admit water — which all curtain walls are designed to tolerate to some degree — the internal drainage system must capture and evacuate that water before it reaches the interior. Aluminum sill members, internal gutters, and weep slots direct water downward and outward. Blockages from construction debris, sealant overflow, or displaced gaskets can dam water within the system, causing it to overflow at unintended locations. On tall buildings, pressure differentials between floors can push water upward through the system rather than allowing it to drain downward.
Stack Joint and Movement Joint Failures
High-rise buildings undergo significant vertical movement from concrete creep and elastic shortening, lateral sway from wind loads, and inter-story drift from seismic events. Curtain wall systems accommodate this movement at stack joints (horizontal joints between floor levels) and at connections to the structure. These joints must allow controlled movement while maintaining weather integrity. When stack joint gaskets are improperly detailed, when structural connections are too rigid, or when the anticipated movement range is exceeded, water and air leakage result.
Los Angeles high-rises must accommodate seismic inter-story drift requirements per CBC and ASCE 7. Curtain wall systems tested to AAMA 501.4 for seismic displacement must demonstrate that they can undergo the design drift without glass fallout or loss of weather performance. Buildings with curtain walls that were not tested or designed to adequate drift levels face heightened risk during seismic events.
Glass Breakage
Spontaneous glass breakage in curtain walls — glass panels fracturing without apparent external cause — occurs with enough frequency in Los Angeles high-rises to warrant attention. Nickel sulfide inclusions in tempered glass can cause delayed fracture, sometimes years after installation. Thermal stress fracture occurs when differential temperatures across a single glass panel — caused by partial shading, spandrel conditions, or adjacent heat sources — exceed the glass's thermal stress resistance. Wind-borne debris impact, frame distortion, and improper glazing that places point loads on the glass edges are additional causes. For more, see Metal Panel Cladding Failures in California.
Investigation of High-Rise Curtain Wall Failures
Investigating curtain wall failures on high-rise buildings presents unique logistical challenges. Exterior access requires swing stages, bosun's chairs, or rope access technicians. Interior access may require tenant coordination across dozens of floors.
Water testing of curtain walls follows AAMA 501.2 (field-applied nozzle spray test) or ASTM E1105 (calibrated spray rack test). These tests are applied systematically at representative locations and at areas of reported leakage to identify specific failure points. Air leakage testing per ASTM E783 quantifies infiltration rates and identifies locations where gaskets or seals have failed. Infrared thermography from the interior reveals thermal anomalies associated with air leakage paths and moisture infiltration.
Managing Curtain Wall Performance
Building owners and property managers should recognize that curtain wall systems require ongoing maintenance. Gasket and sealant replacement cycles, drainage system cleaning, and periodic water testing are necessary to sustain performance over the building's service life. When leaks or performance complaints arise, engaging a building envelope consultant with specific curtain wall expertise ensures accurate diagnosis and effective remediation.