Glazed Curtain Wall
ABBAE is able to test and verify commissioning of all types of glazing. The most common types of glazing used today, are glazed curtain walls, which offer more interior space than traditional wall bearing construction, and are less expensive.
Common glazing failures are found in the glass itself, sealants, gaskets, and other glazing materials, which can result in water and air infiltration. It is important that all written instructions of manufacturers of glass, sealants, gaskets, and other glazing materials are complied with. ABBAE can conduct an investigation of the glazing and glazing materials to determine the source of failure. ABBAE cannot only test for failures, but also offers repair and replacement services.
Glazing Evaluation and Testing
If leaks, deflection, etched glass, or other issues have become a concern, ABBAE can conduct a systematic evaluation of the curtain wall system, beginning with close visual inspection. ASTM provides test standards for the evaluation of air and water penetration, as well as structural performance of glass in curtain wall applications. Tests for water penetration, such as ASTM E1105, use a calibrated spray rack system with a positive air pressure differential to simulate wind-driven rain. ASTM E783 specifies test procedures for determining field air leakage at specific pressures.
Glazing that displays systematic scratches or other defects after installation may need to be evaluated for structural integrity. In such cases, a representative sample of glass units may be removed and tested under laboratory conditions. ASTM E997 is one test method for determining the probability of breakage for a given design load.
Common Glazing Failures
Water Infiltration – Water infiltration creates premature deterioration of the wall structure, finish damage, mold and mildew, and decreased interior air-quality. Sealant failure can cause water infiltration if they break apart or shrink with age.
Condensation – Condensation occurs when the temperature of the glass or aluminum frame in a curtain wall reaches the dew point temperature of the interior space conditions. Basic design against condensation of a curtain wall section is based off of the expected temperature and humidity of the space.
Deflection – Aluminum is a common glazed curtain wall framing material, however it deflects approximately three times as much as steel. This poses a danger in that the glass may be forced out of place.
Poor Thermal and/or Visual Performance – Condensation may also be an indicator to failure of the curtain wall system. If moisture is observed between panes of glass in an IGU, the hermetic seal may have failed, permitting air intrusion into the interstitial space and compromising thermal and visual performance.
Design, Construction, and Installation Defects – A common defect here are missing, incorrectly applied, or otherwise deficient sealants at frame corners and other intersections can lead to serious water infiltration issues. Failure on the part of the contractor to follow manufacturers’ guidelines, and on the part of the design professional to provide sufficient oversight, can result in water damage.
Roller Wave Distortion – When the glass width dimensions are greater than the width of the furnace conveyor, the resulting heat treated product, when installed, will exhibit vertical roller wave distortion. Specify using ASTM C1651 Standard Test Method for Measurement of Roll Wave Optical Distortion in Heat-Treated Flat Glass.
Field Investigation of Glazed Curtain Wall