Children’s Health Dallas Campus – Skybridge Assessments

Title: Children’s Health Dallas Campus – Skybridge Assessments

Award Category: Exterior Wall

Project Address/Location

1935 Medical District Drive

Dallas, Texas 75235
United States

Submitted By: Bryan Staffel

Company Info

Wiss, Janney, Elstner Associates, Inc.

6363 N. State Highway 161 Suite 550

Irving, Texas 75038
United States

2108638147

[email protected]

Project Description and Background: The Children’s Health (CH) Dallas campus includes three skybridges that are used to facilitate pedestrian foot traffic across roadways and train tracks, connecting various parking garages and hospital buildings. The three skybridges were constructed between 2003 and 2007, with lengths between 185 and 240 feet. Each bridge features aluminum-framed windows, metal wall panels, and sloped standing seam metal roofs. The structural steel trusses for the skybridges run along the exterior walls, outside the pedestrian enclosure. Ongoing water intrusion issues were reported at several of the skybridges, primarily associated with fenestrations, terminations at adjacent buildings and roof-to-wall transitions. WJE was engaged to perform a condition assessment and water intrusion investigation for the three skybridges. One of the significant challenges for this project was access due to the height of the skybridges and the presence of active public streets or railroad tracks below. The local railroad authorities require special trainings, certifications, and coordination to be within or above a tracks fouling zone. In addition, significant costs and coordination are needed to partially close public streets.

Scope: WJE’s scope of services included an interior and exterior visual assessment and water intrusion testing at each skybridge. Up-close exterior observations and water testing were made by WJE’s Difficult Access Team. Traditional access methods, suspended scaffolding, aerial lifts, crane-suspended platforms, etc. were determined to be impractical or inadequate given the configuration of the structure, the site limitations, and cost/schedule limitations. Our Difficult Access Team (composed of engineers, architects, and technicians) was able to perform up-close observations and testing along the skybridges using industrial rope access techniques in combination with a specialty rail system. Water intrusion testing was conducted in general accordance with ASTM E2128 - Standard Guide for Evaluating Water Leakage of Building Walls. WJE used a calibrated spray rack in general accordance with ASTM E1105 - Standard Test Method for Field Determination of Water Penetration of Installed Exterior Windows, Skylights, Doors, and Curtain Walls, By Uniform or Cyclic Static Air Pressure Difference (no differential pressure was used) and a calibrated spray nozzle in general accordance with AAMA 501.2 (3) - Quality Assurance and Diagnostic Water Leakage Field Check of Installed Storefronts, Curtain Walls, and Sloped Glazing Systems. As our testing was diagnostic in nature, testing outside of the methods specified by these standards was employed in some instances. WJE used various water pressures and test durations as determined appropriate for the component or material being tested. WJE issued a report of our findings and also developed repair documents to address the identified deficiencies related to water intrusion and/or general deterioration of enclosure components. WJE provided construction observations services during repairs to ensure that our design was properly implemented.

Solution: Our water intrusion investigation review several deficiencies within the building enclosure including missing/deficient sidewall transition flashings, discontinuities within internal seals at mechanical louvers, missing/failed sealant joints, and window gasket deficiencies. Other general items of noted deterioration or damage (unrelated to water intrusion) included broken spandrel glass, failed IGUs, expansion joint deficiencies, and inefficient window drainage. Based on the results of our assessment and testing, short- and long-term repair considerations were presented to the client for consideration. WJE’s repair solutions primarily included removal and replacement of existing components. The uniqueness of this repair scope was related to access. Several of the repair solutions needed to be implemented from rope or other specialty access. At a few locations, exterior replacements methods were not possible from the exterior (isolated glass replacement, louver modifications, etc.). WJE worked with the project team to develop access methods and repair solutions that were achievable from the interior that still maintained a water-tight enclosure.

Value: The use of a building enclosure consultant was extremely valuable to the success of this project. The initial assessment and water testing was critical to evaluating the condition of the skybridges and developing the appropriate repair methods. Given the difficulty of access to implement repairs, the designed solutions needed to be accurate and constructible. WJE was able to access and evaluate the skybridges quickly and efficiently with the use of our difficult access team saving the client time and money (as opposed to traditional access methods). WJE’s project team included six IIBEC members that contributed to the observation, testing, design, and implementation of repairs at the skybridges.

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