Glass Spandrels and Shadow Boxes: Design and Construction Considerations

Glass Spandrels and Shadow Boxes: Design and Construction Considerations

Glass spandrels are a common design strategy utilized to opacify floor levels in building facades. These assemblies are integrated into glazing systems to provide visual continuity with adjacent vision glass, rendering an all-glass look to the building facade. Although simple in concept, the physics and technical design considerations of glass spandrels and shadow boxes can be quite complex and must be carefully considered. These include the potential for heat build-up in the cavity; glass differential thermal stress; risks of cavity condensation; thermal performance; air, water, and vapor seal; edge-of-slab fire-safing; and accumulation of dust and debris in the cavity, to name a few. Project-specific exterior climate and interior psychometric conditions (i.e., temperature and relative humidity) must also be considered. In addition, glass spandrel design must consider the method of construction of the glazing system. Temporary protection during storage, transportation, and installation, as well as in-service considerations such as glass replacement, must also be factored into the equation. In this webinar, we will provide a summary of these important design and construction considerations, including a discussion on the longstanding industry debate “to vent or not to vent” glass spandrel assemblies.


After attending this webinar, participants will be able to:

  • Understand the basic components of spandrel assemblies.
  • Differentiate between the main types of glass spandrel assemblies.
  • Understand the key technical design considerations of spandrel assemblies.
  • Discuss key construction considerations of spandrel assemblies.

Participants will earn 1.0 AIA CES Learning Unit (LU/HSW) for attending the live webinar. Registration is free. Please note that space is limited – email events@sgh.com to join our waitlist if the session is closed when you register. 

About the Speaker

John  Jackson
John Jackson | Associate Principal

John Jackson specializes in facade and building enclosure design, combining his degrees in both architecture and structural engineering. He applies his creative and technical skills to designing and engineering innovative enclosure systems, having worked on a wide variety of projects both domestically and abroad, with particular expertise in curtain walls, custom glazing systems, structural glass, and glass investigations. John is an active member of the ASTM Subcommittee E06.52 on Glass Use in Buildings and regularly lectures on building enclosure design. In addition, John is part of an industry research project for the Charles Pankow Foundation, led by SGH, studying thermal performance of spandrel assemblies in glazing systems, including analytical modeling and empirical testing, endeavoring to address unknowns within the industry to help inform and develop future standards and codes.