Spandrel Glass Breakage

Curtain wall design commonly uses insulating glass units for vision and spandrel glazing to provide better visual harmonization of building façade glass. Risks with this design approach include higher thermal stresses, especially when low-emissivity coatings are used on insulating glass units in spandrel areas. Ceramic enamel frit, commonly used to opacify spandrel glass, is known to induce a bending strength reduction of up to 40%. The ability of ceramic enamel frit coated glass to resist thermal stress is similarly reduced. Multiple incidences of thermal stress related fracture have occurred. Silicone spandrel glass coatings have been examined as a solution to prevent the strength reduction in heat-treated glass. Four-point bending tests were used to investigate the flexural strength of coated heat-strengthened and fully-tempered glass. Ball drop testing was used to investigate the impact resistance of coated fully-tempered glass. This presentation will give examples of breakage of ceramic enamel frit coated glass and the test program showing the benefits of silicone coated glass.

Learning Objectives:

  1. Understand what ceramic enamel frit glass breakage looks like.
  2. Understand the contributing causes of glass breakage. Can the causes be eliminated or reduced?
  3. Understand the differences in the approach between European standards and American standards to deal with glass breakage.
  4. Learn how to use silicone opacifiers to avoid glass breakage.

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George Torok, B.Tech., (Arch. Sci.), C.E.T., BSSO

George brings a unique breadth and depth of experience to every project, with over 30 years of experience in building enclosure design, construction, performance assessment, failure investigation and rehabilitation for public and private sector buildings of all types across North America.  George is a member of MH’s Façade Engineering Team, working with building owners and design teams to achieve balanced, practical and innovative solutions, and providing peer support and mentoring within MH.  His focus is fenestration technology, including low-rise residential windows, doors and skylights, high-rise residential window wall, commercial curtain wall and custom, one-of-a-kind glazed architectural structures.