Glass is a brittle material. It will act elastically until it fractures at ultimate load. That ultimate load will vary, depending upon the type and duration of the loads applied and the distribution, orientation and severity of the in homogeneties and micro-flaws that exist in the surface of the glass. Because of this nature, glass cannot be engineered in the same way as other building envelope materials that have a predictable, specific strength. In those cases, factors can be (and are) assigned to help assure that breakage does not occur at the selected design load. The Technical Services Division of the National Glass Association (NGA) has produced this Glass Technical Paper solely for informational purposes. This Paper was developed by dedicated member volunteers and subject matter experts. This document was originally published in 2012. This edition of the paper was updated and published in July 2023.