International Code Council (ICC) public comment hearings ended yesterday in Las Vegas, and a proposed code change regarding glass loads was not approved. Proponents of S 193-19, including Trex Commercial Building Products, sought to revise the 2018 International Building Code (2407.1.1 Loads) as follows: “The glass panels and their support system shall be designed to withstand the loads specified in Section 1607.8. Glass guard elements panels shall be designed using a factor of safety of four applied to the modulus of rupture.”
The reason for the proposal, as submitted by the proponents, included the rationale that: “Allowable glass stress is traditionally determined by probabilistic methods (ASTM E1300) given particular load durations. The allowable stress decreases with a longer duration load (thus the factor of safety increases). Therefore the allowable stress calculated per ASTM E1300 effectively contains a factor of safety … The factor of safety of four should only be applied to glass. All other components supporting glass should be designed using the factors of safety provided in relevant material codes (AISC 360 for steel, etc.) … In summary, changing this language removes ambiguity, makes guard design more consistent with other similar systems, and saves money by lowering factors of safety for supports (to those that are used by the relevant material codes).”
The Glazing Industry Code Committee (GICC) opposed the proposal as it would have changed the loads that a glass panel/baluster in a guard must be able to withstand, according to Thomas Zaremba, who represented the GICC at the hearings.
“As currently written, glass guard panels/balusters are required to be designed using a factor of safety of four,” he said. “As approved by the ICC’s Technical Committee, this proposal would have applied that factor of safety to the ‘modulus of rupture’ of the glass. GICC opposed this change primarily because the proposal failed to provide any standard by which to determine the modulus of rupture. Secondarily, we opposed it because the ‘modulus of rupture’ can vary depending on a variety of factors, including the method of cutting used when the glass is cut to size.
Zaremba added that the decision for disapproval will be the subject of an online vote of the ICC membership across the country.
“That vote, when it is published sometime next month, will be final,” he said. “Those voters will all have access to the proposal, the supporting written statements, GICC’s written opposition and video recordings of the oral arguments given by both sides at the Technical Committee hearings and at the Public Comment hearings that lead to the Membership vote of 53 to 123.”