Glass and Glazing Related Codes Undergo Vote at ICC Public Hearings

A number of code change proposals relating to glass and fenestration products were on the agenda during the International Code Council (ICC) hearings, which took place in October in Las Vegas. Changes clarifying the use of skylights and retention screens, as proposed by the American Architectural Manufacturers Association (AAMA), were approved as modified by the public comment to S190-19. However, a proposed code change regarding glass loads was not approved.

SLOPED SKYLIGHTS, ROOFS AND WALLS

International Building Code (IBC) section S190-19 applies to installation of glass and other transparent, translucent or opaque glazing materials installed at a slope of more than 15
degrees from the vertical plane. These include glazing materials in skylights, roofs and sloped walls.

Current code language explaining when screens are required below unit skylights and sloped glazing has been difficult for users to interpret, according to AAMA. Glaziers are incorrectly told they need to install a glass retention screen below conforming (30-mil interlayer) laminated glass, according to AAMA. Skylight and sloped glazing system manufacturers are often asked to intervene to ensure that unsightly, unnecessary screens—which decrease daylighting—are not installed in these instances.

In testifying on behalf of AAMA, Jennifer Hatfield said the public comment to the proposed code change clearly states that laminated glass with a 30-mil interlayer does not require screens.

“Calling that out more clearly in section 2405.2 should reduce the frequency of code misinterpretations,” Hatfield said.

In other action, to reduce redundancy in code language, AAMA proposed a change to S191-19 that would have removed a line in Section 2405.2 —the sloped glazing section—pointing code users instead to Section 2110.1 for glass-block construction requirements. The line also exists in the safety glazing section of the code, which AMAA members felt was a more applicable location. Public comment hearing voters opted to keep current language intact and disapproved the S191-19 proposal.

“Earning approval on the more significant proposal, S190-19, will make it easier to determine when screens are and are not required below skylights,” said AAMA codes and regulatory affairs manager Kathy Krafka Harkema. “That’s a big improvement for code enforcement officials, those who construct and occupy buildings, and the skylight industry.”

GLASS LOADS PROPOSAL

Proponents of S 193-19, including Trex Commercial Building Products, sought to revise the 2018 IBC (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.”

Proponents of the proposal say, “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.) …”

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 with-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 [in December], 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.”

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