Recent changes in building codes, particularly to the 2015 International Building Code (IBC), are driving increased interest in and use of laminated glass in railings and balustrades.
Valerie Block with Kuraray led the discussion on this topic last week, as part of the “Security, Fire-Rated and Laminated Glazing” technical sessions, during GlassCon Global 2016 in Boston.
“Laminated glass has become the go-to glass product for railings in North America in the last couple years,” said Block. She explained that the industry, especially the laminating division within the Glass Association of North America, has been spending a lot of time discussing and addressing these issues.
Block said one thing they’ve looked at is how to distinguish between interlayers, as there are both flexible and stiff interlayers. This, she added, is being defined in the new Canadian standard on glass railings, which is in the final stages of development.
She explained that the need for and interest in using laminated glass started with several instances of breakage in North America when it fell and injured people below.
She said in Canada they are looking more at heat-soak testing as one possible way to improve the odds of glass breaking. Nothing, however, is happening at the U.S. at this time in terms of heat-soak testing codes or standards.
Block also pointed out that while the IBC does now call for the use of laminated glass in most railing/balustrade applications, it is a model code.
“So unless adopted—and this provision specifically—it’s not a regulation,” she said. “But we do see more who are moving toward laminated glass in anticipation of adoption of this code.”
The code addresses both handrails and guards. Guards, she explained, imply there is a drop on the other side of the panel, so there’s more of a safety risk with the guard application compared to handrails.
Before the 2015 code change, tempered or laminated glass could be used in these applications. The code change removed that option except in limited locations. These include where the railing has some type of permanent structure below it that would prevent someone from becoming injured or where there is no walking surface below it.
Block also talked some about flexible vs. stiff interlayer products. When determining which to use, she said a lot depends on how the glass is being supported.
She also noted that quality requirements may require further discussion between specifier and fabricator.
Block concluded by saying the industry is seeing a rapid transformation from monolithic to laminated glass and the need is to manage expectations and improve quality.
Wim Stevels, Eastman Chemical, also discussed laminated glass in his presentation on structural PVB interlayers. He brought a slightly different perspective since the use of laminated glass in railings has been common in Europe for a long time. He took a look at structural PVB interlayers as well as the relevance of the properties of glass design.
Stevels discussed recent balustrade panel testing; configurations were based on conventional and structural PVB. The study found that the use of structural PVB results in lower deflection compared to conventional PVB, resulting in higher forces to break the glass.
The presentation noted that structural PVB interlayers can offer new application opportunities in laminated safety glass. For example, this could include annealed glass in balustrades and/or the introduction of color functionality with these structural PVB interlayers.