Laminated glass gives architects and designers the ability to improve safety and sound attenuation. It can also provide strength and the means for artistic expression. With a number of possible functions of laminated glass beyond just transparency and daylighting comes many misconceptions. Lamination experts are shedding light on the truth behind these misconceptions.
Misconception: Fully Tempered Glass is the Only Safety Glass
Julia Schimmelpenningh, industry technical manager for architectural products at Eastman Chemical Co., says one misconception is that tempered glass is the only safety glass.
“Many times, in marketing and informational brochures from some associations and organizations you will see reference to safety glass (fully tempered) or tempered safety glass as the only material that complies with codes,” she explains.
In the correct configuration laminated glass also is safety glass and does not need to incorporate tempered glass to be deemed as such, according to Schimmelpenningh. The material simply needs to meet the requirements of CPSC 16 CFR 1201 or ANSI Z97.1.
“The building codes reference the performance and not the type of safety glazing except when glass fall-out is a concern. In these cases, they specifically reference laminated safety glazing (skylights, overhead, balcony, etc.),” she says.
Misconception: Hurricane Glass Is Bullet Resistant
Ron Hull, Americas marketing manager for Kuraray America’s PVB division, says he’s had to correct people on the differences between hurricane-rated and bullet-
“This discussion is usually around school security and schools starting to harden buildings,” says Hull.
Schools from Texas to Maine have hurricane-rated glass and as people worry about keeping schools safe from attacks, some think that glass can do the job.
“To be bullet-resistant the glass has to be much thicker, like closer to 1-inch thick, to stop the smallest of bullets,” explains Hull. “People working on schools sometimes even want the whole building to have bullet-resistant glass, which is too expensive.”
Robert Carlson, who works in mechanical engineering at fabricator Tristar Glass in Tulsa, Okla., adds that glass doesn’t need to be bullet-resistant to provide some forced-entry resistance, which can prevent a potential attacker from entering a building until first responders arrive.
Another misconception is that the specification can just include the hurricane glass, rather than an entire system.
“People ask if they can put in hurricane-rated glass, but the whole system has to pass the hurricane rating together, not just the glass,” explains Hull.
Misconception: An IGU’s Outboard Lite Should Be Laminated
Carlson says he sees laminated glass specified as the outboard lite in hybrid insulating glass units (IGU), but there are few situations where that’s needed. Using an IGU with laminated glass provides protection and insulation for energy efficiency.
“In a chemical factory where you’re worried about an explosion from the inside hurting people on the street it makes sense, but the laminated lite should be placed toward the area you’re trying to keep safe,” he explains. “If there’s wind or an explosion on the outside of the building then it will keep the people on the inside of the building safer if the laminated glass is the
Carlson also says that putting the laminated glass as the outboard lite increases the cost of a unit and the challenge of fabricating the unit.
Misconception: Exposed Edges on Laminated Glass Can’t Look Nice
Hull says that many specifiers think exposed edges on laminated glass won’t look neat. While the edges of laminated glass likely won’t look as good as the edge of a monolithic lite, Hull says Kuraray works with many fabricators who can make laminated glass with an attractive edge for frameless applications.
Carlson adds that, depending upon the quality of the fabrication, delamination may only happen on a 1/16- to ¼-inch of the glass around the edge.
“The safety that product provides and the long-term look and durability benefits greatly outweigh any delamination that could occur over time … If a handrail broke a kid won’t fall and that’s more important than the fact that it’s slightly delaminated,” he says.
This article originally appeared as part of the feature titled, “Setting the Record Straight.” To read the full article, which originally appeared in the April 2020 issue of USGlass magazine, click here.
This is an excellent article. I read it when it came out in the April USG issue and have sent it on to three people already. Well done! Thank you!
Watch out for the mfg’s who do post tempering polishing to their tempered lami. This kind of fabrication is not allowed and IMHO is dangerous. Ive heard of a few mfg’s doing this, but can’t confirm it with certainty because they get none of my orders regardless. There are a couple mfg’s that can produce tempered laminated framless glass entrances with no slippage issues so they get all my lami business. If slippage is a concern on tempered lami – deal with the pro’s who do this every day with decorative glass – they know what they are doing.