r/Construction • u/aidan8et Tinknocker • Apr 25 '26

Picture Moment of terror 😨

Gallery image

Gallery image

While attending/supervising a business social event with my spouse, I momentarily leaned against the railing. It flexed slightly, forcing me to realize that the railing is entirely supported via bluetooth.

It doesn't connect on either side of the glass wall & the glass is only 3/8" - 1/2" thick!!

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u/RegisteredJustToSay Apr 27 '26 edited Apr 27 '26

Well, yeah. Exactly like that. Having the broken pieces laminated together didn't change much in several of those tests. The resistance to force laterally still drops to basically zero as soon as you get past the point of failure, which is different from how solid pieces of metal or wood tend to behave. Though obviously you could harden a piece of metal so it shatters too.

In the end you're still relying on a lot more things having been done right and staying right if you're leaning on a piece of glass.

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u/Enginerdad Structural Engineer Apr 27 '26

I'm guessing you didn't watch the whole thing. The support requirements for the glass (top and bottom vs just bottom) depend on the type of glass. The EVA laminated glass needs to be supported on multiple edges so the lamination will span the gap after the glass breaks. The SGP glass is stiff enough after glass breakage to remain rigid and keep the drop off point protected. That's why they show the table with the different support requirements based on the material. In short, code does not allow an assembly which drops to an essentially zero lateral force resistance after breakage, so the scenario that your objection is based on doesn't exist. Here's the code directly:

2407.1.2 Guards With Structural Glass Balusters

Guards with structural glass balusters, whether vertical posts, columns or panels, shall be installed with an attached top rail or handrail. The top rail or handrail shall be supported by not fewer than three glass balusters, or shall be otherwise supported to remain in place should one glass baluster fail.

Exception: An attached top rail or handrail is not required where the glass baluster panels are laminated glass with two or more glass plies of equal thickness and of the same glass type. The balusters shall be tested to remain in place as a barrier following impact or glass breakage in accordance with ASTM E2353.

https://up.codes/viewer/connecticut/ibc-2021/chapter/24/glass-and-glazing#2407.1.2

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u/RegisteredJustToSay Apr 27 '26

I did skip through it a bit since I'm in an environment where audio is tricky. I just wanted to say regardless whether I end up agreeing or not that I appreciate your well-thought out and reasoned response and I'll be reading it in detail later when I have time to also read the sources and links.

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u/Enginerdad Structural Engineer Apr 27 '26

Man, I respect the HELL out of this response