Sitting through 4½ days of industry trade meetings is not what I would call a vacation, even if the weather in Vegas was ideal. Hotel chairs not being the most comfortable, the joke in the hall on Sunday morning, a little more than halfway through the Glass Association of North America (GANA) Annual Meeting and Building Envelope Contractors (BEC) Conference schedule, was that we were going to see if we could find a sponsor for a Sitz pillow (remember the “doughnut” new mothers take home from the hospital?). We even came up with a name for it, in honor of Greg Carney: “The Glass Hole.” Any takers on the sponsorship for next year?
As always, there was A LOT of ground covered. Just two of the biggest items were:
**Tempered glass handrails are all but gone. In some cases they will be still be permitted, but for the most part, laminated glass is going to take their place. Edge offset tolerances likely will be set by individual fabricators, much like roller distortion. The fabricators who can minimize the offset will tend to have a leg up on the competition. And, edge fabrication is another fabricator-driven issue: how to finish the edge, how will it look compared to tempered glass options (knowing the architects are going to want something to match what they’ve been used to seeing on tempered glass – you know how that goes).
**The GANA Laminating Division will be updating their GIBs to include a post-breakage requirement. The intent is to prevent someone / something from falling through a broken glass lite. If you think about it, that’s almost a necessity. One glazing contractor I talked with mentioned that they’re seeing some of this coming to them for future work. He said caps might play a part in this since caps have to span multiple lites to aid in not only keeping the glass in the opening, but preventing fall through.
My take on this: The typical 200-pound point load/50-pound linear load now in the codes will have a fall-through load, which will have to be verified. The laminated glass has to stay intact and remain in the opening when a load of X pounds breaks the glass, and leans on it, the equivalent of cycling it for the impact testing, similar to the large/small missile impact testing we’re all familiar with for hurricane testing. The big question is, “when?” That’s not known at this point.
Regarding the material used to support the glass in extruded aluminum or metal shoes in exterior handrail application: There’s some question about the gypsum based fill material being compatible with laminated glass, but that doesn’t appear to be a concern. But, its deterioration when exposed to water is another matter. Substitute materials are available, but there’s a concern about epoxy being able to deal with glass and metal expansion/contraction due to thermal loading. Epoxy and polyurethane fillers are out there, but they’re more expensive. One manufacturer has a dry/continuous shim system that may be the way to go with this type of installation. Further development is likely, but make sure whatever you’re doing works long term.
Another big topic was whether ceramic frits weaken glass. This is still early on – there are more unknowns than knowns, at this point, and experts on either side of the issue are weighing in. Some believe that adding ceramic frits is a thermal stress issue, similar to what happens to glass because of edge damage, or heat absorption. Others believe the process of firing the frit onto the glass lessens its capacity to resist wind or other loading that may be placed upon it.
Presently, there’s a DIN/European standard that says ceramic frit weakens glass. The ASTM E1300 “Standard Practice for Determining Load Resistance of Glass in Buildings” is being reviewed to add ceramic frit to the types of glass not included (or covered) by the standard, lumping it in with the likes of wired glass, acid etched or sand blasted glass. However, that change is not likely to pass the balloting process.
Some of the issues appear to be coming from installations in temperate climates, where daily thermal cycles are at their extremes (e.g., the glass is extremely hot during the day, and much colder at night, with that cycle duplicated over several/many days in a row).
Confusing the issue even more is that presently not a lot of testing has been done on new glass, or for that matter, on weathered glass, to see what impact age has, if any. Data that formed the basis of the DIN European standard hasn’t been published. The consultants vary on their positions, and the manufacturers are not commenting yet on whether or not this is a concern. As more info becomes available, that’s likely to change with time.
In my opinion, since most spandrel glass is at least heat strengthened for thermal loading, it may be that these materials will have to be tempered to offer a higher level of resistance. But then the question still is, as mentioned above, if the glass is first tempered before the frit is applied, does the act of heating the glass to fuse the frit to the glass weaken the compressive stresses in the glass used to determine its strength per ASTM E1300? Sounds a bit like chasing your tail, doesn’t it?
This another one of those issues that’s developing, and the verdict’s not anywhere close to being carved in stone. For now, it might be a good idea to ask the fabricator what they know when discussing potential orders and quotes.
Lastly: if you ever have an opportunity to listen to Jim Abbott, don’t pass it up. Jim is the major league pitcher and Olympic gold medalist born without a right hand, who rose well beyond that challenge. I don’t know where to start describing his keynote address. His parents certainly got him pointed in the right direction. And, he clearly took their lessons of perseverance to heart. His courage, determination, accountability, and trusting in himself and others –was inspiring. At the end of his talk, the room jumped to its feet; I was glad to join in.
More later on other topics covered at Annual Conference and BEC.