Today’s post picks up where the one from last week left off, with more of the high points covered at the GANA Fall Conference held in Toronto September 23-25.
Handrails, obviously, are still getting a lot of attention. Being in Toronto, where so much of the news about guardrails is emanating, it seemed only natural to hear how the Canadians are addressing the issue. CSA’s Dwayne Torry, talked about the A500 standard, which is being developed with cross-representation of regulators, suppliers, architects and users (not sure what that means: installers? building owners?). They’re looking to develop a standard to serve as “a consistent baseline for design.” The plan now is for spring 2015 publication. Like the AAMA/WDMA/CSA standards for doors and windows, it might be beneficial for those of us on this side of the border to pay attention.
Also, testing of handrails was discussed, both in the pre- and post-construction phases. Most exterior guardrails use the exterior cladding wind load, either from wind tunnel testing or by code, to determine the design load for the handrails. Further research is required to determine if that’s realistic, but no one has stepped up to do that, yet. Likewise, there is now additional attention being paid to more stringent post-installation maintenance requirements – everything from checking glass fittings to checking the connection of the guard rails to the structure, etc. If you install handrails, this is certainly worthy of consideration.
Not a lot is being talked about the causes of the handrail glass breakage, due in large part to the on-going “who’s to blame” game being played on many projects. It’s not only nickel sulfide, but other causes, such as improper installation (e.g., grommets not installed around bolts passing through the glass, posts not installed vertical or in plane with the glass, etc.). The root causes may not be known for years.
Associated with the handrail discussion were some of the items covered in the GANA Laminating Division meetings. There was some talk about the edges of laminated glass in handrails, and whether they should be finished, pre- or post-laminating. If the architect uses tempered glass, a finished, polished edge is often specified. But, laminated glass complicates that, as most laminators will polish the edges before laminating, and getting the lites in the laminating sandwich to match up is difficult, plus the laminating layer oozes out from between the lites. One possible alternative would be to polish the glass after lamination, but apparently that’s not easily accepted given the budget and schedule constraints of most projects.
One thing I learned about that I didn’t know before: using a cementitious material to set laminated glass into sill shoe isn’t such a good idea. The cement-based material can damage the laminating layer. I know for the next project where this comes up, a discussion will be warranted between suppliers and glass fabricators.
The use of laminated glass in doors, and the effects of clamping hardware and/or patch fittings is still being researched, they’re looking for a door manufacturer to lead the testing.
One issue that’s starting to surface, and it’s really early on, so no immediate cause for alarm, is whether ceramic frit on spandrel glass is causing the glass to loose strength. There’s no data on this, yet, either. What follows is strictly my take on this, not a lot of consensus, and therefore no conclusions were reached. On one hand, some manufacturers talked about applying frits to glass before the glass was heat-strengthened, in which case they report there’s no loss of strength if the glass gets the proper treatment. But, other manufacturers may be applying the frits as a secondary operation after heat treating, and the re-heating may weaken the glass.
What’s confusing this was two of the leading fabricators are on opposite sides of the question. One insisted that there is no evidence that ceramic frits were causing breakage due to wind loading, that ASTM E1300 still worked with no drop in performance for heat-treated, fritted glass. Another said there was. So, we’ll have to wait and see where this goes.
A lot covered. A lot to do. Many of the industry manufacturers are well represented at GANA. We’ll look to cover some of this at BEC in the Technical Committee, especially if it rises to the level that the glazing contractors will start being asked about it going forward.