Managing Director @ Skyline Windows + Schüco | All Things Facades Podcast
Sloped glazing can be tricky, particularly when factoring in the load path of a heavy insulated glass unit assembly. Typically, the deadload weight is carried on the glass chairs, and transferred back to the structure via framing members. The lateral loads are accounted for via mechanical retention (pressure plates) or a silicone bead. That’s when you are designing for a vertical facade (picture a flat wall). But what happens when you start shifting the plane as shown below?
I’ll take the bait 🎣… Pending to confirm with the players below, but: can you consider both the IG Unit sealant and the weather seal silicone as also providing deadload support to that outer monolithic glass lite? One could work in shear and the other could deadload glass to glass with the weather seal working as an in-place gasket. You would need confirmation/acceptance from: - IG manufacturer - Sealant manufacturers of both IG sealant and outer weather seal - Your Glazing Engineer of Record
Luis De fex Lora
2mo
I believe that in that detail exist kind of setting chair, also that is a ssg facade, is posible that the sealant bite was calculated to this specific condition. Also we do not know the real resistance of the isolator element that could be made in a solid pvc or a material with a good mechanical properties. My final and point of view we are so lucky that the sealant suppliers use a really high security factor in their bites designs and the structural sealant end up as a unknown hero.
Mohd H. Murad
2mo
When shifting the plane of a sloped glazing system, the load path must be re-evaluated. The deadload might still rely on glass chairs, but the distribution changes, affecting the framing members. Lateral loads also need reconsideration, as mechanical retention or silicone beads may behave differently. Careful analysis and potentially different support strategies are necessary to ensure stability and performance.
This system includes dead load support elements for the IGU. In contrast to the vertical façade, when calculating of IGU and structural silicone joint, it is necessary to take into account, in addition to wind load, possible service and snow loads. And of course, the angle of inclination should not be less than 7° from the horizontal (at least for Europe). The only weak element here can be the gaskets of the mullions and transoms. For them, there will be a significant additional load. With the right calculations, it works great.
Paul Singley
1w
This detail doesn’t look like a sloped system. But, in the case of a sloped system, dead loads won’t change. Wind loads will lessen as you tilt. But, conventional wisdom says, engineer the wind load as if it were flat. And by the way, no sealant company will warranty anything less than 1/4”.
At least 3 other severe mistakes in this drawing... Even for a vertical facade I wouldn't consider this system.
Ted Baumgardner
2mo
Doesn’t that make it easier to transfer the deadload back to the mullion?
Ethan Yun
2mo
1. Increase the Size of the Cruciform Support 2. Add Additional Supports 3. Use Thicker or Stronger Glass 4. Modify Installation Method 5. Consult a Structural Engineer 6. Redesign the Glass Panels 7. Implement Load Distribution Mechanisms
Note that the exterior sealant is destined to fail over time, and this design does not comprise any drainage solution as water will infiltrate. We did some lab test on drainage in sloped curtain wall systems. For sure, this NOT the way to go.
Manager Southwest Region & Building Envelope Consultant at Heitmann & Associates, Inc.
2moI need to disagree! I don’t believe this is a sloped glazed system. Perhaps a vertical glazing system shown in a sloped glazed application? Slope glazing systems have rafters and perlins with weep troughs to manage condensation. As for the SSG application.. the glass is structurally attached to interior frame channel which is shown to be interlocked to the rafter/mullion beyond the injection molded clip. This problematic detail is not a desirable slope glazing system application.