06/04/2026
Most people think both glass panes in an SSG system are structurally bonded to the frame.
They’re not.
Only the inner lite is connected to the frame through structural silicone.
The outer lite? It never touches it.
So how is it held in place?
Through the IGU secondary seal.
That edge seal isn’t just for keeping argon in or moisture out.
It’s part of the load path.
Wind hits the outer lite → transfers through the secondary seal → into the inner lite → then into the structural silicone → finally into the frame.
That changes everything.
What this means in real projects:
• Secondary sealant selection becomes critical
• Edge deletion must be done properly for real bonding
• IGU failure is no longer just visual — it becomes structural
Two panes. Two different roles. One system you can’t afford to misunderstand.