Fire rated glass and framing technology today has come a very long way, and there are systems that can meet the design and code requirements of the application so architects and building owners would not have to overlook or make sacrifices in either design or performance.
The GPX framing supplied here is not a traditional aluminum system. It is a listed and labeled fire resistive, temperature rise system with aluminum cladding. So it may resemble the look of aluminum (which was a design requirement), but unlike traditional aluminum frames, it will not melt or warp under severe fire conditions up to 2 hours.
Concern for moisture control is legitimate, especially since these rated windows are in the exterior of the building. This is why additional independent testing was performed on the SuperLite II-XL/GPX system for air and water infiltration: ASTM E 283-04, ASTM E 547 and ASTM E 331. The SuperLite II-XL/GPX system was unitized in our facility, delivered to the site and installed just like the conventional rainscreen system to which it is adjacent. The insulating element in our framing is designed for exterior applications and is treated for exposure to water.
An expanded version of this story can be found at http://www.safti.com/articles/Fire-rated%20glass%20reaches%20new%20heights.pdf