Division 7 Ebook Page 86 Enclosure Solutions FAQ

ENCLOSURE SOLUTIONS FAQs 7 25. If I have a steel back pan on the back of my spandrel (back pan inboard of the curtain wall insulation), does the steel back pan act as the backer-reinforcement member to keep the compression requirement and tight seal of the Safing Insulation within the void to prevent the interior spread of flame and hot gases? A: The issue with a steel back pan is that steel expands when exposed to heat. When the steel back pan expands, it warps or oil cans. Unfortunately, the Safing Insulation cannot form to the various curves and shapes from the oil canning. Without a tight seal where the Safing Insulation is in contact with the interior face of the back pan, fire breaches to the floor above. All tested steel back pan systems listed in the Underwriters Laboratories Fire Resistance Directory require a backer reinforcement member and other design criteria such as increased mechanical attachment of the curtain wall insulation and a Safing shelf installed below the Safing to provide additional protection to the seam between the interior face of the back pan and where the Safing Insulation is in contact with the back pan. For more details refer to the listed and approved systems within the UL Fire Resistance Directory. 26. In a Perimeter Fire Containment System, what is the difference between an F rating and an Integrity rating? A: An F-Rating is required by the codes for providing a barrier against the interior spread (through the safe-off area) of flame and hot gases. F Rating is also a requirement of ASTM E 2307 (Standard Test Method for Evaluating Perimeter Fire Barrier Systems Using the Intermediate-Scale Multi-Story Test Apparatus). The F Rating is the ability of the design to prevent flame and hot gasses from passing through the interior of the system between the edge of the slab and interior face of the curtain wall. Integrity Rating, on the other hand, is a rating provided only by UL. This rating represents the system's ability to maintain the interior joint (F-Rating) plus prevent the leap frog effect from causing failure for the hourly Integrity Rating listed. Leap Frog is where the fire breaks the glass on the room of origin and the flame and hot gasses escape outside the building and up the face of the curtain wall then breaks through and re-enters the building by means of the vision glass on the floor above. Although not a requirement of the building codes, this is still a critical area that needs to be considered for providing the maximum protection and fully containing the fire to the room of origin to allow the occupants the time needed to safely exit the building and first responders a safe entry time into the building to extinguish the fire. 28. There is an exception in the current IBC Section 715.4 building codes where it states: "voids created at the intersection of the exterior curtain wall assemblies and such floor assemblies where the vision glass extends to the finished floor level shall be permitted to be sealed with an approved material to prevent the interior spread of fire. Such material shall be securely installed and capable of preventing the passage of flame and hot gases sufficient to ignite cotton waste where subjected to ASTM E 119 time-temperature fire conditions...for the time period equal to the fire-resistance rating of the floor assembly". Are there approved materials tested to ASTM E 119 that will provide the protection if this exception exists on the project? A: It is Thermafiber's opinion that this language was added to the code for two reasons. 1. There were no tested designs at the time that allowed for the extension of vision glass down to the floor line. 2. This exemption also allowed for systems tested prior to the development of the ASTM E 2307 to be grandfathered and covered under the new code language. However, in regards to reason 1, we now have tested and listed assemblies that allow for the vision glass to be extended down to a point where it is level with the top surface of the floor slab. One such system is CW-D-1014 which has an F rating of 2 hours per ASTM E 2307. Therefore, it is our recommendation to always go with a tested and proven system, compliant with ASTM E 2307 for providing the maximum level of fire containment at the perimeter of the building. Therefore, there should be no reason for someone having to provide proof that the material is sufficient per the ASTM E119 exception.

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