Fire Safety Furthermore, NFPA 101, 2018 clause 8.3.5.4.1 mentions that the Voids created between the fire-resistance–rated floor assembly and the exterior curtain wall shall be protected with a perimeter joint system that is designed and tested in accordance with ASTM E2307, Standard Test Method for Determining Fire Resistance of Perimeter Fire Barriers Using Intermediate-Scale, Multistory Apparatus. Similarly, IBC 2015, Section 715.4 states that the void created between the slab edge and the curtain wall must be sealed with an approved system tested per ASTM E2307 that remains securely in place for the time period equal to the fire-resistance rating of the floor assembly. In general, any void between the fire-rated floor and an exterior wall must be protected using a perimeter fire containment system that has been tested in accordance with ASTM E 2307 - ‘Standard Test Method for Determining Fire Resistance of Perimeter Fire Barriers Using Intermediate-Scale, Multistory Test Apparatus (ISMA). And for evaluating the air leakage (smoke rating) of perimeter joints, ‘UL 2079 - Tests for Fire Resistance of Building Joint systems’ is referred to. Tested Systems, Ratings and Engineering Judgements (EJ’s) The basic configuration of the test furnace and test sample in ASTM E 2307 includes a two-story building with the ground floor fully engaged in a post-flashover fire condition. The fire is provided using two burners, one internal burner placed inside the structure and one external burner placed outside the structure, providing a flame plume up along the side of the building. An exterior curtain wall is then installed on one side of the structure. The void between the curtain wall and the edge of the floor slab is then protected with materials that are intended to prevent the passage of flames through the void and based on the testing the ‘F-Rating (Fire Rating)’ and ‘T-Rating (Insulation rating)’ for the assembly is established.
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To be considered a dynamic perimeter joint protection, both expansion/ contraction and shear movements must be cyclic tested. The cyclic movement demonstrates the perimeter joint protection’s ability to move in expansion/contraction responding to environmental forces (wind, thermal, and seismic) and how they move in shear in reacting to live loads while maintaining a seal between the floor assembly and exterior wall assembly and resisting fatigue and degradation. The cyclic rate, magnitude, and duration of movement can also affect the performance of the perimeter joint protection when subjected to standardised fire exposure and ASTM E2307 provides test conditions for these variables. When field conditions differ from the original design (Eg.: variation in gap width, arrangement of Spandrel assembly, etc.) or unanticipated construction hindrances are encountered, Engineering Judgments (EJ’s) are typically made that recommend alternative methods to ensure the performance of the firestop system is not compromised. Generally, these conditions or hindrances cannot be effectively redesigned so alternative recommendations are to be provided based upon identical designs as that which were fire tested, it is important that they be developed using sound engineering principles and has to be provided by the trained and qualified personnel based on the recommendations prescribed in IFC guidelines. Tested System Design In order to choose a right system, it is important to know the basic details of the application such as the makeup of the exterior wall - Spandrel Glass, Aluminum Panel etc., hourly rating, joint width, static or Dynamic joint etc. The right system selection for a perimeter firestop system can be done by accessing third-party certification
laboratory listing directories. The UL and Intertek listings represent an enormous amount of successful fire containment understanding. The UL & Intertek directory follows a specific nomenclature to identify the different firestop systems listed based on which right system can be chosen to suit the specific needs of the project. For example, UL certifications for Perimeter joints use a unique numbering system. The systems are identified in this category by an alpha-alphanumeric identification system. The first two alpha characters, CW, identify the perimeter-firecontainment system as being for use at the interface of a fire-rated floor and a non-fire-rated exterior curtain wall. The third alpha character is either S or D. The S signifies perimeter-firecontainment systems that do not have movement capabilities (i.e., Static). The D signifies fire-containment systems that do have movement capabilities (i.e., Dynamic). The numeric component uses sequential numbers to identify the maximum clearance distance between the curtain wall and the perimeter of the floor. The significance of the number used is:
No. Range
Max Clearance Distance Between Curtain Wall & Perimeter of Floor
0000-0999
Less than or equal to 2 in.
1000-1999
Greater than 2 in. and less than or equal to 6 in.
2000-2999
Greater than 6 in. and less than or equal to 12 in.
To choose a system, we need to know the basic details of the application. •
The makeup of the exterior wall - Concrete panel, Spandrel Glass, Aluminum Panel, etc.
