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UL Announces Revisions to the ANSI/UL 1479 Firestop System Standard

The ANSI/UL 1479 Fire Tests of Through-Penetration Firestops Standard referenced in Section 712 of the International Building Code and Section R317 of the International Residential Code has been revised to incorporate a change in the construction of samples used to evaluate firestop systems which previously required the use of a chase wall. The systems involved affect penetrations through concrete floor/ceiling assemblies and wood framed floor/ceiling assemblies where the penetrating item is contained within the cavity of a fire-resistance-rated wall assembly.

Prior to the revision, the test assembly would have been constructed with the through-penetrant in the cavity of a fire-resistance-rated wall assembly located beneath the floor/ceiling assembly. The penetrant was protected by the wall in which it was encapsulated. The standards revision eliminates the chase wall and requires that the penetrant be exposed to the fire during the test. This revision reflects a more realistic worst-case condition.

This standards revision may impact the F, T and L ratings of currently certified firestop systems that require the penetrating item be enclosed within a chase wall. After September 20, 2007, all firestop systems published in the UL Online Certifications Directory will reflect ratings achieved using the new test criteria. The new ratings will also be reflected in the 2008 UL Fire Resistance Directory.

What is the impact of this change on designers and code enforcers? In the foreseeable future the impact is minimal since U.S. model building codes reference previous versions of ANSI/UL 1479. The new requirements are more stringent which means that the newly tested systems and previously certified systems should comply with the existing building code requirements. Plan reviewers and designers may notice that systems they previously used for a given hourly rating no longer appear in UL certifications. The absence of a previously existing system utilizing a chase wall indicates that the system did not comply with the new requirements and was removed from the directory/database. There may also be systems where the T rating has been reduced as a result of this change.

Firestop systems may be accessed on the UL Online Certifications Directory, selecting Fire Resistive Assemblies and Systems under Specific Searches. For more information contact UL's Architectural Services Group at (847) 272-8800, Extension 40057 or at NBK.Architectural.Services@us.ul.com.

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