Revision to Joint Firestop Testing Standard

To address conditions where no material exist in the joint or where the firestop is not flush with the drywall, UL along with the UL STP 1479 (Standards Technical Panel) approved a revision to allow the required 2-inch TC (thermocouple) pad to be modified. Prior to the revision, the standard UL 2079 did not permit the modification of the thermocouple pad for joint widths that are less than 2 inches. This could result in the TC floating in the gap potentially creating a less severe condition. This may prove problematic specifically for metal track systems that include strips of firestop on the track, versus traditional sealants or sprays, since the existing required 2-inch pad will not fit in the joint space without modification.

UL 2079 5th edition was revised to allow modification to the pad such that it still meets the intent of providing insulation around the TC while continuing to have the wire leads immersed a minimum of 1 inch, along with matching the maximum width of the joint. This will help to ensure that proper fit and coverage is maintained over the thermocouple on joints smaller than 2 inches.

This standards revision may impact the Assembly Rating of existing certified firestop systems that have a recessed joint of less than 2 inches. All firestop systems published in the UL Online Certifications Directory should now reflect ratings achieved using the new test criteria.

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 or now require additional material to pass the rating criteria. The absence of a previously listed systems could indicate that the system did not comply with the new requirements and was removed from the directory/database. Previous systems that have been re-tested to UL 2079 5th edition should be reviewed for any changes that may include additional means and methods of construction to obtain an approved system.

For the most up-to-date listings, reference the UL Online Certifications Directory.