UL has just announced a new numbering system for firestop systems and fire-resistive joint systems.

Two tested and listed system categories are moving from a 4-digit System Number to a 5-digit System Number soon (Ex: C-AJ-20000, after C-AJ-2999). Moving forward, when a 4-digit UL numbering series runs out of system numbers, UL will expand the series to a 5-digit numbering system, while existing systems numbers do not change.

Resources are posted on FCIA’s Technical Resource Page and UL’s Resources Page.