UL Solutions Updates Firestop System Numbering Scheme

UL Solutions, a leading global safety science company, recently announced an update to the numbering scheme for firestop joints and penetrations. This numbering convention provides users with a deeper understanding of the system type by breaking down the elements of the system based upon the construction specifications and model code. UL Solutions categories for Through-Penetration Firestop Systems (XHEZ) and Joint Systems (XHBN) have existed for many years. These categories are nearing the end of the available system numbers. 

Specifically, the C-AJ-2000 series of through-penetration firestop systems and the HW-D-0000 series of joint systems are affected by limitations of the current numbering system. Each series has up to 999 available system numbers: C-AJ-2001 through C-AJ-2999 and HW-D-0001 through HW-D-0999. In an effort to maintain continuity in numbering schemes, and to enable future growth, UL Solutions needs to modify the numbering approach. 

Question: Will UL Solutions change or modify existing system numbers? 
Answer: No, existing system numbers will not change. 

Question: What happens when the HW-D-0000 series reaches its limit once system HW-D-0999 is promulgated? 
Answer: After HW-D-0999 is issued, the next system number that UL Solutions will issue will feature five digits, instead of four. The next system number will begin with 0 (zero), followed by four digits. The 0 (zero) at the beginning of the number series indicates a dynamic head-of-wall system with a nominal joint width of less than or equal to 2 in., and this will remain the same for the new numbering sequence as well. Subsequent system numbers will be HW-D-01001, HW-D-01002, HW-D-01003, etc. 

The leading digit in the numbering sequence and its significance for the type of penetrant, size of joint, etc., in each category will not change. 

The above documents are available as complimentary summaries of all UL Solutions firestop system nomenclature. Visit the UL Solutions Code Authorities website at https://code-authorities.ul.com/uls-numbering-systems-for-penetration-firestop-systems-and-joint-systems/.  

For more information related to product or system listing (certification) from UL Solutions, please contact ULRegulatoryServices@ul.com.