UL Solutions, a leading global safety science company, recently announced an update to the numbering scheme for fire resistance rated assemblies. This numbering convention provides users with a deeper understanding of the assembly type based upon the construction specifications and model code.
The series of fire resistance rated wall assemblies that include metal studs, gypsum board, lath and/or plaster within the tested design (U400, V400, and W400) have reached the end of the available design numbers. To maintain continuity in numbering schemes, and to enable future growth, UL Solutions must modify the numbering approach. As a result, all future metal stud, gypsum board, lath and/or plaster wall assemblies will be categorized under a newly created U4100 series. For example, the first few design numbers in this series will be U4101, U4102 and U4103.
The leading letter in the series (U) still refers to a wall and partition assembly. The leading digit in the series (4) still refers to metal stud, gypsum board, lath and/or plaster. Refer to the numbering system table in the BXUV Guide for further information.
Frequently Asked Questions
- Will UL Solutions change or modify existing design numbers for metal stud wall assemblies?
No, existing design numbers will not change.