New revisions to UL Design No. D982 will allow fire protection costs to be cut nearly in half compared with old unrestrained applications. While UL D982 originally only applied to composite construction with normal-weight concrete, these limitations have been discarded as a result of testing that UL performed for AISI and AISC. For background on what necessitated the testing, see “Restrained or Unrestrained?” and “UL Design Considerations” at
UL D982 used to refer only to unrestrained ratings and left it up to the designer to know that it could also be used for restrained conditions. Now it explicitly states that it is useful for both 2-hour restrained and 2-hour unrestrained assemblies. In addition, it:
- Covers both composite and non-composite designs.
- Allows for the use of either normal-weight concrete or light-weight concrete.
- Allows for any welded wire fabric placement location in the concrete slab.
- Applies to metal deck thicknesses from 1 1/2 in. to 3 in., inclusive.
Also worth noting, but not new, is that UL Design No. D982 is not load restricted (see “UL Design Considerations” and “Proper Application of Steel Beam Load Restriction Factors to UL Designs” at
www.aisc.org/ULclarity for further information).
These changes mean UL D982 now covers all common steel-framed floor configurations, and provides two-hour assembly ratings with unprotected steel deck and spray-applied fire protective materials (SFRM) on the steel beam with thickness sufficient to obtain a one-hour unrestrained beam (temperature-based) rating. The design can be used in both the United States and Canada, it works with a wide range of steel deck products and it is valid for any SFRM material bearing the UL Classification Mark. See the
full text of the updated UL Design No. D982 at
Our conclusions from 2013 ring all the more true today. These test results and the expansion of UL D982 they allow are great. They provide a solution that eliminates all need to argue about what fire protection thickness is required. In all common cases, UL D982 allows you to have the same fire protection thickness whether you choose a restrained rating or an unrestrained rating.