UL Detail Does Not Exist

[radioatlas]

Hi, not sure if I'm posting in the correct category...

We need to show a 1HR fire partition between sleeping units in an existing historic motel building. The existing bearing wall assembly is a double-wythe 4" CMU cavity wall. UL has verified in writing that they don't have a tested assembly for this case, how do we show our existing condition meets the 1HR rating?

R-1 Occupancy, Type II-B, non-sprinklered.

 

[RLGA]

Use the calculated method per Section 721.3 (2009 IBC and earlier) or Section 722.3 (2012 IBC and later).

You need to know the equivalent thickness of the masonry units and the aggregate type. Even using the aggregate that provides the least fire resistance will still get you to a 1-hour rating.

 

[radioatlas]

Thanks, @RLGA ... That's very helpful. Rookie over here has always been able to find UL details up until now.

 

[mtlogcabin]

Since it is Historic the IEBC might be an easier source to use

2012 IEBC Resource A Guidelines On Fireratings of Archaic Materials and Assemblies and the appendix is another source

INTRODUCTION

The fire resistance tables that follow are a part of Resource A and provide a tabular form of assigning fire resistance ratings to various archaic building elements and assemblies.

These tables for archaic materials and assemblies do for archaic materials what Tables 720.1(1), 720.1(2) and 720.1(3) of the International Building Code® do for more modern building elements and assemblies. The fire resistance tables of Resource A should be used as described in the “Purpose and Procedure” that follows the table of contents for these tables.

 

[RLGA]

Thanks, @RLGA ... That's very helpful. Rookie over here has always been able to find UL details up until now.

You're welcome. UL is great for finding different types of fire-resistive assemblies, except for masonry assemblies. They have some masonry assemblies, but they require UL-labeled CMUs and there are roughly 28 companies across the U.S. that have UL-labeled block. The manufacture of CMU is highly regionalized, so there are many areas that are not served by UL-labeled CMU manufacturers. Thus, the best solution is to use the calculated method.

Since it is Historic the IEBC might be an easier source to use

2012 IEBC Resource A Guidelines On Fireratings of Archaic Materials and Assemblies and the appendix is another source

INTRODUCTION

The fire resistance tables that follow are a part of Resource A and provide a tabular form of assigning fire resistance ratings to various archaic building elements and assemblies.

These tables for archaic materials and assemblies do for archaic materials what Tables 720.1(1), 720.1(2) and 720.1(3) of the International Building Code® do for more modern building elements and assemblies. The fire resistance tables of Resource A should be used as described in the “Purpose and Procedure” that follows the table of contents for these tables.

Resource A does provide for multi-wythe walls, but you have to make sure that the notes specifically say that. For Table 1.1.4 (8" to less than 10" thick), there is no assembly for a double-wythe 4-inch CMU. I doubt you could add the ratings for two 4-inch CMU wythes per Table 1.1.2 (4" to less than 6" thick) to determine the overall rating of the wall assembly. I have no doubt that the wall described is at least 1-hour rated (if not higher) and the rating of the wall could probably be based on just a single-wythe assembly per Item Code W-4-M-87, but if someone needed a 2-hour assembly using the same double-wythe wall, Resource A of the IEBC won't help much.

 

[jar546]

Use the calculated method per Section 721.3 (2009 IBC and earlier) or Section 722.3 (2012 IBC and later).

You need to know the equivalent thickness of the masonry units and the aggregate type. Even using the aggregate that provides the least fire resistance will still get you to a 1-hour rating.

Chapter 7 can really be your friend sometimes.

 

[mp25]

ACI 216.1 will be the one of the best sources for info in this case.