Rated wall exposure

[Sifu]

I have a IIIB, mixed use R2 and S2 (parking garage) building with a 9' FSD. I want to make sure my thinking is correct:

A IIIB building requires a 2-hr exterior wall (bearing) per IBC t601. It also requires a 1-hr rated wall if the FSD is 5' to 10' per t602. So the assembly would be for a 2-hr rated interior exposure and a 1-hr rated exterior exposure. Have I missed anything?

 

[RLGA]

It would have to be a 2-hour exposure for both interior and exterior per Section 705.5 (2018 IBC) since the fire separation distance is less than 10 feet. You have to use the most restrictive fire rating for the entire wall assembly.

 

[Sifu]

It would have to be a 2-hour exposure for both interior and exterior per Section 705.5 (2018 IBC) since the fire separation distance is less than 10 feet. You have to use the most restrictive fire rating for the entire wall assembly.

That was my first comment, but in looking for a code to cite I couldn't find one. I also am having trouble finding any 2-hr interior/exterior exposure wall assemblies.

 

[classicT]

That was my first comment, but in looking for a code to cite I couldn't find one. I also am having trouble finding any 2-hr interior/exterior exposure wall assemblies.

Check out footnote 'e' of Table 601 and footnote 'a' of Table 602.

 

[RLGA]

That was my first comment, but in looking for a code to cite I couldn't find one. I also am having trouble finding any 2-hr interior/exterior exposure wall assemblies.

Many 2-hour assemblies allow any Type X gypsum board including exterior gypsum sheathing. Once the basic fire-resistive wall assembly is selected, you can add any exterior wall covering that complies with Chapter 14.

 

[Sifu]

As a side, which may help

Check out footnote 'e' of Table 601 and footnote 'a' of Table 602.

Excellent info, now I have the citation to validate my thinking. As a side: when looking at the UL assemblies, some indicate the exposure as from interior, or exterior, but some don't indicate it at all. General info note #5 says unless otherwise noted all are considered to be interior applications. When I search the directory with the key word "exterior" several assemblies come up with no indication as to exposure side. Is it assumed to be interior only for these assemblies?

 

[classicT]

Typically, when not specified as having an exposure from only exterior or only interior, it is a balanced assembly and is rated for exposure to both faces.

 

[Sifu]

The general notes say that unless specified the wall is limited to interior applications only. So if I have an assembly that does not specify it as an exterior wall, wouldn't it be excluded? What I have is a IIIB building, requiring FRTW framing and plywood for shear, that requires 2-hr ratings on both faces, with stucco and adhered masonry veneer on the exterior.

The DP is unable to provide an assembly and is asking to defer the issue until he can find something. This was the response/proposal (with U371 attached):
OK, we found the attached which doesn’t speak to interior or exterior, but can we use this plus another layer of gyp. outside? Then have this comment as a red line so that we can get an approved set minus this rating? I feel like we can work with our contractor and UL folks after the holiday to get the right assembly. What do you think?