# 1 Hour Rated Exterior Wall



## T-Bird (Oct 3, 2016)

IBC Sec 705.5 The required fire-resistance rating of an exterior wall with a fire separation distance greater than 10 feet shall be rated for exposure from the inside.

Would this indicate the protection at the interior side of the wall is 5/8" type X, and the protection at the exterior side of the wall is omitted?

Can I reference something like UL #U309 as the fire test?

This is a sprinklered building with R-2 occupancy and type V-A construction.
Sprinkler used to increse allowed building height from 3 stories to 4 stories.

Table 601: Type V-A exterior walls= 1 hour rated
Table 602: X>30', all types of construction, R-2 Occupancy= 0


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## T-Bird (Oct 7, 2016)

I've learned that UL tests indicate when the assembly is rated for inside exposure and as a result found UL Test No. U356, and that should work for my project.
Thanks everyone for your help.


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## JBI (Oct 11, 2016)

Table 602 is only used to raise a required rating, never to lower it.
Rated assemblies, generally, are symmetrical (rated from either side).
UL designs, when used, specify the required finishes for both sides of an assembly.


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## BayPointArchitect (Oct 11, 2016)

While I generally agree with JBI, there are exceptions.
My Fire Resistance Design Manual, published by Gypsum Association, very clearly indicates the interior of the building as the "fire side" for a number of 1 hour fire-rated exterior walls.  UL R7406 and UL Design V421 both illustrate a typical metal building wall that has nothing but the metal skin attached to the outside.  1 hour fire-rated protection on the inside only.


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## steveray (Oct 12, 2016)

^^^^^^Agreed, I had this issue with some townhouses that were stepped. Designer didn't want to use densglass on the outside and couldn't find a wall rated from both sides with FRTW on the outside...


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