Corridor Ceiling Rating

[Yankee Chronicler]

In an R-2 building, the corridors are part of the R-2 classification. They are not classified as some other occupancy. However, corridors are regarded as not normally occupied spaces.

IBC section 1020.2 requires exit access corridors in R occupancies to be rated.

1020.2 Construction. Corridors shall be fire-resistance rated
in accordance with Table 1020.2. The corridor walls required
to be fire-resistance rated shall comply with Section 708 for
fire partitions.

Section 1020.2 requires corridors to be rated. It doesn't limit that to corridor walls. I interpret 1020.2 as requiring that the floor-ceiling assembly above a corridor must also be rated -- unless the design spans the corridor with a rated ceiling assembly (such as USG shaftwall installed horizontally) separate from and below the floor assembly above.

As illustrated in the IBC Commentary:

 

[rosegamble]

In an R-2 building, the corridors are part of the R-2 classification. They are not classified as some other occupancy. However, corridors are regarded as not normally occupied spaces.

IBC section 1020.2 requires exit access corridors in R occupancies to be rated.



View attachment 15775

Section 1020.2 requires corridors to be rated. It doesn't limit that to corridor walls. I interpret 1020.2 as requiring that the floor-ceiling assembly above a corridor must also be rated -- unless the design spans the corridor with a rated ceiling assembly (such as USG shaftwall installed horizontally) separate from and below the floor assembly above.

As illustrated in the IBC Commentary:

View attachment 15776

Perhaps, but then does 1020.2 apply to the floor also? That commentary figure addresses one of those very specific detailing "exceptions" but zooming back out to normal fire partition continuity. For the sake of the argument, when a ceiling assembly perpendicular to a fire partition is NOT required to be rated... let's say for example we have multiple two-story residentials unit so the ceiling assembly internal to the unit isn't required to be rated... would you all dispute that the fire partition between the units can simply terminate at the underside of the sheathing (708.4)? It would not require per 704.8 that the ceiling between the floors of the 2 story units be rated.

 

[Yankee Chronicler]

Now you are conflating corridor ratings with dwelling unit separations.

 

[rosegamble]

No,

Now you are conflating corridor ratings with dwelling unit separations.

View attachment 15780

No, I know they are two different things. I am just ascertaining where 708.4's allowance for fire partitions to stop at the sheathing of non-related floor assemblies DO apply, since most here don't seem to think they can be applied in the corridors in question. There aren't that many types of fire partitions so looking for a scenario where this allowance CAN work.