R2 Exit Access Stair Vs Interior Exit Stairway

[KHL]

2018 IBC. R2 occupancy. VB. 2-story. Fully sprinkled, nfpa 13
This is basically 8 apartments with on center interior corridor leading to an enclosed stairway on each end of the corridor which then exits to the exterior. Pretty straight forward.

Question is if the stairs would be required to be rated?


1019.3 below would say that the stairs are NOT required to be rated because they are only connecting two stories:
1019.3 Occupancies other than Groups I-2 and I-3.
In other than Group I-2 and I-3 occupancies, floor openings containing exit access stairways or ramps that do not comply with one of the conditions listed in this section shall be enclosed with a shaft enclosure constructed in accordance with Section 713.
1.Exit access stairways and ramps that serve or atmospherically communicate between only two stories. Such interconnected stories shall not be open to other stories.

BUT, per 1020.6 below, and my general intuition, the stairs should have the same rating as the 2nd story corridor (which is 1/2 hr per table 1020.1):
1020.6 Corridor continuity.
Fire-resistance-rated corridors shall be continuous from the point of entry to an exit, and shall not be interrupted by intervening rooms. Where the path of egress travel within a fire-resistance-rated corridor to the exit includes travel along unenclosed exit access stairways or ramps, the fire-resistance rating shall be continuous for the length of the stairway or ramp and for the length of the connecting corridor on the adjacent floor leading to the exit.

I'm really over thinking this - sigh.

 

[JMarsh]

I'm not sure Multi-Family R2 can be considered "VB" due to Section 420?

 

[KHL]

I'm not sure Multi-Family R2 can be considered "VB" due to Section 420

I don't see in 420 anything that would eliminate VB as an option? Is there a specific part of 420 that you see that indicates no VB?
VB is allowed with R2 in all of chapter 5 as far as area/height/stories

 

[Jay Smith]

Regarding your intuition point - The exit access stair does have the same level of protection as the corridor in that it is separated from the apartments by fire partitions.

 

[KHL]

Regarding your intuition point - The exit access stair does have the same level of protection as the corridor in that it is separated from the apartments by fire partitions.

yes, good point

 

[KHL]

yes, good point

However, if the rating was required by 1020.6 (continuing corridor rating from corridor through stairs) - then that will also require compliance with 1023.7 also, meaning rated exterior walls. If they are not required to be rated, then no rated exterior walls.

In this situation, the exterior walls of the building are not required by section 705 to be rated - so if the stair is required to be rated- then our exterior walls of the stair, plus 10 ft horizontally will need to be too.

1023.7Interior exit stairway and ramp exterior walls.
Exterior walls of the interior exit stairway or ramp shall comply with the requirements of Section 705 for exterior walls. Where nonrated walls or unprotected openings enclose the exterior of the stairway or ramps and the walls or openings are exposed by other parts of the building at an angle of less than 180 degrees (3.14 rad), the building exterior walls within 10 feet (3048 mm) horizontally of a nonrated wall or unprotected opening shall have a fire-resistance rating of not less than 1 hour. Openings within such exterior walls shall be protected by opening protectives having a fire protection rating of not less than 3/4 hour. This construction shall extend vertically from the ground to a point 10 feet (3048 mm) above the topmost landing of the stairway or ramp, or to the roof line, whichever is lower.

 

[Jay Smith]

However, if the rating was required by 1020.6 (continuing corridor rating from corridor through stairs) - then that will also require compliance with 1023.7 also, meaning rated exterior walls. If they are not required to be rated, then no rated exterior walls.

In this situation, the exterior walls of the building are not required by section 705 to be rated - so if the stair is required to be rated- then our exterior walls of the stair, plus 10 ft horizontally will need to be too.

1023.7Interior exit stairway and ramp exterior walls.
Exterior walls of the interior exit stairway or ramp shall comply with the requirements of Section 705 for exterior walls. Where nonrated walls or unprotected openings enclose the exterior of the stairway or ramps and the walls or openings are exposed by other parts of the building at an angle of less than 180 degrees (3.14 rad), the building exterior walls within 10 feet (3048 mm) horizontally of a nonrated wall or unprotected opening shall have a fire-resistance rating of not less than 1 hour. Openings within such exterior walls shall be protected by opening protectives having a fire protection rating of not less than 3/4 hour. This construction shall extend vertically from the ground to a point 10 feet (3048 mm) above the topmost landing of the stairway or ramp, or to the roof line, whichever is lower.

Based on 712.1, I’d say an enclosed vertical opening requires a shaft enclosure per 712.1.1, even if the function in the enclosure is a stair that could have been unenclosed.

 

[KHL]

Based on 712.1, I’d say an enclosed vertical opening requires a shaft enclosure per 712.1.1, even if the function in the enclosure is a stair that could have been unenclosed.

Yes, I see, 712.1.1 says comply with 713.
713.1 says interior exit stairways shall comply with 1023.
1023.2 says - 1 hr rating if less than 4 stories

I think I just need to go with that