Appeal 24683

OSSC 706 – Fire Walls (NFPA 221 Chapter 6 – Fire Walls)

ORIGINAL TEXT:
OSSC 706.2 – Structural Stability: “Fire walls shall be designed and constructed to allow collapse of the structure on either side without collapse of the wall under fire conditions. Fire walls designed and constructed in accordance with NFPA 221 shall be deemed to comply with this section.”
NFPA 221 6.10.3 – Double Fire Walls: “Openings in double fire walls shall be protected using one fire door in each separate wall.”

RECONSIDERATION TEXT:
Reconsideration of Appeal 24522, Item #1, to clarify fire wall construction.

ORIGINAL TEXT:
We request the use of single protected openings in a double fire wall.

RECONSIDERATION TEXT:
We seek to confirm approval for the attached fire wall assembly as confirming to the original condition of appeal decision for both firewalls to be 3-hour rated for their full height.

ORIGINAL TEXT:
We are proposing a new mixed-use multi-family structure (primarily R-2 occupancy). Our building design features a double fire wall separating two distinct buildings for purposes of determining number of stories. One side is comprised of a concrete podium style building with four stories of Type VA building over two stories of Type IA building in accordance with OSSC 510.2. The other side is comprised of four stories of Type VA with a basement. Though each side of the fire wall contains only four stories of Type VA, only two of the stories overlap and, without the fire wall, the single building could be considered six stories and, thus, not allowed. The fire wall is otherwise not required for purposes of determining building area or exit travel distances.
In the corridors for the four floors and basement that the two buildings share in common, we are proposing a fire rated door assembly in only the fire wall of the larger, podium style building. There is also a larger fire shutter in the wall at the lobby. The fire rated doors and shutter will be interconnected to the fire alarm to automatically shut upon activation of the alarm.
The fire wall construction on the podium side (below the podium) will be 3-hour rated concrete construction and the fire wall construction for the Type VA buildings on either side will be 2-hour rated wood frame construction. The fire rated doors and shutter will have the required rating for the fire wall with the highest rating on each story. There will be no structural connections between the two walls and collapse of one side would not impact the other. All other Code requirements of OSSC 706 would be satisfied.
The entire structure will be equipped throughout with NFPA 13 sprinkler system per OSSC 903.3.1.1.
Alternatively, the wall may be classified as a Fire Barrier if the proposed number of stories of Type VA construction is approved. The construction of the wall as described above would not change as the double wall also serves as a seismic joint.

RECONSIDERATION TEXT:
The attached schematic wall section of the fire wall condition shows each wall of the double fire wall to be 3-hour rated for the full height. For the Type IA construction, this is achieved with cast-in-place concrete walls. For the Type VA construction, this is achieved with Albi DriClad panels and is supported via the EJ letter from Code Unlimited. The attached email chain confirms that 3-hour wood framed walls for the Type VA portion would be accepted. The other conditions of approval (3-hour fire rated doors and additional sprinkler heads) will be provided.

ORIGINAL TEXT:
The site is split zoned with differing height and setback requirements on each side of the zone line and the proposed building design is a direct response to those constraints while still providing an adequate return on investment to make the project feasible. Construction of a protected opening in both walls of a double fire wall poses a challenge for egress through the openings due to the required separation of doors in a series. Furthermore, as the primary reasons for creating a fire wall with horizontal exits do not exist (subdividing for allowable area purposes or reducing exit access travel distance), the relative necessity for a door in each wall is lessened.

RECONSIDERATION TEXT:
We request that the proposed wood framed 3-hour wall assembly be approved. Providing non-combustible materials for fire wall construction would pose constructability challenges with the interface to the balance of the wood framed structure.