Egress from one building into and through another

[Orion's Master]

2012 IBC. I am working with a developer in partnership with the City to develop a 4 story mixed use building with residential (R-2) above the egress at grade level. The City operates a 5 story parking garage (S-2) on the adjacent lot. The intent is to use the existing elevator in the parking garage as the accessible means of egress for the upper floors of the R-2. Only one new egress stair is planned connecting all levels to the exterior. The second means of egress at each floor is to be a horizontal exit through the required fire wall assembly into the parking garage adjacent to the garage egress stair. Questions:
1. Can we use a horizontal exit between buildings owned by two separate entities on different lots?
2. If the horizontal exit is allowed is this a violation of 1014.2 since the egress would be from a lower hazard (R-2) into a higher hazard (S-2).
3. To use the elevator of the S-2 parking garage it appears that we would have to wrap the elevator with a 2hr fire wall with self-closing fire doors to protect the elevator shaft openings. Are there any other protectives required?

 

[RLGA]

1. Technically, no. See Section 706.1.1.
2. Assuming #1 is acceptable, then it might be acceptable only if occupants have direct access to a stairway without egressing through the areas where cars are parked. The preferable solution is to provide an enclosed stairway with direct access from the residential stories.
3. Not a fire wall, but a fire barrier. Regardless, what provision is driving this?

 

[cda]

Welcome!!

 

[Orion's Master]

1. 706.1.1 Party walls was an initial concern but then I thought about the interconnection of casinos in Las Vegas or the ability of elevated walkways in larger cities to connect buildings and assumed that the horizontal exit would be the only means to achieve that ends. I'm not sure how they could connect those entities otherwise. Thoughts on how that would be allowed otherwise? The exception noted is only for anchor buildings and a mall per 402.7.3.1 but that section doesn't exist so my assumption is that the intended reference is 402.4.2.2 and/or 402.4.2.2.1. Which this seems to open up the possibility of connection based on construction type. Other precedent (although a stretch since this is not a mall) is the use of 402.4.2.3 which allows parking garages to be attached to anchor buildings with a 2hr fire barrier separation.
2. Agreed. The direct connection to the stairway would be the safest point of discharge from one building into the other.
3. The section 706 fire wall would be the fire separation wall between the two buildings since the existing parking garage has non-loadbearing CMU walls for the exterior wall facing the lot to be developed. A new fire wall would be needed to separate the two buildings. The new fire wall separating the two structures would need to be structurally stable per 706.2. The separation of the parking garage elevator from the R-2 with the fire wall is because the elevator shaft face is on the property line. So if we were allowed to access and use the elevator from the R-2 side it would need a properly protected opening in the 2hr fire wall (2hr per table 706.4 with exception for reduction from 3hr to 2hr for construction Type V-B of the R-2 occupancy above the 3hr horizontal separation from the Type 1-A construction for the B & M occupancies on the first floor.

I'm trying figure out if this can work since this was how the parking garage was envisioned to work by the city an integral piece of the development of the adjacent lot but I admit it doesn't seem to really work per code except for the generous interpretation needed to use 402.4.2.3.

Ron - Thank you for the response.

 

[cda]

"""about the interconnection of casinos in Las Vegas or the ability of elevated walkways in larger cities to connect buildings and assumed that the horizontal exit would be the only means to achieve that ends. I'm not sure how they could connect those entities otherwise. Thoughts on how that would be allowed otherwise?""""



Two different animals

Las Vegas --- Performance base design

An elevated walk way ---- normally two totally separate buildings and the wall/ door to each one is rated.