Split Level Egress

[Mech]

2015 IBC

I have a two story building where the 17,000 sf second story is split. 7,000 sf of floor area is about 4 ft higher than the remaining 10,000 sf.

Must the fire rated stair enclosure reach both levels of the second story or can I use unenclosed stairs between the two? Due to common path of travel limitations, the design will need at least two separate stairs to connect the two levels.

My first thought was two unclosed stairs were OK between the two levels as they are part of the same story.

If unenclosed stairs are permitted, does it matter which level enters the rated stair enclosure? From a floor plan layout, it would be easier for the occupants to descend 4 ft of unenclosed stairs and then access the stair enclosure.

Thanks in advance.

 

[Genduct]

Thought about working a RAMP or 2 into the renovation Plan vs 4x7 28" doesn't sound like it is a big deal

 

[Paul Sweet]

IBC 1009.1 applies if this is a new building:
"Where more than one means of egress is required by Section 1006.2 or 1006.3 from any accessible space, each accessible portion of the space shall be served by not less than two accessible means of egress."

These would be exit access stairs (or ramps). IBC 712.1.12 allows "Vertical openings containing exit access stairways or ramps in accordance with Section 1019".

It would be best to have each level be able to access a stair at that level.