Stairway construction in Type IA/VA Podium building?

[khsmith55]

2018 IBC. 6 story podium building, 1st and 2nd Floors Type IA, 3rd thru 6th Type VA. Building has two stair enclosures rated 2 hours. What type of stair construction can I use? I'm thinking two options. First option would be a steel stair for the 1st and 2nd story (Type IA Building) and a wood stair for the 3rd thru 6th stories (Type VA Building). Second option, which might be a bit "creative", would be rate the stair enclosures 3 hours for the 1st and 2nd story and 2 hour rated for the 3rd thru 6th story and use a wood stair for the full height of the building. My thinking being, if you rate the stair enclosure 3 hours you have essentially "turned" down the horizontal 3 hour separation between the Type IA and VA Buildings.
Any input or solutions is appreciated.

Ken

 

[RLGA]

Section 1011.7 requires stair "materials consistent with the types permitted for the type of construction of the building..." Therefore, wood framing above and steel below would comply with that section.

Your "creative" approach seems reasonable, but not within the code; thus, a code modification request to use an alternative method per Section 104.11 would likely be required. Exception 3 to Section 510.2 establishes a similar precedent for stairway enclosures connecting three stories or less; however, it does not address the construction of the stairs.

 

[CR Design]

IBC 2021 s 510.2, Exception 4 now allows the "creative approach" suggested by @khsmith55.