In cases where things are unclear, I tend to call the building dept in the jurisdiction you are working and ask to speak to a plan checker... they are usually very helpful...

Good Luck.

My knee jerk reaction would be..."yes". But I would go with the above recommendation to ask those who know.

once a person enters a 'protected means of egress' then that protection level must be maintained until they reach the public way. the lobby, if i interpret right is part of the means of egress system in this case. remember there are three parts to the exit system: exit access, exit, and exit discharge.

hope this helps.

Your question is one of those that isn't written well in the IBC.

So the lobby is the exit discharge and the corridor is exit path?

If you have a separate occupancy between the lobby and the corridor and you have an area separation wall between the two I would assume you don't need to rate the lobby. I believe section 1006 might help you out. But then you'll have to check chapter 7 too, since if you have it sprinklered there is a whole other pile of exceptions.

the lobby can't be an exit discharge. see 1023.1: "Exits shall discharge directly to the exterior of the building. The exit discharge shall be at grade or shall provide direct access to grade. The exit discharge shall not reenter a building." the lobby is still part of the 'exit' or 'exit enclosure', the same as the corridor.

these are 'white' pages in my code book meaning they're standard IBC pages and not modified by the State (Oregon). i still believe that the lobby needs to be of the same rating or more than the corridor.

the answer is yes. one hour rating 5/8" type "x" drywall, two layers on ceiling.

Thanks for all your help.
Yes, I found at section 1006, I may not need fire rated corridor with fire sprinkler system, that will solve the whole problem.