2009 IBC, separated mixed use building, fire ratings?

[khsmith55]

Is my simple mind confused or am I missing something? Given a Type V-B non-sprinklered building, two story with F-1, B and S-2 occupancies. First story is F-1 and second story is B and S-2. Since the F-1 is limited to one story I went to evaluate the building as a separated mixed use building. Table 508.4 requires no separation between the B and F-1 occupancies BUT the S-2 (moderate hazard storage) requires a 2 hour separation from the F-1 and B occupancies. Now my simple minded confusion kicks in, why is there no fire separation required between an S-1 (high hazard storage) and the F-1 and B occupancies but a two hour separation if it’s a S-2? Should I through a case of toilet paper (“paper in rolls”) in the storage room and call it a S-1, ridiculous, but would meet the code.

 

[mtlogcabin]

You are protecting the S-2 from the higher hazard (fire fuel loads) S-1 & B uses.