Small mixed use M/R2 or R3

[Sifu]

Consider a stand-alone new building. The proposal is to provide two R units above an M space below. The M is small enough that it would not require fire sprinklers, but the R units above do. IBC 903.2.8 requires sprinklers throughout the building if the building contains a group R fire area. Is that the end of the story? Sprinklers throughout no matter the particulars? Then, since the R may use a 13R system, does the M follow suit or must it be a 13 system? And if an R3 (transient, think air BB) a 13 D system in the R units? Can you gave two different systems in the same building?

Assuming VB, non-separated but I have no other details at this point, just a vague question I want to be prepared for at a preapp.

 

[Sifu]

I think I found my answer in the commentary.

A common question is whether a mixed-occupancy
building that contains a Group R occupancy could still
use NFPA 13R for the design. If one of the mixed-use
occupancies would require a sprinkler system
throughout the building in accordance with NFPA 13,
then a 13R system would not be allowed. If, however,
the only reason a sprinkler system is being installed
is because there is a Group R fire area within the
building, then an NFPA 13R system would be an
appropriate design choice. The areas that are not
classified as Group R would require protection in
accordance with NFPA 13.

 

[e hilton]

Wow. Common sense wins.

 

[Sifu]

It turns out the R units will be R3 (2 or less) over an M. R3 is permitted to be equipped with a 13D system. 13D isn't really addressed in the particular commentary section I posted and I'm not sure how you could protect the M with a 13D, but if the M isn't required to be sprinklered I'm not sure you can't. You just wouldn't get any of the modifications based on sprinklers. But, the FD is requiring them to use a 13 system in the M, and allowing a 13D in the R3. FD ultimately has the lead on that so que sera.