Ummm.... hate to tell you, but you are going to sprinkle at least the residential portion of the building.
[F] 903.2.8 Group R
An automatic sprinkler system installed in accordance with Section 903.3 shall be provided throughout all buildings with a Group R fire area.
[F] 903.2.8.1 Group R-3
An automatic sprinkler system installed in accordance with Section 903.3.1.3 shall be permitted in Group R-3 occupancies.
Given the square footages that you noted, it is only about 2,000sf, so you should be just fine with mixed-use non-separated. But with no separation, the AHJ will most likely (and should per the IBC), have you install a full NFPA 13 system in the entire building.
However, what I would suggest, especially given the size of the building, is that you go for a Live/Work Unit per
IBC Section 419.
419.1 General
A live/work unit shall comply with Sections 419.1 through 419.9.
Exception: Dwelling or sleeping units that include an office that is less than 10 percent of the area of the dwelling unit are permitted to be classified as dwelling units with accessory occupancies in accordance with Section 508.2.
419.1.1 Limitations
The following shall apply to all live/work areas:
- The live/work unit is permitted to be not greater than 3,000 square feet (279 m2) in area;
- The nonresidential area is permitted to be not more than 50 percent of the area of each live/work unit;
- The nonresidential area function shall be limited to the first or main floor only of the live/work unit; and
- Not more than five nonresidential workers or employees are allowed to occupy the nonresidential area at any one time.
You will still end up doing fire sprinklers though...
419.5 Fire Protection
The live/work unit shall be provided with a monitored fire alarm system where required by Section 907.2.9 and an automatic sprinkler system in accordance with Section 903.2.8.