The CBC is trying to avoid the so-called "double dipping" concept for occupancies that are regulated by the California State Fire Marshal (SFM).
So, in order for your I2.1 occupancy to be on the second floor (type VA construction), you will need to use the automatic sprinkler system to allow for the additional story (since Table 503 would limit you to a one-story building; I2.1 occupancy and VA construction).
Once you use the sprinkler to allow for a two-story building, then the sprinkler system may not be used for area increase per section 506.3. In other words, your building will need to comply with allowable floor area (section 506) without any sprinkler system increases.
Hope this helps.
"Exception 1 indicates that several types of construction are eliminated from the height increase for fire areas of Group I-2. Each of these types of construction either lacks the fire-resistance rating deemed necessary or includes combustible construction materials in a use where the occupants must rely on the fire sprinkler system for defend-in-place protection."
What exception #1 are you talking about? Exception #1 to section 506.3! That exception in the 2006 IBC deals with Use Group H-1
Here is the language from the 2007 CBC for section 506.3 (see if you find something else there):
506.3 Automatic sprinkler system increase.
Where a building is equipped throughout with an approved automatic sprinkler system in accordance with Section 903.3.1.1, the area limitation in Table 503 is permitted to be increased by an additional 200 percent (Is = 2) for buildings with more than one story above grade plane and an additional 300 percent ( Is = 3) for buildings with no more than one story above grade plane. In other than high-rise buildings, Group A, E, H, I, L and R occupancies or other applications listed in Section 111 regulated by the Office of the State Fire Marshal, these increases are permitted in addition to the height and story increases in accordance with Section 504.2. For Group R-2 buildings of Type VA construction equipped throughout with an approved automatic sprinkler system in accordance with Section 903.3.1.1, these increases are permitted in addition to the height increase in accordance with Section 504.2.
Exception: The area limitation increases shall not be permitted for the following conditions:
1. The automatic sprinkler system increase shall not apply to buildings with an occupancy in Use Group H-1.
2. The automatic sprinkler system increase shall not apply to the floor area of an occupancy in Use Group H-2 or H-
3. For mixed-use buildings containing such occupancies, the allowable area shall be calculated in accordance with Section 508.3.3.2, with the sprinkler increase applicable only to the portions of the building not classified as Use Group H-2 or H-3.
3.Fire-resistance rating substitution in accordance with Table 601, Note e.
4.[SFM] The automatic sprinkler system increase shall not apply to Group L occupancies.[/b]
No Increase in height or Increase in number of stories permitted for Fire areas with an occupancy in Group I-2 of Type IIB, III, IV or V construction.
As Ron noted, the IBC Commentary makes it clear that for certain types of construction (IIB, III, IV and V) the number of stories and height increase noted in section 504.2 can not be used for fire areas with an occupancy in Group "I-2", even with an automatic sprinkler system!
I'm assuming at this point that "I2.1" (a California Building Code (CBC) occupancy designation) is a part of the "I2" occupancy that section 504.2 (exception #1) is talking about.....or is it?
If exception #1 in section 504.2 applied to "I2.1" occupancies (fire areas), you would think that SFM and/or OSHPD would have modified the CBC to include "I2.1" in the exception. I'm not convinced at this point
Have to be careful with this one from now on