Fixture Counts Mixed Use Non-Separated

[EasilyConfused]

Have a building that is 1/2 A-3 and 1/2 B Occupancy.

Figuring out the fixture counts for the A-3 part is easy.

I don't understand how to figure out the counts for the B part of the building.

Would storage rooms, conference rooms, break rooms etc which fall under the B occupancy requirements (meaning are not required to be Assembly, S-2 etc because of size or whatever) ALL fall under the B occupancy classification in table 2902.1?

Or, because the building is considered mixed use, would I need to break them out into their S-2, A classifications and calculate the spaces individually.

Assuming that I'm SUPPOSED to keep everything within the B classification, COULD I if counts started to get critical, break them out into individual types (say I wanted to take advantage of smaller fixture counts required for a large storage room (but still B qualified).

Part of my problem with this is that because the building is mixed use, everything is supposed to be classified individually as to occupancy type. But in thinking about it, I can either classify the A-3 and the B parts individually (which seems to make the most sense to me) OR, I can classify all the spaces individually (in this case S-2, E, and individual smaller A-3 spaces).

Can anyone make sense of this?

 

[RLGA]

I try to keep things parallel--in other words, if I have a variety of occupancy groups for purposes of classifying the building per Chapter 3, then I use the exact same occupancy groups when determining plumbing fixture per Chapter 29. This, in my opinion, eliminates a potential comment from a plan reviewer trying to figure out why some occupancy groups are missing in the fixture counts. Although some occupancy groups within a mixed occupancy building may have very low occupant loads, I still break them out individually. Their contribution to the overall fixture count will be minimal since their fractional numbers will not likely make a difference to the total number of fixtures required.

 

[EasilyConfused]

That makes sense (keeping them parallel).

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So, would I be right in this particular hypothetical situation, that I could calculate the occupant loads (and thus the fixture counts to keep parallel) in either one of the two manners below?

- Only do calculations for the A-3 & B occupancies separately then add the results together for total occupant load and calculate total fixture counts similarly using table 1004.1.2.

- Do calculations for the A-3 & B occupancies BUT breakout all of the Storage areas (and classify as S-2), Conference rooms, break rooms, lobbies etc (and classify as A-3), do their individual calculations, and add all together for total occupant load. Similarly (to keep things parallel) do fixture counts for the individual occupancy types, and add those together.

This would mean that my building occupancy type for an identical building could be either:

Mixed Use, Non-Separated- A-3 + B

or

Mixed Use, Non-Separated- A-3 + B + S-2 + Etc.