2902.1 FIXTURE COUNT rounding
i'm wondering if anyone has punched the numbers on this to the extent that they can explain it to me. in plumbing fixtures one DIVIDES the Occupant Load by a factor of 2 for each of the sexes. then subsequently proportion fixtures by the (unequal) "Gender Distribution" in the table. this seems pretty straightforward as the result is two numbers (one for male and one for female) and you round up as necessary.
in cases where there is a "5050 Gender Distribution" the code simply provides one value in the chart and you use that value for BOTH the male fixture count and the female fixture count. so if your Occupant Load is 201 and you divide this by two you have 100.5 Occupant Male and 100.5 Occupant Female. and if the (single) value for the fixture count is 1 per 100 you would end up with 2 fixtures Male and 2 fixtures Female. is that right?
what about the Drinking Fountain section which appears to also list a single value?
if you run the numbers as above (same presentation in the chart) you end up with 4 total drinking fountains. if you run them with the "full value" of 201 occupants you would only end up with 3 total drinking fountains.
i'm just sort of curious as the code commentary seems pretty deliberate about dividing the Occupant Load by a factor by TWO /first/ to run Male and Female separately  unless i misread it. and if that is the case the "single value" entries in 2902.1 are handled differently aren't they?
i saw only one other post on this and it was more related to california code and it seems this would be helpful for candidates to be clear about (or at least i'd like to be clear about it...).
THANKS

Jon,
You only use "gender division" for toilets and sinks. Meaning, you take your total occupant load, divide it in half like you've said, and then use those numbers to determine how many male/female toilets and sinks you need.
When it comes to drinking fountains and mop sinks, however, you do not do this. You use the full value. This is because there aren't male and female drinking fountains and mop sinks.
You are correct that you round up as well, like you've done below. Honestly, in real practice, if I truly came up with 201 people in my building, and the fixture counts were based on factors of 100, I would modify my occupant load to be 200 people somehow so that I don't end up with needing 1.005 fixtures and having to round up to 2. Most AHJ's would allow that as well. This being said  for the purposes of the ARE, don't do this. And, I strongly doubt that if asked on the ARE, that you will end up with an occupant load that results in something that small of a differential. It'll be clear as day if you need to round up.

hi david,
thanks a ton.
i partly used the “extreme” case just to emphasize rounding in case anyone is unclear.
but just so i am clear a follow up please? as deliberate as the commentary is with it’s terminology and explanation this issue was slightly confusing.
you are saying that for items (toilets and stalls) you divide the occupant load by two, then calculate each independently  whether the chart has an entry as a “on box” entry (no gender division) or an entry as a two box division (i guess in all cases where there is a two box entry it is split unevenly)?
i mean, i didn’t do the math and the issue of rounding gets slightly confusing but presumably with rounding you end up with different results if you do it one way or anothe way.
does that make sense? i mean if you split the occupant load first, then run the gender numbers independently it seems you rounding up in some cases (for instance where you need to run totals of the ungrounded up numbers as the commentary requires)  that you would end up with additional required fixtures. because they would be split and rounded twice instead of once.
and if you run fountains with the full occupant load value it seems you could just run the full occupant load and /then/ split it later for the “gender divisions” items.
i know this is sort of didactic and seems like splitting hairs but for future testers it seems (?) dissecting the commentary a littl could be helpful.
goodwill,
jon 
Jon,
For toilets and sinks, split the total occupancy first, then do your individual calculations for each gender. Round up those numbers you get.
For water fountains and mop sinks, take your total occupancy and do your calculation. Round up that number.
Really and truly, it can't get any simpler than that.

thanks. sorry for the length. i meant to post this earlier.
basically what we are saying is that for toilets and stalls we divide the occupancy by two and run the numbers for each individual gender where it is specified independently with two separate boxes.
in cases where there is a single entry for these fixture types you don't divide by two and you run the numbers, /then/ divide the result into two genders. and round up then as necessary? the other way to go would be to divide into two /first/ and then run the genders individually on the single entry one at a time.
i can't quite tell for certain but it does seem like on a more complicated case the rounding would result in a higher number if you split it into two first.
i know this is "in the weeds" but i think for some candidates being overly specific about this could help. the chart methodology is a tad confusing imho.

Jon,
My original summary stands, and for the purposes of not confusing other test takers, as you say, I am going to copy and paste it here so that it is abundantly clear:
For toilets and sinks  take your total occupant load, divide it by 2, do the calculation per gender, and round up.
For water fountains and mop sinks  take your total occupant load, do the calculation, and round up.
Period  across the board.
Your question about "why do they split the genders up into two cells in some occupancies and in other occupancies only show one cell?" This is because if you look at the use groups that have two cells, one per gender, there are certain categories within that use group that in fact have a different calculation for men vs. women. The use groups that do not have a different calculation use the one cell method. What IBC has done here is nothing more than an excel spreadsheet formatting thing.
Let's look at A3 for example. It is a twocell format, one cell per gender, but one of the requirements is the same calculation: 1 per 500 people. The other two however are different for men and women. So, rather than using a one cell format for the first one and then shifting to a two cell format for the two with different divisors, they just stuck with the two cell format for all of them. Whatever IBC intern that did this spreadsheet in Excel probably does not know how to combine a one cell and two cell approach.
My assessment above stands.

ok. thanks. i think i used the term “stall” where i should have used sink for lavatory earlier.
ok. i think what i am saying is that if you do the “single cell” entries for water closet or lavatory like you do for a fountain with a single cell value (and not split the gender up first)  say for Business Occuoancy  i think you actually end up with one less fixture than if you split it as if you had two separate values in two cells.
but i get it and sort of hope being s little overdeliberate with the conversation may help other professional candidates. thanks and again apologies for the length.
best,
jon
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