# California - Minimum plumbing fixture calculations



## JPohling (Nov 19, 2018)

I have a multi occupancy tenant improvement where we are trying to calculate the minimum plumbing fixtures that are required.  I have proposed using the ratio method where each occupancy is calculated separately.  This generates a fractional number for the fixtures.  Once each occupancy is calculated and generates its own fractional number all of the occupancies are totaled and then rounded up to the next higher number to establish the combined minimum fixture count.

This is the method that Ron, RLGA has described in his code corner article #33, fall 2010.  This was for IBC

I am having a difficult time with a jurisdiction saying that this ratio method is per Chapter 29 of the CBuildingC which has not been adopted by California as well as this jurisdiction.  It seems to me like the language regarding minimum plumbing fixtures in the 2016 CPlumbingC has the same language where the multiple occupancies are summed and then rounded up.

Am I missing something?  There must be a way to use a ratio rather than just adding up more and more fixtures for each separate occupancy.


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## mark handler (Nov 19, 2018)

2016 CPC
T422.1.... For multiple occupancies, fractional numbers shall be first summed and then rounded to the next whole number.

You round up to the next whole number,  not down to the closest number


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## JPohling (Nov 20, 2018)

mark handler said:


> 2016 CPC
> T422.1.... For multiple occupancies, fractional numbers shall be first summed and then rounded to the next whole number.
> 
> You round up to the next whole number,  not down to the closest number



Mark,  I absolutely agree.  
I am being told that I cannot use the ratio method for a multiple occupancy project because this jurisdiction and California in general has not adopted chapter 29 of the CBC.
Essentially they want me to satisfy each occupancy with whole numbers using no ratios.  As an example I have an A2 with 209 males and 209 females.  For females 209 would require 6 water closets.  6 water closets will satisfy up to 300 females.  I also have B occupancy and S occupancy that will have an additional 16 occupants, 8M and 8F.  instead of being able to use a ratio and satisfy my requirement for the B and S with the 6 total water closets they are requiring that I provide 6 for the A2 and additional toilets for the B and the S sending the total way up.

I do not see anywhere in chapter 4 of the CPC that eliminates the ability to use the ratio method?  On the contrary the language that I have pointed them too and which you highlighted would suggest that the ratio method for multi occupancies is allowed.


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## ADAguy (Nov 20, 2018)

Big city or small city jurisdiction?


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## mark handler (Nov 20, 2018)

JPohling said:


> Mark,  I absolutely agree.
> I am being told that I cannot use the ratio method for a multiple occupancy project because this jurisdiction and California in general has not adopted chapter 29 of the CBC.
> Essentially they want me to satisfy each occupancy with whole numbers using no ratios.  As an example I have an A2 with 209 males and 209 females.  For females 209 would require 6 water closets.  6 water closets will satisfy up to 300 females.  I also have B occupancy and S occupancy that will have an additional 16 occupants, 8M and 8F.  instead of being able to use a ratio and satisfy my requirement for the B and S with the 6 total water closets they are requiring that I provide 6 for the A2 and additional toilets for the B and the S sending the total way up.
> 
> I do not see anywhere in chapter 4 of the CPC that eliminates the ability to use the ratio method?  On the contrary the language that I have pointed them too and which you highlighted would suggest that the ratio method for multi occupancies is allowed.


The quote I provided is from the CPC not the CBC Chapter 29
I know of a lot of cities in CA that do not allow the use of chapter 29 of the CBC.


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## JPohling (Nov 20, 2018)

mark handler said:


> The quote I provided is from the CPC not the CBC Chapter 29


I agree.

ADAguy  this is a large city


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## JPohling (Nov 20, 2018)

Bump!   anyone have any additional insight?


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## mark handler (Nov 21, 2018)

It is the duty of the _building official_ to _interpret_ the code. The only thing you can do is talk to his boss, or do as he says. Nothing anyone here can say will override the AHJ of the project. Bump.


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## RLGA (Nov 21, 2018)

They’re obviously not interpreting the CPC (UPC) correctly. You can challenge their interpretation by taking it to the next level or you can “Ask a Code Question” via the IAPMO website (http://www.iapmo.org/Pages/AskACodeQuestion.aspx) and present the response to the building department.


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## Master Pipe (Dec 5, 2018)

The minimum number of plumbing fixtures ..Calculate the occupant load for the existing building prior to the addition.


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