# Plumbing Fixture Calculations



## kveerhusen (Jul 10, 2015)

Hello all! I am hoping someone can shine some light on a situation I have been running across, multiple times.  I’ve tried searching for an answer but can’t seem to find one, or I just don’t like the answer.  But anyway here’s the situation.  I have an existing school (grades 6-8) including classrooms, library, admin., commons/assembly area, stage, and gym with bleachers.  When calculating plumbing fixtures do you have to assume that all these spaces will be occupied at the same time.  It seems ridiculous to think that a fully attended school play and basketball game would be going on all while normal classes are in progress.  Is anyone aware of an area in the code that would take this into account.  For some reason I seem to remember an area in the code that excludes certain areas because that occ. load is counted somewhere else, so that a person is not counted twice.  However I can’t remember or find where that is stated or if I made it up.  If anyone has any thoughts that would be great. Thanks!!


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## cda (Jul 10, 2015)

Welcome

Which building and plumbing code are you under ??

To include edition


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## kveerhusen (Jul 10, 2015)

We are under 2012 IBC and IPC.  I'm not aware of any local modifications


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## mtlogcabin (Jul 10, 2015)

I calculated every space as being occupied at the same time to determine the egress requirements. This will always exceed the actual student numbers the school is designed to hold. Next I encourage/require the assembly areas to have sufficient fixtures for the OL of the assembly areas. A lot of activities in the assembly areas happen after school hours and doors are locked to prevent the public from wandering through the schools. These fixtures will credited for the classroom OL use so you do not have a large number of fixtures but they are available to those that need them during the different hours and functions within the school.

Gyms around here are used at nights and weekends for various functions from craft sales to Rotory basketball games and community dances.

1004.1.2 Areas without fixed seating.

The number of occupants shall be computed at the rate of one occupant per unit of area as prescribed in Table 1004.1.2. For areas without fixed seating, the occupant load shall not be less than that number determined by dividing the floor area under consideration by the occupant load factor assigned to the function of the space as set forth in Table 1004.1.2. Where an intended function is not listed in Table 1004.1.2, the building official shall establish a function based on a listed function that most nearly resembles the intended function.

Exception: Where approved by the building official, the actual number of occupants for whom each occupied space, floor or building is designed, although less than those determined by calculation, shall be permitted to be used in the determination of the design occupant load.


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## kveerhusen (Jul 10, 2015)

Thank you logcabin.  That all makes sense and I would agree.  I think your explanation helps me to formulate an argument should I need to.  I just wish there was a more straight forward answer to these types of situations, so that I would have to try to argue code with a code official.  Thanks!


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## Builder Bob (Jul 10, 2015)

1004.1.2 Areas without fixed seating.

The number of occupants shall be computed at the rate of one occupant per unit of area as prescribed in Table 1004.1.2. For areas without fixed seating, the occupant load shall not be less than that number determined by dividing the floor area under consideration by the occupant load factor assigned to the function of the space as set forth in Table 1004.1.2. Where an intended function is not listed in Table 1004.1.2, the building official shall establish a function based on a listed function that most nearly resembles the intended function.

Exception: Where approved by the building official, the actual number of occupants for whom each occupied space, floor or building is designed, although less than those determined by calculation, shall be permitted to be used in the determination of the design occupant load.


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## steveray (Jul 10, 2015)

We always do full OL....The State gives them a mod for less on fixture counts...


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## zigmark (Jul 10, 2015)

I like Mt.'s logic.  I have stood in line at bathrooms in a gym to use the men's room on more than one occasion.  That said, I have stood in line at a NFL football game just the same at a facility supposedly designed to accommodate the occupant load??  Never enough when ya gotta go I suppose.

ZIG


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## Yikes (Jul 13, 2015)

kveerhusen, mtlogcabin quoted the Building Code, because the plumbing code references the building code for purposes of determining You have 3 options for flexibility:

1) You can use the provision in IBC 1004 that mtlogcabin mentioned above.  I have used this to reduce the occupant load for basketball courts in private fitness centers, so that the code recognized 10 people in a pickup game rather than a high school pep rally.

2) The IPC 403.1.1 additionally allows "approved statistical data" to change the proportions of male-vs-vs female required fixtures.  for example, at a single-sex detention facility, or at a convent, there is no need to assume the occupants are 50% male and 50% female.

3)  Almost all codes have an Administrative section where they will consider alternate means of compliance.  IPC 403.1 allows individual consideration by the building official for "occupancies not listed", and IPC 105.1 also allows the building offical to make modifications as long as the intent of the code is met, and where the letter-of-the-law is not practical.


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## Mr Softy (Jul 14, 2015)

If the only number we are given is the total egress OL, that is what we will use for fixture count calcs.

We will accept modified OL numbers for fixture count purposes only.  But they come from the RDP, and they are detailed and specific to the building and its use areas.

f'rinstance, the area near the gym and auditorium may need fixture amounts that meet the  OL need of those uses, without counting on classroom area fixtures to meet the need.

make sense?


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