Exterior Access Rooms and Occupancy Calculations

[arwat23]

I'm working on a office TI project in California where we are trying to lower our occupant load. Currently, we have an occupant load of 203 and we want it to get down to at least 200. I've already fudged the numbers in my favor, altered some rooms to lower the count, but I cannot get the occupant load to 200 without making changes our client would rather I not make. There is one thing that may work, but I'm not sure if it actually works with code.

There are a few rooms that are only accessible from the exterior and don't connect to the rest of the interior of the building. Electrical rooms, fire riser rooms, equipment rooms, etc. Nothing accessible to the public. My question is, can I ignore those rooms when calculating the occupant load for plumbing fixtures?

Per CPC/UPC, the occupant load, as determined by CBC/IBC 1004.5, determines the number of plumbing fixtures needed. Is there an exemption for rooms only accessed from the exterior? If I can get below 200, then that reduces the plumbing fixture count by a lot (the jump from 200-201 is intense for B occupancies...). I may be grasping at straws, but I would like to hear other's thoughts on this.

 

[RLGA]

Are you using the occupant load factor of 300sf/occupant for accessory storage areas and mechanical equipment rooms? This can be applied to those spaces you mentioned and also any applicable interior storage areas.

Also, are you using the 150sf/occupant for business areas and not the old 100sf/occupant?

 

[arwat23]

Are you using the occupant load factor of 300sf/occupant for accessory storage areas and mechanical equipment rooms? This can be applied to those spaces you mentioned and also any applicable interior storage areas.

Also, are you using the 150sf/occupant for business areas and not the old 100sf/occupant?

Yep. Got 15 Net for the waiting rooms and break rooms; 150 Gross for offices, corridors, and restrooms; and 300 gross for storage, TI rooms, and electrical rooms.

 

[Yikes]

1. Are you round only AFTER you've added up all the fractional occupancies?
2. Can you make the case for some conference rooms already having their occupants accounted for in general office spaces.
3. If you have a cooperative building official and client, can you limit the total occupant load to 200 (without changing the floor plan) in accordance with CBC 1004.5 exception?

CBC 1004.5 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 1004.5. For areas without fixed seating, the occupant load shall be not 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 1004.5. Where an intended function is not listed in Table 1004.5, 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.​

​

CPC 422.1 Fixture Count​

Plumbing fixtures shall be provided for the type of building occupancy and in the minimum number shown in Table 422.1 [OSHPD 1, 2, 3, 4 & 5] and Table 4-2 and Table 4-3. The total occupant load and occupancy classification shall be determined in accordance with the California Building Code. Occupancy classification not shown in Table 422.1 shall be considered separately by the Authority Having Jurisdiction.

Exception: [BSC, DSA-SS & DSA-SS/CC] Using occupancy classification, described as function of space, determine occupant load factor from Table 4-1 Occupant Load Factor, of this chapter.​

The minimum number of fixtures shall be calculated at 50 percent male and 50 percent female based on the total occupant load. Where information submitted indicates a difference in the distribution of the sexes such information shall be used to determine the number of fixtures for each sex. Once the occupancy load and occupancy are determined, Table 422.1 shall be applied to determine the minimum number of plumbing fixtures required. Where applying the fixture ratios in Table 422.1 results in fractional numbers, such numbers shall be rounded to the next whole number. For multiple occupancies, fractional numbers shall be first summed and then rounded to the next whole number.

 

[arwat23]

1. Are you round only AFTER you've added up all the fractional occupancies?
2. Can you make the case for some conference rooms already having their occupants accounted for in general office spaces.
3. If you have a cooperative building official and client, can you limit the total occupant load to 200 (without changing the floor plan) in accordance with CBC 1004.5 exception?

​

1. That's the problem. Per the plan check comments I received, I'm suppose to round up each room before adding them all up. I originally did each room as a fractional number, then rounded after adding the fractional numbers, but I'm being told that is the incorrect way to do it for Ch10. Funny how this is the first time I've gotten comments like this for occupant load calcs and also happens to be the first time I've done it that way... Now I'm stuck with a plan that might be short 5 water closets.

2. No conference rooms unfortunately. There is a break room though. That would be a good argument, although I've never had much luck with that argument with other jurisdictions.

3. Yeah, I don't think reducing the occupant load by 3 will be that big of an issue. Defiantly won't be for the client. I've been able to do far more with far less on my side. But it's the first time I'm working in this jurisdiction, so trying to to cover all my bases before going to the building official.

 

[steveray]

. That's the problem. Per the plan check comments I received, I'm suppose to round up each room before adding them all up. I originally did each room as a fractional number, then rounded after adding the fractional numbers, but I'm being told that is the incorrect way to do it for Ch10. Funny how this is the first time I've gotten comments like this for occupant load calcs and also happens to be the first time I've done it that way... Now I'm stuck with a plan that might be short 5 water closets.

I do this for egress, but not for fixtures...especially when we are talking about 3 or 4 people...107.2.3 wants OL in all rooms and spaces, and I think that throws some people off....Maybe a formal code change to allow the "rounded down" number for fixtures?

 

[Tim Mailloux]

I do this for egress, but not for fixtures...especially when we are talking about 3 or 4 people...107.2.3 wants OL in all rooms and spaces, and I think that throws some people off....Maybe a formal code change to allow the "rounded down" number for fixtures?

107.2.3 wants OLO in all rooms or spaces, but the OL load for Business is Gross calculation (1 calculation for ALL the B rooms or spaces lumped together). If you have to the OL Gross and then room by room you will end up with different totals due to all the rounding.

 

[steveray]

107.2.3 wants OLO in all rooms or spaces, but the OL load for Business is Gross calculation (1 calculation for ALL the B rooms or spaces lumped together). If you have to the OL Gross and then room by room you will end up with different totals due to all the rounding.

Yep...and as you know...I will use the lower number for fixtures as long as the egress works....

 

[arwat23]

I do this for egress, but not for fixtures...especially when we are talking about 3 or 4 people...107.2.3 wants OL in all rooms and spaces, and I think that throws some people off....Maybe a formal code change to allow the "rounded down" number for fixtures?

CPC says that the occupant load, as determined by building code, is what determines the fixture count. I don't believe I can have two different occupant loads for the building given that wording (the few exceptions to this, namely for DSA-SS and OSHPD projects, don't apply to this project).

422.1 Fixture Count​

Plumbing fixtures shall be provided for the type of building occupancy and in the minimum number shown in Table 422.1 [OSHPD 1, 2, 3, 4 & 5] and Table 4-2 and Table 4-3. The total occupant load and occupancy classification shall be determined in accordance with the California Building Code. Occupancy classification not shown in Table 422.1 shall be considered separately by the Authority Having Jurisdiction.

107.2.3 wants OLO in all rooms or spaces, but the OL load for Business is Gross calculation (1 calculation for ALL the B rooms or spaces lumped together). If you have to the OL Gross and then room by room you will end up with different totals due to all the rounding.

The code comment I received is specifically for egress. The plan reviewer wants each room calculated and rounded up independently (not all one lump sum). I've seen occupant load calcs done both ways, but it seems this jurisdiction has a preference.

 

[Paul Sweet]

Does California have a state review board where you could get an interpretation?

 

[Sifu]

FWIW, based on the information provided, I would do everything available to me as a plans examiner to find my way to yes. I see a few ways I could do that. I would start with the break room. It can be argued that in an assembly space such as a conference room, the occupants are the same as in the B space, though it isn't as clear cut and not my default. However, I do entertain that notion for break rooms, since most organizations don't invite outside users into the break room. Disclaimer: Maybe your plans examiner has done this and still can't find yes, maybe there is more to the story, maybe he is just on a trip.

JMHO

 

[Yikes]

For exit width I believe in rounding up. A room that has 50.1 occupants should have its exit large enough to allow 51 people to pass through its egress door, as a margin of safety.

But a fixture count could and should be added up fractionally per room or space, and only after that would you round up the final number.
There isn’t such a thing as 50.1 bladders.

 

[arwat23]

For exit width I believe in rounding up. A room that has 50.1 occupants should have its exit large enough to allow 51 people to pass through its egress door, as a margin of safety.

I agree. That makes sense. Safety/means of egress wise, I have no complaints with rounding up every room individually.

But a fixture count could and should be added up fractionally per room or space, and only after that would you round up the final number.
There isn’t such a thing as 50.1 bladders.

But isn't the fixture count determined by the occupant load, which is determined by CBC Table 1004.5? Can you have two different occupant loads for the building?

Lets say, rounding up the OL for each room, I get 205 occupants. But not rounding up until the fractional OL of all rooms are added together gets me an occupant load of 180 (there are a LOT of private offices in this project, so rounding up the OL of each room dramatically increased the OL of the building). Would it be typically acceptable to use the 205 for egress/life safety and the 180 for plumbing fixtures? Is there a section of code that addresses this method?

I know CPC Table 4-1 exists, which changes how the OL is calculated for plumbing fixtures, but doesn't that table only apply to state buildings and public schools (BSC, DSA-SS, and DSA-SS/CC projects)?

 

[steveray]

Can you have two different occupant loads for the building?

With a reasonable BO...Yes...

 

[Yikes]

In previous code cycles, the California Plumbing Code had its own occupancy load factor table, separate from the CBC, which could result in different occupant counts. Even the current CPC allows for discretion on the part of the building official when it comes to occupant load counts based on sex, etc. for determining # of fixtures.

 

[arwat23]

With a reasonable BO...Yes...

Huh... Well, I learn something new every day. I had just assumed that after the state fixed the "error" in the CPC that allowed for different occupant load calculations for any project (not sure if it was actually an error, but I've heard from some people that it was) that egress and plumbing OL needed to be the same.

 

[arwat23]

In previous code cycles, the California Plumbing Code had its own occupancy load factor table, separate from the CBC, which could result in different occupant counts. Even the current CPC allows for discretion on the part of the building official when it comes to occupant load counts based on sex, etc. for determining # of fixtures.

Yeah... I kind of wish they didn't change that. That was a very friendly table.