Can a designer provide a larger occupant load?

[Yankee Chronicler]

1004.5.1​

The occupant load permitted in any building, or portion thereof, is permitted to be increased from that number established for the occupancies in Table 1004.5, provided that all other requirements of the code are met based on such modified number and the occupant load does not exceed one occupant per 7 square feet (0.65 m2) of occupiable floor space. Where required by the building official, an approved aisle, seating or fixed equipment diagram substantiating any increase in occupant load shall be submitted. Where required by the building official, such diagram shall be posted.

Correct.

And NONE of that changes the use group or occupancy classification of the space or spaces in question.

 

[Henchalwoog]

You are still confusing occupant load calculation with use/occupancy classification.

I think my example was not the best...I understand the occupant load factors - in this instance they are applying a more concentrated occupant load factor to achieve a higher number of occupants to classify it as an "A" occupancy. Keep in mind that in my particular instance the designer is trying to provide accessory occupancies to a main occupancies and using the higher occupant load to add them to the main occupancy so that they do not exceed the 10% cap thus allowing them to have more accessory spaces than with the main occupancy alone...I would not have an issue if they have a 800 sq ft conference room and listed it at 7 sq ft per occupant - that is assembly to assembly...I would question if there was a 2000 sq ft fitness room and they listed it as 15 sq ft per occupant to achieve an assembly occupancy.

 

[Yankee Chronicler]

I think my example was not the best...I understand the occupant load factors - in this instance they are applying a more concentrated occupant load factor to achieve a higher number of occupants to classify it as an "A" occupancy. Keep in mind that in my particular instance the designer is trying to provide accessory occupancies to a main occupancies and using the higher occupant load to add them to the main occupancy so that they do not exceed the 10% cap thus allowing them to have more accessory spaces than with the main occupancy alone..

I understand that's what the designer is trying to do. And that's not how it works. The occupancy classification is determined based on how the space is used, NOT by how many people are in it. A conference room in an office suite is classified as a Business use, but the occupant load is calculated at 1:15 (or maybe 1:7) without changing the conference room to an Assembly occupancy. Same for the waiting room in a doctor's office.

I would not have an issue if they have a 800 sq ft conference room and listed it at 7 sq ft per occupant - that is assembly to assembly...I would question if there was a 2000 sq ft fitness room and they listed it as 15 sq ft per occupant to achieve an assembly occupancy.

But a fitness center IS an Assembly use: It's an A-3.

A better example might be something like a hotel ballroom, which may be rented out and configured for a number of different types of layout, from a trade show to a high school reunion to a lecture series (or the annual ICC code hearings). Depending on how it's being used, it could be classified as an A-2 (Banquet hall) or it could be classified as an A-3 (Lecture hall). I would expect to see it classified as both (mixed use, non-separated), and the number and capacity of exits calculated based on the largest anticipated occupant load. But ... what is that? As a banquet hall, it would be based on tables and chairs, so one person per 15 square feet. As a lecture hall, it could be just rows of chairs so it would use a factor of one person per 7 square feet.

But maybe the hotel anticipates hosting receptions where people just stand and mill around. Standing assembly is one person per 5 square feet. So maybe the venue uses that, comes up with a number, and the manager says "Our other properties see more than that when they host receptions." Back when I started as an architect, the occupant load factor for standing assembly was one person per 3 square feet, so maybe they choose to use that and they arrive at a significantly higher occupant load. As long as they provide sufficient numbers, capacity, and distribution of means of egress, they can do that under IBC 1004.5.1.

That has NOTHING to do with the use and occupancy classification. It is what it is, and invoking 1004.5.1 to seek approval for a larger occupant load does NOT change the use and occupancy classification.

 

[Joe.B]

 

[Yankee Chronicler]

There's a reason why use and occupancy classification are found in Chapter 3, but we don't get to calculating occupant load until Chapter 10.



Table 1004.5 bases the occupant load calculation on the "Function of [the] Space," not on the use and occupancy classification of the building or portion of the building. What the designer is trying to do can't be done. Whether they understand that and are being unethical, or they're just stupid -- I have no idea. Back to my post about never attributing to malice that which can be adequately explained by stupidity.

 

[Henchalwoog]

I understand that's what the designer is trying to do. And that's not how it works. The occupancy classification is determined based on how the space is used, NOT by how many people are in it. A conference room in an office suite is classified as a Business use, but the occupant load is calculated at 1:15 (or maybe 1:7) without changing the conference room to an Assembly occupancy. Same for the waiting room in a doctor's office.



But a fitness center IS an Assembly use: It's an A-3.

A better example might be something like a hotel ballroom, which may be rented out and configured for a number of different types of layout, from a trade show to a high school reunion to a lecture series (or the annual ICC code hearings). Depending on how it's being used, it could be classified as an A-2 (Banquet hall) or it could be classified as an A-3 (Lecture hall). I would expect to see it classified as both (mixed use, non-separated), and the number and capacity of exits calculated based on the largest anticipated occupant load. But ... what is that? As a banquet hall, it would be based on tables and chairs, so one person per 15 square feet. As a lecture hall, it could be just rows of chairs so it would use a factor of one person per 7 square feet.

But maybe the hotel anticipates hosting receptions where people just stand and mill around. Standing assembly is one person per 5 square feet. So maybe the venue uses that, comes up with a number, and the manager says "Our other properties see more than that when they host receptions." Back when I started as an architect, the occupant load factor for standing assembly was one person per 3 square feet, so maybe they choose to use that and they arrive at a significantly higher occupant load. As long as they provide sufficient numbers, capacity, and distribution of means of egress, they can do that under IBC 1004.5.1.

That has NOTHING to do with the use and occupancy classification. It is what it is, and invoking 1004.5.1 to seek approval for a larger occupant load does NOT change the use and occupancy classification.

Well it COULD be certainly - but 2000 sq ft divided by 50 sq ft per person (exercise) would be less than 50 so I would classify it as "B"

 

[arwat23]

in this instance they are applying a more concentrated occupant load factor to achieve a higher number of occupants to classify it as an "A" occupancy.

That's not how that works. Like Yankee Chronicler said, OL means very little to the Classification.

You could flip it. An assembly space that's small or under 50 occupants doesn't have to be classified as A - it could be B or whatever it's accessory too. But I don't believe there's a mechanism for forcing an assembly classification on non-assembly spaces.

The designer either need to prove to you that their classifications make sense (not based on OL), or they need to find a section of code that supports an increased OL can force an assembly classification.

Edit: Is there a possibility that they genuinely believe those areas are classified as assembly and just blanket apply an assembly load factor? I had someone at a firm I worked at do that a few times.

 

[Joe.B]

2000 sq ft divided by 50 sq ft per person (exercise) would be less than 50 so I would classify it as "B"

An assembly space that's small or under 50 occupants

... can (shall?) be reclassified as a B.

303.1.1 Small buildings and tenant spaces. A building or
tenant space used for assembly purposes with an occupant
load of less than 50 persons shall be classified as a Group
B occupancy.

This is why I shared that "cart before the horse" meme. The information isn't wrong, it's the approach. Start with the appropriate classification per Chapter 3, then work from there. It's all about risk. The intended purpose is Assembly (higher risk) but the low occupant load allows the reclassification to a lower risk use.

SECTION 301
SCOPE
301.1 General. The provisions of this chapter shall control
the classification of all buildings and structures as to occupancy
and use. Different classifications of occupancy and use
represent varying levels of hazard and risk to building occupants
and adjacent properties.
SECTION 302
OCCUPANCY CLASSIFICATION
AND USE DESIGNATION
302.1 Occupancy classification. Occupancy classification is
the formal designation of the primary purpose of the building,
structure or portion thereof. Structures shall be classified into
one or more of the occupancy groups specified in this section
based on the nature of the hazards and risks to building occupants
generally associated with the intended purpose of the
building or structure. An area, room or space that is intended to
be occupied at different times for different purposes shall
comply with all applicable requirements associated with such
potential multipurpose. Structures containing multiple occupancy
groups shall comply with Section 508. Where a structure
is proposed for a purpose that is not specified in 'this section,
such structure shall be classified in the occupancy it most
nearly resembles based on the fire safety and relative hazard.
Occupied roofs shall be classified in the group that the occupancy
most nearly resembles, according to the fire safety and
relative hazard, and shall comply with Section 503.1.4.

 

[Yankee Chronicler]

Well it COULD be certainly - but 2000 sq ft divided by 50 sq ft per person (exercise) would be less than 50 so I would classify it as "B"

That's going in the opposite direction from the situation in the opening post. As Joe B. noted, there's a specific provision covering this.

 

[Henchalwoog]

That's going in the opposite direction from the situation in the opening post. As Joe B. noted, there's a specific provision covering this.

Yes - I was trying to illustrate what the designer was trying to do - just because they list the exercise room at 15 sq ft per person does not make it an "A" occupancy or does it? That is what I was offering to the group - to see if they would allow it...if this was only a singular instance and they designed the egress, etc for an "A" occupancy I would likely have no issue but the designer is using it to allow an unlimited area "A" occupancy with accessory occupancies so it seems to be a bigger issue.

 

[Yankee Chronicler]

Yes - I was trying to illustrate what the designer was trying to do - just because they list the exercise room at 15 sq ft per person does not make it an "A" occupancy or does it? That is what I was offering to the group - to see if they would allow it...

I would not. The code does not.

if this was only a singular instance and they designed the egress, etc for an "A" occupancy I would likely have no issue but the designer is using it to allow an unlimited area "A" occupancy with accessory occupancies so it seems to be a bigger issue.

You still seem to be missing the point. With an increased occupant load, they would not be designing for "an 'A' occupancy," they would be designing for a 'B' occupancy with an increased occupant load. We get what the designer wants to do, and he/she cannot do that. As multiple responses have attempted to explain, that's not how the code works.

 

[Paul Sweet]

If they try to increase the occupant load too much it might bite them in additional plumbing fixtures being required.

 

[arwat23]

... just because they list the exercise room at 15 sq ft per person does not make it an "A" occupancy or does it?

Listing the exercise room at 15 sq.ft. per person does not make it an A occupancy. There's nothing in code that I know of that would suggest that.

 

[Henchalwoog]

If they try to increase the occupant load too much it might bite them in additional plumbing fixtures being required.

Yes - checked into that and they were good - I sent the designer an email indicating that the logic used did not pass muster and they want a teams meeting so we will see what transpires.

 

[Yankee Chronicler]

Yes - checked into that and they were good - I sent the designer an email indicating that the logic used did not pass muster and they want a teams meeting so we will see what transpires.

Can we sit in?

Ask the designer to explain his/her code path. It should be ... enlightening.

 

[Henchalwoog]

Can we sit in?

Ask the designer to explain his/her code path. It should be ... enlightening.

Well as an architect in a previous life I also know what it feels like to be on the other end of the gun

 

[Yankee Chronicler]

Well as an architect in a previous life I also know what it feels like to be on the other end of the gun

I'm still licensed as an architect as well as a building official. I know what it's like -- and it was often extremely frustrating. Like the time both a building official and a fire marshal told me there was no such thing as a horizontal exit. At times like that, you can't do anything other than STFU and submit a formal appeal.

 

[Henchalwoog]

Oh my...it goes without saying that you provided them with the code sections, etc...and they still did not allow it?

 

[Yankee Chronicler]

Oh my...it goes without saying that you provided them with the code sections, etc...and they still did not allow it?

Quote (from one of them, with the other nodding sagely in agreement): "Never heard of it. There's no such thing."

 

[Tim Mailloux]

Playing devils advocate here, maybe the primary day-to-day use of the space is an exercise room. However, given that it's a large open space, the owner intends to occasionally use it for other functions that are assembly in nature and those functions would require an occupant load factor of 1 per 15 square feet.

 

[Henchalwoog]

Playing devils advocate here, maybe the primary day-to-day use of the space is an exercise room. However, given that it's a large open space, the owner intends to occasionally use it for other functions that are assembly in nature and those functions would require an occupant load factor of 1 per 15 square feet.

That is a valid point however if that is the case couldn't you make the case for an open office space? It is a B occupancy Monday through Friday but then on the weekends it is a party room? I can see the situation where one assembly occupancy for a more dense occupancy (gym used for a graduation ceremony) but can you take a space and classify it (and this is a very specific instance) only to achieve a specific end which is to allow the additional area under the accessory occupancy provisions? Do you classify a space on the majority of the use or the one off?

 

[Yankee Chronicler]

Playing devils advocate here, maybe the primary day-to-day use of the space is an exercise room. However, given that it's a large open space, the owner intends to occasionally use it for other functions that are assembly in nature and those functions would require an occupant load factor of 1 per 15 square feet.

If that's the case, it's the owner's (and thereby the designer's) responsibility to properly declare the assembly use in the construction documents.

Superficially that may appear to be what's happening here, but it's not really the case. Here, the designer is declaring that some space will be occupied as an dance studios, and then he/she is arbitrarily assigning unrealistically high occupant load factors not because the spaces will ever be used as assembly spaces with tables and chairs, but solely so that on paper it looks like there's more A-3 space than there is, and thus other spaces can be classified as accessory to the A-3 rather than treated as whatever they actually are under mixed use and occupancy provisions of the code.

 

[RLGA]

What is the "function of space" for a dance studio? Is it an assembly? Business? Educational? Exercise? There is no objective answer—it is in the eye (or bias) of the beholder. If they are teaching dance in those rooms, they could be classified as classrooms (20 sq. ft. per occupant), and classrooms with more than 49 occupants are classified as Group A-3 occupancies, even though an "assembly" occupant load factor was not used. If 20 sq. ft. per occupant helps the OP's architect reach 50 occupants for those rooms, I would suggest the architect label them as "Dance Classrooms" if that would satisfy the BO.

The classification of an assembly occupancy is based on the description in Section 303.1 and on a 50-occupant threshold, regardless of how the occupant load is determined (the section does not state "in accordance with Section 1004.5").

Section 303.1.2 states that a small assembly space shall not be classified as an Assembly occupancy if the occupant load is less than 50 or the space is less than 750 sq. ft. (which ironically is 50 occupants at 15 sq. ft. per occupant). I assume the small dance studios have a floor area of at least 750 sq. ft.; otherwise, the architect couldn't use the unconcentrated assembly load factor to reach 50 occupants. Thus, that means subparagraph #2 of Section 303.1.2 does not apply.

However, subparagraph #1 sets the 50-occupant threshold that everyone is familiar with. Again, that subparagraph does not stipulate how the occupant load is determined. That leaves Section 1004 as the sole means to determine occupant load, and Section 1004.5.1 permits the occupant load to be increased under certain conditions (approval by the BO is not one of them). When the occupant load is increased per Section 1004.5.1, it must comply with all other code requirements "based on such modified number." Thus, a room used for an assembly purpose (I think we all agree that a dance studio is an assembly purpose) with an occupant load of 50 or more (regardless of the method used to determine the occupant load per the code) must be classified as an Assembly occupancy per Sections 1004.5.1 and 303.1.

The intent of Section 303.1.2 is to alleviate the restrictive requirements of an Assembly occupancy on an entire building when only minor assembly spaces exist. However, regarding the project the OP presented, we have a building intentionally designed for large-scale assembly purposes, and you want to squabble over some minor assembly spaces because of their size? Is the architect using the code to their advantage? Of course, they are—there is nothing in the IBC that prevents them from using that pathway. This is just like the BO who made me put in firestopping for a penetration in a 1-hour, cast-in-place floor assembly when there was an approximate 500 sq. ft. vertical opening (complying with Section 712) just a few feet away within the same enclosed space. Why? The BO knew it was illogical, but demanded it because the code specifically required it (i.e., he used the code to his advantage).

 

[Henchalwoog]

So interestingly enough one point made by the designer is that when a use such as a bar is calculated at 15 sq ft per person and it is under 50 occupants it is considered a "B" occupancy but if over 50 it is an "A" occupancy and the use has not changed - they asked why it would not be the same with a weight room or dance studio...I indicated it was something to consider however I did say that in that example the occupant load factor did not change - it was 15 sq ft and only the size of the space resulted in an occupant load and was not a change from 50 sq ft per occupant (exercise) to 15 sq ft per occupant as they are indicating

What is the "function of space" for a dance studio? Is it an assembly? Business? Educational? Exercise? There is no objective answer—it is in the eye (or bias) of the beholder. If they are teaching dance in those rooms, they could be classified as classrooms (20 sq. ft. per occupant), and classrooms with more than 49 occupants are classified as Group A-3 occupancies, even though an "assembly" occupant load factor was not used. If 20 sq. ft. per occupant helps the OP's architect reach 50 occupants for those rooms, I would suggest the architect label them as "Dance Classrooms" if that would satisfy the BO.

The classification of an assembly occupancy is based on the description in Section 303.1 and on a 50-occupant threshold, regardless of how the occupant load is determined (the section does not state "in accordance with Section 1004.5").

Section 303.1.2 states that a small assembly space shall not be classified as an Assembly occupancy if the occupant load is less than 50 or the space is less than 750 sq. ft. (which ironically is 50 occupants at 15 sq. ft. per occupant). I assume the small dance studios have a floor area of at least 750 sq. ft.; otherwise, the architect couldn't use the unconcentrated assembly load factor to reach 50 occupants. Thus, that means subparagraph #2 of Section 303.1.2 does not apply.

However, subparagraph #1 sets the 50-occupant threshold that everyone is familiar with. Again, that subparagraph does not stipulate how the occupant load is determined. That leaves Section 1004 as the sole means to determine occupant load, and Section 1004.5.1 permits the occupant load to be increased under certain conditions (approval by the BO is not one of them). When the occupant load is increased per Section 1004.5.1, it must comply with all other code requirements "based on such modified number." Thus, a room used for an assembly purpose (I think we all agree that a dance studio is an assembly purpose) with an occupant load of 50 or more (regardless of the method used to determine the occupant load per the code) must be classified as an Assembly occupancy per Sections 1004.5.1 and 303.1.

The intent of Section 303.1.2 is to alleviate the restrictive requirements of an Assembly occupancy on an entire building when only minor assembly spaces exist. However, regarding the project the OP presented, we have a building intentionally designed for large-scale assembly purposes, and you want to squabble over some minor assembly spaces because of their size? Is the architect using the code to their advantage? Of course, they are—there is nothing in the IBC that prevents them from using that pathway. This is just like the BO who made me put in firestopping for a penetration in a 1-hour, cast-in-place floor assembly when there was an approximate 500 sq. ft. vertical opening (complying with Section 712) just a few feet away within the same enclosed space. Why? The BO knew it was illogical, but demanded it because the code specifically required it (i.e., he used the code to his advantage).

Interesting that you labeled the use as assembly as a general rule - would it (could it) not be exercise? To me a dance "studio" is where practice takes place and the dancers are spread out to allow them to turn, jump, etc...I agree that the designer can select the occupant load factor to a point - I would certainly question a kitchen at 15 sq ft per person but if pressed to show where there is a violation I do not think I can show anything in print save that it is not the intent of the code