• Welcome to The Building Code Forum

    Your premier resource for building code knowledge.

    This forum remains free to the public thanks to the generous support of our Sawhorse Members and Corporate Sponsors. Their contributions help keep this community thriving and accessible.

    Want enhanced access to expert discussions and exclusive features? Learn more about the benefits here.

    Ready to upgrade? Log in and upgrade now.

Can a designer provide a larger occupant load?

H

Henchalwoog

Member
Joined
Nov 6, 2009
Messages
67
Given an unlimited area building of A-3 occupancy utilizing the provision 507.6 of the 2015 IBC due to size (50,000 sq ft gym area - multiple courts), sprinkled and requisite 60'-0" yards and includes accessory areas (mostly B occupancies - offices, dance studios, etc)...given type IIB const the designer has also labeled some of these spaces as "A" occupancies with an increased occupant load factor (dance studios were given a 15 sq ft / occ label in lieu of 50 sq ft per occupant to increase the load to over 50 occupants) - this allowed them to "add" them to the main A-3 occupancy (large gym) so the other accessory occupancies fall under the 10% allowance...is this kosher? They have designed the spaces with the panic devices, etc however it seems to run counter to the intent of the code which would only allow A-3 occupancy...thoughts?
 
I don't understand the question. How the occupant load is calculated for a particular space doesn't (as far as I know) trigger any 10% allowance.

Why isn't a dance studio an 'E' occupancy? What age group is being instructed?
 
Correct - it doesn't...Accessory occupancies have been utilized - they are capped at 10% of the floor area per sec 508.2.3...the designer has applied an increased occupant load (15 sq ft / occupant) to some spaces - dance studios being one of them - to classify them as A-3 and not having them count towards the 10% cap on accessory occupancy areas
 
I would classify them as "B" per section 304.1 under "training and skill development not in a school" - this is a commercial athletic facility that has several courts and will host tournaments, etc
 
Henchalwoog said:
Correct - it doesn't...Accessory occupancies have been utilized - they are capped at 10% of the floor area per sec 508.2.3...the designer has applied an increased occupant load (15 sq ft / occupant) to some spaces - dance studios being one of them - to classify them as A-3 and not having them count towards the 10% cap on accessory occupancy areas
Click to expand...

That's not how occupancy classification works. First you classify the space for use and occupancy classification, THEN you calculate the occupant load.
 
Henchalwoog said:
I would classify them as "B" per section 304.1 under "training and skill development not in a school" - this is a commercial athletic facility that has several courts and will host tournaments, etc
Click to expand...

That certainly sounds like a 'B' occupancy to me. We have permitted commercial dance studios that were independent of schools as Group B.
 
Yes - so I would take your response as an agreement that this is an unethical way of trying to achieve the desired outcome
 
Henchalwoog said:
Yes - so I would take your response as an agreement that this is an unethical way of trying to achieve the desired outcome
Click to expand...
Unethical is a strong word imo... Maybe they just don't fully understand how the code works? My boss, who's been working in architecture for some 30 years, still can't fully wrap his head around how occupant load calculations work - he keeps thinking that "classification" and "function" are the same. It's not unethical, he simply doesn't understand it (no matter how many times I explain it...).

Which is where you people come in to slap them back to reality.
 
I would say it is permissible per Section 1004.5.1. As long as they design the means of egress system to accommodate the increased occupant load, and that "all other requirements of the code are met based on such modified number." Thus, by increasing the occupant load, they must comply with Group A occupancy requirements.

Occupancy group classification sorts various building uses based on relative hazard, such as fire load, occupant load, and familiarity with one's surroundings. Allowing small assembly uses to be classified as part of the main occupancy or another occupancy, or as an accessory occupancy, is a compromise that allows these limited but more hazardous uses without requiring compliance with the added restrictions that would accompany them.

Think about it: is five 500 sq. ft. dance studios (10 occupants) more or less hazardous than one 2,500 sq. ft. dance studio (50 occupants)? In my opinion, they are still equal because
  • the fire load is equivalent (although there is some physical separation that somewhat restricts the spread of fire when five studios are used);
  • the combined occupant load does not change; and,
  • the occupants are equally unfamiliar with their surroundings.
Also, there is no occupant load for dance floors in Table 1004.5. Is the occupant load factor for "Exercise rooms" too much, too little, or just right? (Per the Center for Educator Development in Fine Arts [CEDFA], a dance studio size must be able to accommodate 100 square feet per student. So, probably too little.)

In many cases, designers want to avoid Group A occupancies because of the added requirements that come with that classification, especially area and height limitations. Since the code allows an unlimited area Group A building, what is the objection if a designer wants to use 15 sq. ft. per occupant for a dance studio? They may never see that occupant load, but the building is designed to accommodate it, and the level of hazard is neither increased nor decreased because of it.
 
RLGA:
You make the same points I was questioning myself - hence the post here to see how others would approach it...they have provided the required aspects for the "A" occupancies however since the code for unlimited "A" occupancies is clear that it does not include mixed use then I questioned the use of "overloading" spaces with an occupant load factor that is not associated with the space just to achieve the desired classification to allow for the accessory occupant allowable area (a dance studio teaching the Conga may in fact have 15 sq ft per occupant depending on the length of the line :)
 
I would also wonder if this were taken to an extreme...if the commercial kitchen area was listed at 15 sq ft per occupant and provided with panic devices, etc would that be compliant?
 
Henchalwoog said:
I would also wonder if this were taken to an extreme...if the commercial kitchen area was listed at 15 sq ft per occupant and provided with panic devices, etc would that be compliant?
Click to expand...
A commercial kitchen associated with a Group A-2 dining/drinking area is considered part of the A-2 occupancy group.
 
steveray said:
Don't confuse OL with occupancy group....
Click to expand...
No - the point was that if you have a space with a listed occupant load factor i. e. a kitchen - 200 sq ft per occupant - and they listed it as 15 sq ft per occupant would you accept it with the higher occupant load but the point I was trying to make was that is there a limit to how a designer calculates and thereby classifies a space - office areas @ 7 sq ft per person? etc - or does it matter?
 
Henchalwoog said:
No - the point was that if you have a space with a listed occupant load factor i. e. a kitchen - 200 sq ft per occupant - and they listed it as 15 sq ft per occupant would you accept it with the higher occupant load but the point I was trying to make was that is there a limit to how a designer calculates and thereby classifies a space - office areas @ 7 sq ft per person? etc - or does it matter?
Click to expand...
Function of Space and Occupancy Classification are two completely different things. Just because you throw a 15 net load factor at something doesn't always mean it suddenly becomes an A occupancy. I'll have a conference room in an office classified as B, but the function is unconcentrated and has an OL factor of 15 net.

A kitchen is a kitchen... Not sure how you'd successfully argue "unconcentrated" since the function of a kitchen will basically never change.

Unless they can successfully demonstrate how the space is being used as an assembly space, I wouldn't accept a change in classification.

I WOULD (probably) accept an increased OL by itself with no classification change - no harm there since it just increases life-safety requirements, and more life-safety requirements is rarely a bad thing. Code calls for the "minimum". If they voluntarily increase the load factor (go beyond the minimum), then they just gave themselves more life-safety requirements and more scrutiny, something most designers try to avoid like the plague.

Henchalwoog said:
... this allowed them to "add" them to the main A-3 occupancy (large gym) so the other accessory occupancies fall under the 10% allowance...is this kosher?
Click to expand...
No, not unless they can document and prove why those spaces should be considered A-3. If it's not obvious, ask them for more info. Make them prove what they're claiming. If they try to point to that 50 occupant threshold for changing from B to A, I'd just flat out refuse the increased load factor.
 
Last edited:

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.
 
steveray said:

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.
Click to expand...
Indeed however I assumed this was based on an already establish occupancy i.e. adding to the occupant load of a gym for a graduation ceremony (which I have done previously) and not to change the classification of an occupancy
 
Henchalwoog said:
Yes - so I would take your response as an agreement that this is an unethical way of trying to achieve the desired outcome
Click to expand...

It's only unethical if he knows it's the wrong way to do it and is intentionally using it to get around a code requirement. There's an old saying: 'Never attribute to malice that which can be adequately explained by stupidity." I am more inclined to believe that the architect simply doesn't understand what he/she is doing.
 
Henchalwoog said:
No - the point was that if you have a space with a listed occupant load factor i. e. a kitchen - 200 sq ft per occupant - and they listed it as 15 sq ft per occupant would you accept it with the higher occupant load but the point I was trying to make was that is there a limit to how a designer calculates and thereby classifies a space - office areas @ 7 sq ft per person? etc - or does it matter?
Click to expand...

You are still confusing occupant load calculation with use/occupancy classification.
 
You must log in or register to reply here.
Back
Top