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Assembly vs business load limits

bldginsp

bldginsp

Bronze Member
Joined
Oct 22, 2009
Messages
68
Location
Eastern US
2006 IBC states under an assembly use that an occupant load of 50 or less shall be listed as a business use group. Question has arose, do you use 100 sqft per person for maximum floor area as listed under business allowance or do you use the assembly net allowances?
 
Occupancy group and occupant load are independent. Just because you classify it as a B doesn't mean you use an occupant load factor of 100. It would have been perfectly acceptable to post this in commercial building category.
 
Texasbo nailed it. Occupant load has NOTHING to do with occupancy classification! Occupant load is based on the function/use of the space(s).
 
Agree with others. I have a collection agency with 3,000 sq ft "B" occupancy but there are 54 work stations plus a couple of management offices, The occupant load is well over 30 so IBC 2006 Section 1004.2 Increased occupant load would apply.
 
Jumping on the rest, but yes..............OL's based on actual use, then if you fall under the less than 50 OL for other requirements, then the B exception applies
 
texasbo said:
Occupancy group and occupant load are independent. Just because you classify it as a B doesn't mean you use an occupant load factor of 100. It would have been perfectly acceptable to post this in commercial building category.
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I believe you have to use Table 1004.1.1 for determining occupant load and can consider 1004.2 to increase the occupancy. What I'm really asking is which load factor is uses, business or assembly. The reasoning behind ICC to classify 50 or less as a B use group was to avoid RDP requirements for mom and pop restaurants to keep the cost down. The problem comes into occupant load, IPC, IMC, etc., that differs in each use group. Maybe ICC should have also included an exception that indicated how to calculate the max. occupant load for this. Example: RDP designs 45 seats and 5 staff = 50. B occupancy per code. Building is only 1500 sqft. Under Table 1004.1.1 maximum occupancy is 15. Conflict?
 
I would usually agree with most of the posts that occupant load and use group are two different animals here but under the exception in 303.1 the occupant load drives the use classification to be a business classification. "with an occupant load of less than 50 shall be classified as a Group B occupancy." I read that as manditory because it doesn't say may be classified as Group B occupancy.
 
If it's assembly use you use the appropriate assembly use in Table 1004.1.1. If it's 50 or more, it's an A, less than 50 it's a B. I'm not sure what all the confusion is.
 
bldginsp,

If you don't use the proper occupant load classification for all buildings, that would mean that every building less than 5000 sq ft would be a business use, period, because 5000/100 sq ft per occupant is 50 people. While a restaurant with only 750 sq ft seating area would have the same 50 people. If I was understanding your question.
 
bldginsp said:
I would usually agree with most of the posts that occupant load and use group are two different animals here but under the exception in 303.1 the occupant load drives the use classification to be a business classification. "with an occupant load of less than 50 shall be classified as a Group B occupancy." I read that as manditory because it doesn't say may be classified as Group B occupancy.
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Bldinsp - You're reading it correctly. However, just because it requires you to classify it as a B, doesn't mean you use the occupant load factor for office. You use the occupant load factor that matches the use. If the number comes to 50 or more, it's an A, if less than 50, B. Just remember that Table 1004.1.1 has nothing to do with occupancy group. It's merely a tool for arriving at an occupant load.
 
texasbo said:
Bldinsp - You're reading it correctly. However, just because it requires you to classify it as a B, doesn't mean you use the occupant load factor for office. You use the occupant load factor that matches the use. If the number comes to 50 or more, it's an A, if less than 50, B. Just remember that Table 1004.1.1 has nothing to do with occupancy group. It's merely a tool for arriving at an occupant load.
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Texasbo, you hit the nail on the head. I was trying to get you to say that without coaxing you. My BO believe's that you calculate based on my example and I'm with you. The loser in this is the owner who is getting squeezed. I am trying to get them to go before the LBBCOA without losing my job in the end.
 
So the BO is calculating using the correct occupant load factor (15, I assume), but if the number of occupants is less than 50, he's still classifying it as an A?
 
Owww bad bad BO......

2006 IBC

Table 1004.1.1 says

Maximum Floor Area Allowances Per Occupant

Not

Maximum Floor Area Allowances Per Use

The A (Assembly) or B (Business) or H, I, M etc. are group classifications and determine the "use" of an area.

How can you determine occupant load of off a use?
 
Table 1004.1.1 gives you the maximum floor area per occupant.. not the occupant load. Plan reviewers miss this alot; it's not the same as calculating the occupant load.

In any occupancy, the BO can allow 5 sf per person... which is the minimum.. and that's a pretty tight squeeze... OK, go to the social rooms at an ICC conference and see if you actually have 5 sf of personal space.
 
texasbo said:
So the BO is calculating using the correct occupant load factor (15, I assume), but if the number of occupants is less than 50, he's still classifying it as an A?
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No he's calculating at 100 sqft per occupant as stated in under the business use and not the 15 under assembly and no he's classifying it as a B use.
 
Good Lord. Have him read 303.1, exception 1: A building used for assembly purposes with an occupant load of less than 50 persons shall be classified as a group B..."

Have him note that it specifically says used for assembly. That means that you use the assembly floor area from Table 1004.1.
 
I also don't get the confusion here. I think texasbo has stated it clearly.

Would this same individual calculate the occupant load of a conference room in office suite that has a 400 SF conference room as only 4 occupants of the conference room???
 
Probably, we haven't gotten to one of those yet. We just had a discussion of level of fire department access, grade or the end of the 110' ladder truck reach? Guess which one he picked?
 
bldginsp said:
No he's calculating at 100 sqft per occupant as stated in under the business use and not the 15 under assembly and no he's classifying it as a B use.
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Then he's calculating wrong. HOWEVER, for assemly occupancies, you need to use net area, not gross area, so you need to eliminate columns, tables, etc.
 
bldginsp said:
Probably, we haven't gotten to one of those yet. We just had a discussion of level of fire department access, grade or the end of the 110' ladder truck reach? Guess which one he picked?
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You got it, he believes you calculate a high rise at 75' above the end of the ladder reach, so it's not considered a high rise if you have a 110' ladder truck and the building is 150' tall because it doesn't fall in the 75' above the level of fire department access.
 
403.1 Applicability.

The provisions of this section shall apply to buildings with an occupied floor located more than 75 feet (22 860 mm) above the lowest level of fire department vehicle access.

How does the FD get the other trucks up the ladder? :p

How did he become the BO?
 
Being the next in line due to seniority and the plan reviewer has otj training because he was a ag electrician and now reviews plans with no experience in building. Needless to say we have become the laughing stock of our jurisdiction.
 
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