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Non-Separated Occupancys- "Most Restrictive"

P

pilgrim

Member
Joined
Sep 14, 2015
Messages
26
Location
california
Hi everyone,

I'm doing a code analysis on a 3 story building. For the time being, I'm looking at qualifying the building under the Non-Separated Occupancy Allowable area (CBC.508.3.2). Under this section I will need to use, "the most restrictive" allowances for occupancy's under consideration for the Type of Construction" to base the Building area and height on...

Problem I'm having is determining "most restrictive." I need to classify the Building as Type VA. However, I also have a A-3 and E on the Ground level. Referring to CBC table 503, the A-3 has a 2 story max with an allowable area of 11,500. However, the "E" has a 1 story max with an Allowable area of 18,500.

So one is more restrictive as pertains to height the other as pertains to floor area. Which occupancy do I use as "most restrictive" to base the building area and height on? Or do I use the most restrictive of both occupancy's?

Thanks for your help as always!
 
You base the height on the most restrictive height, and you base the area on the most restrictive area.
Sounds like one story at 11, 500 s.f. would apply to the ground floor...
But that would be for NEW construction... sounds like you have an EXISTING building which would send you in a different direction altogether...
 
JBI said:
You base the height on the most restrictive height, and you base the area on the most restrictive area.
Sounds like one story at 11, 500 s.f. would apply to the ground floor...
But that would be for NEW construction... sounds like you have an EXISTING building which would send you in a different direction altogether...
Click to expand...
Yes - It is an existing 2 story with a basement, TYPE VA Construction. Suggestions?

Thanks,
 
506.5.2 More than one story above grade plane.
For buildings with more than one story above grade plane and containing mixed occupancies, each story shall individually comply with the applicable requirements of Section 508.1. For buildings with more than three stories above grade plane, the total building area shall be such that the aggregate sum of the ratios of the actual area of each story divided by the allowable area of such stories based on the applicable provisions of Section 508.1 shall not exceed 3.
 
Thanks for the replys. The Building is an existing 3 story. The Ground level has the largest area - I'm Trying to justify it with either the Separated or Non-Separated provisions of the CBC chapt. 508.

My understanding is that either one of two (not including Accessory method) methods to establish allowable floor area and Height have to be used to establish the overall Building Height and allowable floor area(per story): 1. Separated or 2. non-separated(CBC 508).

Is this correct or can a combination of methods be used?

Example: My ground floor has A3/ E/ S2/ B occupancys. Only the S2 needs to be separated and only from the "B" (CBC Table 508.4). The total floor area of the Ground Floor is 13,500 and the S2 only makes up 1,200 (less than 10%). The other Occupancy's do not need to be separated from each other.

1.) If I go with Separated method and determine ratios for each occupancy, my ratio for the Ground Floor is less than 1 which is OK (CBC 508.4.2). No yardage increase is necessary. However, technically only the S2 is separated and only from "B"...

or

2.) Should I employ the most restrictive (non-separated method). If this is the case I will have to base the Floor area on the A3(for floor area), in which case I'm over the allowable floor area and I will need to use the Frontage increase for a 75% Max. (CBC 506). If this is employed what of the S2 which needs separation? (see #3).

or

3.) Or do I use a combination of the above i.e. use the ratio for the S2 but base the entire building allowable area on the "most restrictive" since the majority of the Floor is not separated..

Pretty baffled...I have researched multiple sources and cant find a straight answer.

Thanks for your help!!
 
Ok Pilgrim

Has the building been in use recently ?? If so what occupancy type/ types?

In the very end is this going to be one business ???

If so what is the major use??
 
Howdy Partner..

Has the building been in use recently ?? If so what occupancy type/ types? Existing School Building that is being modernized. It is being used currently. Mainly, A3/E/S2/B

In the very end is this going to be one business ??? No, will remain a School Building with mixed uses.

If so what is the major use?? Multi-purpose Room (A3 Occup.), Administrative/ Transactions (school related) (B), Classroom/ Instruction (E), Storage (S2) and Incidental Uses.


Thanks for the help!
 
The basement does not count as a story.,

IBC 2012
303.1.3 Associated with Group E occupancies.
A room or space used for assembly purposes that is associated with a Group E occupancy is not considered a separate occupancy.

Does CA have something similar
 
Yes, CA has CBC 303.1.3;equivalent.
Thanks for pointing that out.

As far as the basement, yes I am not counting that as a story since its not above the grade plan (Table 503).
 
The use cannot be on a story it is not allowed to be on by table 503....It can be on a story in a building taller than allowed by 503 with uses above that meet 503, but I believe they need to be separated too....If that makes any sense...
 
WHY are we quoting NEW construction Code sections for an EXISTING building???
Start in (Chapter 34 or the Existing Building Code, whichever is applicable) and go from there.
I'm not a left coast guy, so not sure what California has for existing buildings...
 
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I would say because he is "classifying" it to see how far out of compliance it is...you would compare it to new....Or to the code it was constructed, but I have not been given that at this time...No information has been given as to changes...So what section of 34 do you start in?
 
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cda said:
So if the major use is an existing E, and going to stay an E

Isn't the entire building an E


See commentary at 305 and 303.1.3

http://www.cityoflongbeachms.com/NEW WEBSITE/Building Department Page/2012 IBC Code And Commentary Volume I Compressed.pdf
Click to expand...
Thanks everyone for your comments.

Thanks for the Commentary. I'm reading thru it now.

The Building is a 13,500 sq.ft. on each of three levels. Over Half of the total square footage over 3 floors is "E". Also, as pointed out, A occupancy's that are associated with "E" are not considered separate occupancy's. However, we still have "B", S2, Occupancys.

The Building is a mixed Occupancy. The first two levels are mixed with the third level almost entirely an "E".
 
steveray said:
The use cannot be on a story it is not allowed to be on by table 503....It can be on a story in a building taller than allowed by 503 with uses above that meet 503, but I believe they need to be separated too....If that makes any sense...
Click to expand...
Yes, I f I understand correctly I cannot have an "E" occupancy on the third floor above "Grade Plan". However, technically our Ground floor is a basement. Thus our 3rd level is technically a 2nd story. Since I am using sprinklers for an additional story, our "E" should be OK unless I'm missing something....
 
JBI said:
WHY are we quoting NEW construction Code sections for an EXISTING building???
Start in (Chapter 34 or the Existing Building Code, whichever is applicable) and go from there.
I'm not a left coast guy, so not sure what California has for existing buildings...
Click to expand...

This is a tough one to answer. In past projects, when the modernization to an existing School building includes "Alterations" (as defined by CBC 11b-202) the alteration triggers
upgrading to current code. This project includes "alterations" and also includes new "uses" within the existing floor plan layout. Department of State Architect (DSA) here in Cal. also defines what is an alteration and what triggers compliance with current code.

Lastly, we need to re-qualify the building from its old construction type to a VA in order to make the additional alterations, egress etc. work out.

Its a little bit confusing but at times we use existing Building code but if an alteration or a change of use happens, we need to use current code.

Hope that helps a little.
 
steveray said:
I would say because he is "classifying" it to see how far out of compliance it is...you would compare it to new....Or to the code it was constructed, but I have not been given that at this time...No information has been given as to changes...So what section of 34 do you start in?
Click to expand...
Yes - but we are re-classifying it. These are two independent building that are being "joined" at the basement level and re-classified as a single building because we are adding additional egress stairs and doing "alterations". Classifying the two buildings as one help us meet code restrictions for Fire Separation Distance (common property line) etc.
 
Buildings on same lot - 503.1.2

The height of are limitations for both buildings have to meet the allowable height and area limitations for type of construction and occupancy (This section refers to this as section 504 and 506)

Same as non-separated uses in a single building.

Note: Basements does not count as a part of the the allowable area as long as the basement SF does not exceed the SF allowed by a single story building 506.1.3
 
JBI said:
You base the height on the most restrictive height, and you base the area on the most restrictive area.
Sounds like one story at 11, 500 s.f. would apply to the ground floor...
But that would be for NEW construction... sounds like you have an EXISTING building which would send you in a different direction altogether...
Click to expand...

Regarding "most restrictive", curious: where do you find this? The only thing that I find which may be interpreted as this is, CBC 508.3.2, "The allowable building area and height of the building or portion thereof shall be based on the most restrictive allowances for the occupancy groups under consideration for the type of construction of the building in accordance with Section 503.1"

I have looked thru multiple sources and do not seem to find anything that clarifies CBC 508.3.2 that i can point to, in the code or commentary.

Thanks,
 
In my mind the principals office in a school is an "E".

Been there enough times still not "educated"
 
cda said:
In my mind the principals office in a school is an "E".

Been there enough times still not "educated"
Click to expand...

That's my experience as well, so I agree with you on that one!

This 3 story School building has almost an entire level dedicated to "B", " administrative", Nurses, PE office, Workroom etc. but the "B's" are scattered throughout the 3 levels.
 
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