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Max. area increase factor

rktect 1

rktect 1

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Oct 20, 2009
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Illinois
Ok, so the max. area increase for a single floor according to the 2006 IBC for sprinklers, setbacks etc is a factor of 4.75. Is that correct? So, if I had a type 2b building with M occupancy I could get a single floor of 12,500 sq. ft. x 4.75 = 59,375 sq. ft., right? Except that it would be unlimited in area due to single story. This is what I was told at one of my classes I took. Now, 1 year later, if they change their occupancy to an A-2 they would only be allowed 9,500 sq. ft. x 4.75 = 45,125 sq. ft. correct? So if the building was an M use at 46,000 sq. ft. they would not be allowed to change the occupancy to A-2.

Does anybody know what that factor was under the 1996 BOCA? Was it the same 4.75?
 
Re: Max. area increase factor

rktect 1 said:
Ok, so the max. area increase for a single floor according to the 2006 IBC for sprinklers, setbacks etc is a factor of 4.75. Is that correct? So, if I had a type 2b building with M occupancy I could get a single floor of 12,500 sq. ft. x 4.75 = 59,375 sq. ft., right? Except that it would be unlimited in area due to single story. This is what I was told at one of my classes I took. Now, 1 year later, if they change their occupancy to an A-2 they would only be allowed 9,500 sq. ft. x 4.75 = 45,125 sq. ft. correct? So if the building was an M use at 46,000 sq. ft. they would not be allowed to change the occupancy to A-2. Does anybody know what that factor was under the 1996 BOCA? Was it the same 4.75?
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First, it becomes unlimited only if it meets the open area requirements of 507.

Happen to be working on a building of the same vintage and had to get the 93 & 96 BOCA' out of storage this morning. The maximum increase for sprinklers was 200%, but, the open perimeter increase was a maximum of 150% if the building had 30' of open area on all sides. So the maximum was 4.5 or less depending on open perimeter.
 
Re: Max. area increase factor

Yeah. It gets really screwed up cuz it actually went from M to A-3 under 96 BOCA which allowed the A-3 to be unlimited. Now under 2006 an A-3 can not be unlimited area. So they would be in non conformance, but they are not asking for increased area. The want to increase their occupant load. So would there now be a reduction in max. occupant load due to the building being over the max. area already?
 
Re: Max. area increase factor

rktect 1 said:
Yeah. It gets really screwed up cuz it actually went from M to A-3 under 96 BOCA which allowed the A-3 to be unlimited. Now under 2006 an A-3 can not be unlimited area. So they would be in non conformance, but they are not asking for increased area. The want to increase their occupant load. So would there now be a reduction in max. occupant load due to the building being over the max. area already?
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No, not necessarily. See 1004.2.
 
Re: Max. area increase factor

If they qualified for unlimited A-3 under BOCA, and there is no change of use, why can't they stay A-3? As long as all means of egress complies for the occupant load increase I say allow it.
 
Re: Max. area increase factor

TJacobs said:
If they qualified for unlimited A-3 under BOCA, and there is no change of use, why can't they stay A-3? As long as all means of egress complies for the occupant load increase I say allow it.
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Would you allow them more occupants in a space that is already over the max. area by 12,000 sq. ft. by the new code 2006 IBC vs. 1996 BOCA? That 12,000 sq. ft. is 12,000 sq. ft. more occupants which would come to about 284 occupants over what should be their max. area even though the provided means of egress is adequate for the total load.
 
Re: Max. area increase factor

This reminds me of phone conversations in the building department....

What exactly are the Owner's proposing to do?
 
Re: Max. area increase factor

I'm not quite sure how you arrived at a 4.75 increase figure.

Use Group M / II-B type of construction = 12,500. Maximum .75 frontage increase. MAximum 300% increase in a one-stroy building for sprinklers. 300% + 75% = 375% increase for an overall allowable floor area of 4.75.
 
Re: Max. area increase factor

Big Mac said:
Use Group M / II-B type of construction = 12,500. Maximum .75 frontage increase. MAximum 300% increase in a one-stroy building for sprinklers. 300% + 75% = 375% increase for an overall allowable floor area of 4.75.
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Those increases are added to the tabular value, so 4.75 is a shortcut:

At + As + Af = Aa , is the same as

1.0(At)+3.0(At)+0.75(At) = 4.75(At)
 
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