does separated occupancies trump 2006 IBC 903.2.1.2

[syarn]

if you have a 17000 sf shopping center shell building; 1 story; IIB construction; no sprinkler system; 60' clear on 3 sides and 32' clear on one side...

can you subdivide the tenant spaces into 4 restaurants (A-2 use) each separated by fire rated assemblies in order to NOT put in a fire sprinkler system per section 903.2.1.2 IBC 2006?

if you can do separations what is the rating of each separation as table 508.3.3 says no rating required for A use separations???

is the separation a fire barrier or a fire wall?

is the rating 1 hour per table 602?

 

[hlfireinspector]

Not if the occupant load is over 100 in any one space

 

[High Desert]

No, they may be separate tenant spaces, but they're not separate occupancies. Someones trying to bend the code were it's not supposed to be bent. The heading of 508.3.3 is "separated occupancies" not "separated tenant spaces."

 

[High Desert]

Well after reading the code a little more, I suppose you could if you can divide them into separate fire areas. But having no separation in Table 508.3.3, the only other separation I can think of would be a firewall, which would be 2-hour in accordance with Table 705.4. The other issue would be designing them to allow collapse on one side without damaging the other portion(s) of the structure.

FIRE AREA. The aggregate floor area enclosed and bounded by fire walls, fire barriers, exterior walls or horizontal

assemblies of a building. Areas of the building not provided with surrounding walls shall be included in the fire area if such

areas are included within the horizontal projection of the roof or floor next above.

903.2.1.2 Group A-2. An automatic sprinkler system shall be provided for Group A-2 occupancies where one of the following conditions exists:

1. The fire area exceeds 5,000 square feet (464.5 m2);

2. The fire area has an occupant load of 100 or more; or

3. The fire area is located on a floor other than a level of exit discharge serving such occupancies.

Am I missing something?

 

[Dr. J]

My understanding (limited though it may be as a MEP guy) is that a "Fire Area" exists in the code precisely to allow a designer to chop up a building to avoid sprinklers, and thus the 903.2.1.2 requirement for sprinklers only if a Fire Area exceeds certain limits. Chop up even a large single tenant into enough 5000 sf/100 person or less/first floor Fire Areas, and no sprinklers are required. Per the definition, a Fire Area can be created by either a Fire Barrier or a Fire Wall. Per Table 706.3.9, the required Fire Barrier to create a Fire Area is 2 hours.

It is somewhat similar to the old UBC Area Separation Wall.

 

[north star]

* * * *

syarn,

The separations would be ' fire barriers ', per Section 706 in the 2006 IBC.

Also, Table 706.3.9 would apply. 2 hour rated wall assemblies.



FIRE BARRIERS: "A fire-resistance-rated wall assembly of materials

designed to restrict the spread of fire in which continuity is maintained."

FIRE PARTITIONS: "A vertical assembly of materials designed to

restrict the spread of fire in which openings are protected."

FIRE WALLS: "A fire-resistance-rated wall having protected openings,

which restricts the spread of fire and extends continuously from the

foundation to or through the roof, with sufficient structural stability

under fire conditions to allow collapse of construction on either side

without collapse of the wall."

Also, any components being installed in to the 2 hr. rated wall

assemblies would also have to be 2 hr. rated ( i.e. - junction boxes

and other electrical system components - - see Section 712.3.2 in

the 2006 IBC ).

* * * *

 

[steveray]

Is 506.2 what is allowing it to be 17,000 sf.? A IIB A-2 use according to table 503 is limited to 9500 sf. we didn't get the perimeters to do the math...or am I missing something? You can (maybe) get out of sprinklers...you can not get out of height and area...

 

[Builder Bob]

good catch........ I don't think the allowable area of the A-2 would allow 17,000 SF as a non-seperated strucutrre. If they are using the seperate dprovision, then they(the designer) must provide the calculations so that the sum of the ratios do not exceed 1. I beleive they will be Just outta luck with 17,000 SF. (BTW, with the 32' clear, they do not qualify for an nlimited area building.

 

[High Desert]

That's why I thought the only way it would work would be with firewalls. You would get 4 separate buildings and get the basic allowable of 9,500 sq. ft. per building without having to use any increases for perimeter. Fire barriers would leave it as 1 building and I think it would be over the allowable are even with perimeter increases. The most you could get would be 16,000 and change.

North Star is right on fire barriers. 706.3.9 in the 2006 and 707.3.9 in the 2009.

707.3.9 Fire areas. The fire barriers or horizontal assemblies,

or both, separating a single occupancy into different

fire areas shall have a fire-resistance rating of not less than

that indicated in Table 707.3.9. The fire barriers or horizontal

assemblies, or both, separating fire areas of mixed occupancies

shall have a fire-resistance rating of not less than the

highest value indicated in Table 707.3.9 for the occupancies

under consideration

 

[north star]

* * * *

Help us out ' syarn '........Please provide some more information so

we can, in turn, help you with this design conundrum. :grin:



* * * *

 

[TJacobs]

#1: Can't do an unlimited unsprinklered A-2.

#2: Since tabular area of a IIB A-2 is 9,500 sq. ft., a 2-hour firewall (Table 705.4 footnote a) in the center of the 17,000 will create 2 buildings and 2 fire areas under 9,500 sq. ft. each.

#3: The other two A-2's would need to be separated by 2-hour fire barriers per 706.3.9 into fire areas less than 5,000 sq. ft.

#4: All four A-2's will have to be less than 5,000 sq. ft. each and under 100 occupants each to avoid sprinklers per 903.2.1.2.

 

[TJacobs]

If they sprinkler the entire building they don't need the fire wall or fire barriers because of the sprinkler increase.

 

[Architect1281]

What North Star says

The only way to avoid combined fire areas (mixed Nfpa; Seperated IBC) is to address the issue with SEPERATE BUILDINGS

not seperated uses / occupancies within a single building

then the common walls must be treated as Exterior walls on a property line height and area by individual analysis

 

[JBI]

Any particular reason noone is using the EXISTING building code, or am I missing something?

 

[texasbo]

I agree with those who say that fire barriers may be used to create separate fire areas, which would allow the (4) A occupancies to be nonsprinklered.

However, those who noted that the overall building exceeds the allowable area are also correct.

We do have the perimeters to do the math. W in all cases exceeds 30 feet, so 30 feet is required to be used. That gives a 75% increase, allowing 16,625 sf allowable area, as others have said. At least one firewall is required. Find a storage room at the corner of the building, and build a firewall to eat up 375 sf, and you're ok with fire barriers separating the balance into fire areas no greater than 5000 sf.

 

[syarn]

thx u ACG posters.

northstar & co. pardon the delay; was out yesterday.

yes steveray I missed the height & area limit.

JBI existing building code is certainly an option...hmm...

it was a "scenario" question....which was not thought out well; pardon me.

the real world condition is this:

it is 17000 sf shell; 1 story; IIB; no sprinklers; 60' clear on 3 sides and 32' clear on one side;

the existing tenant subdivision is into 8 spaces; 1 restaurant (A2) 2650sf; 1 liquor store (M) 2400sf & 1 blockbuster (M) 4600sf; 6 business spaces (ups store, ed jones financial, cartridge world, etc);

we are dividing the empty blockbuster space in half and changing the use to restaurant (A2) for our client; just learned that the other half of the blockbuster will also be a five guys restaurant (A2) so the TOTAL square footage in the existing shell building of A2 uses NOW exceeds 5000sf....I was concerned that a fire sprinkler system could NOW be required.

it would seem since each individual A2 space is less than 5000 sf & 100 person occupancy and the new tenant demising wall in the blockbuster would be a 2 hour fire barrier per IBC 2009 section 707.3.9 (eg U411 or U419 walls) that the fire sprinklers are not required....

the OP was taking the logic to the worst case scenario where the landlord changes to ALL restaurant tenants....at first glance it seemed like a "way" (per Dr. J) for a building to be beyond the height & area allowance for an A2 use...

 

[TJacobs]

The Existing Building Code won't help because it may not be adopted in the jurisdiction, and because a change of occupancy class gets you to the same place you are at now. IMHO, if you have the open perimeter increase as texasbo states and the tenant mix is as you updated us with, in my own jurisdiction I'd be focused on meeting Chapter 9 requirements meaning separating each A-2 with 2-hour fire barriers to avoid sprinklers.

 

[JBI]

Pretty sure the EBC ws adopted in PA, but there are many PA members here (including the OP) so we should know for sure any minute now...

I seem to remember at least part of PA was using both EBC AND Chapter 34 of the BC. Haven't checked the newest IBC, but the 2010 NYSEBC now includes all three compliance paths. There are a multitude of options, but the two hour fire barrier should do the trick.